path: root/libavformat/avformat.h (plain)
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1	/*
2	* copyright (c) 2001 Fabrice Bellard
3	*
4	* This file is part of FFmpeg.
5	*
6	* FFmpeg is free software; you can redistribute it and/or
7	* modify it under the terms of the GNU Lesser General Public
8	* License as published by the Free Software Foundation; either
9	* version 2.1 of the License, or (at your option) any later version.
10	*
11	* FFmpeg is distributed in the hope that it will be useful,
12	* but WITHOUT ANY WARRANTY; without even the implied warranty of
13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14	* Lesser General Public License for more details.
15	*
16	* You should have received a copy of the GNU Lesser General Public
17	* License along with FFmpeg; if not, write to the Free Software
18	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19	*/
20
21	#ifndef AVFORMAT_AVFORMAT_H
22	#define AVFORMAT_AVFORMAT_H
23
24	/**
25	* @file
26	* @ingroup libavf
27	* Main libavformat public API header
28	*/
29
30	/**
31	* @defgroup libavf libavformat
32	* I/O and Muxing/Demuxing Library
33	*
34	* Libavformat (lavf) is a library for dealing with various media container
35	* formats. Its main two purposes are demuxing - i.e. splitting a media file
36	* into component streams, and the reverse process of muxing - writing supplied
37	* data in a specified container format. It also has an @ref lavf_io
38	* "I/O module" which supports a number of protocols for accessing the data (e.g.
39	* file, tcp, http and others). Before using lavf, you need to call
40	* av_register_all() to register all compiled muxers, demuxers and protocols.
41	* Unless you are absolutely sure you won't use libavformat's network
42	* capabilities, you should also call avformat_network_init().
43	*
44	* A supported input format is described by an AVInputFormat struct, conversely
45	* an output format is described by AVOutputFormat. You can iterate over all
46	* registered input/output formats using the av_iformat_next() /
47	* av_oformat_next() functions. The protocols layer is not part of the public
48	* API, so you can only get the names of supported protocols with the
49	* avio_enum_protocols() function.
50	*
51	* Main lavf structure used for both muxing and demuxing is AVFormatContext,
52	* which exports all information about the file being read or written. As with
53	* most Libavformat structures, its size is not part of public ABI, so it cannot be
54	* allocated on stack or directly with av_malloc(). To create an
55	* AVFormatContext, use avformat_alloc_context() (some functions, like
56	* avformat_open_input() might do that for you).
57	*
58	* Most importantly an AVFormatContext contains:
59	* @li the @ref AVFormatContext.iformat "input" or @ref AVFormatContext.oformat
60	* "output" format. It is either autodetected or set by user for input;
61	* always set by user for output.
62	* @li an @ref AVFormatContext.streams "array" of AVStreams, which describe all
63	* elementary streams stored in the file. AVStreams are typically referred to
64	* using their index in this array.
65	* @li an @ref AVFormatContext.pb "I/O context". It is either opened by lavf or
66	* set by user for input, always set by user for output (unless you are dealing
67	* with an AVFMT_NOFILE format).
68	*
69	* @section lavf_options Passing options to (de)muxers
70	* It is possible to configure lavf muxers and demuxers using the @ref avoptions
71	* mechanism. Generic (format-independent) libavformat options are provided by
72	* AVFormatContext, they can be examined from a user program by calling
73	* av_opt_next() / av_opt_find() on an allocated AVFormatContext (or its AVClass
74	* from avformat_get_class()). Private (format-specific) options are provided by
75	* AVFormatContext.priv_data if and only if AVInputFormat.priv_class /
76	* AVOutputFormat.priv_class of the corresponding format struct is non-NULL.
77	* Further options may be provided by the @ref AVFormatContext.pb "I/O context",
78	* if its AVClass is non-NULL, and the protocols layer. See the discussion on
79	* nesting in @ref avoptions documentation to learn how to access those.
80	*
81	* @section urls
82	* URL strings in libavformat are made of a scheme/protocol, a ':', and a
83	* scheme specific string. URLs without a scheme and ':' used for local files
84	* are supported but deprecated. "file:" should be used for local files.
85	*
86	* It is important that the scheme string is not taken from untrusted
87	* sources without checks.
88	*
89	* Note that some schemes/protocols are quite powerful, allowing access to
90	* both local and remote files, parts of them, concatenations of them, local
91	* audio and video devices and so on.
92	*
93	* @{
94	*
95	* @defgroup lavf_decoding Demuxing
96	* @{
97	* Demuxers read a media file and split it into chunks of data (@em packets). A
98	* @ref AVPacket "packet" contains one or more encoded frames which belongs to a
99	* single elementary stream. In the lavf API this process is represented by the
100	* avformat_open_input() function for opening a file, av_read_frame() for
101	* reading a single packet and finally avformat_close_input(), which does the
102	* cleanup.
103	*
104	* @section lavf_decoding_open Opening a media file
105	* The minimum information required to open a file is its URL, which
106	* is passed to avformat_open_input(), as in the following code:
107	* @code
108	* const char *url = "file:in.mp3";
109	* AVFormatContext *s = NULL;
110	* int ret = avformat_open_input(&s, url, NULL, NULL);
111	* if (ret < 0)
112	* abort();
113	* @endcode
114	* The above code attempts to allocate an AVFormatContext, open the
115	* specified file (autodetecting the format) and read the header, exporting the
116	* information stored there into s. Some formats do not have a header or do not
117	* store enough information there, so it is recommended that you call the
118	* avformat_find_stream_info() function which tries to read and decode a few
119	* frames to find missing information.
120	*
121	* In some cases you might want to preallocate an AVFormatContext yourself with
122	* avformat_alloc_context() and do some tweaking on it before passing it to
123	* avformat_open_input(). One such case is when you want to use custom functions
124	* for reading input data instead of lavf internal I/O layer.
125	* To do that, create your own AVIOContext with avio_alloc_context(), passing
126	* your reading callbacks to it. Then set the @em pb field of your
127	* AVFormatContext to newly created AVIOContext.
128	*
129	* Since the format of the opened file is in general not known until after
130	* avformat_open_input() has returned, it is not possible to set demuxer private
131	* options on a preallocated context. Instead, the options should be passed to
132	* avformat_open_input() wrapped in an AVDictionary:
133	* @code
134	* AVDictionary *options = NULL;
135	* av_dict_set(&options, "video_size", "640x480", 0);
136	* av_dict_set(&options, "pixel_format", "rgb24", 0);
137	*
138	* if (avformat_open_input(&s, url, NULL, &options) < 0)
139	* abort();
140	* av_dict_free(&options);
141	* @endcode
142	* This code passes the private options 'video_size' and 'pixel_format' to the
143	* demuxer. They would be necessary for e.g. the rawvideo demuxer, since it
144	* cannot know how to interpret raw video data otherwise. If the format turns
145	* out to be something different than raw video, those options will not be
146	* recognized by the demuxer and therefore will not be applied. Such unrecognized
147	* options are then returned in the options dictionary (recognized options are
148	* consumed). The calling program can handle such unrecognized options as it
149	* wishes, e.g.
150	* @code
151	* AVDictionaryEntry *e;
152	* if (e = av_dict_get(options, "", NULL, AV_DICT_IGNORE_SUFFIX)) {
153	* fprintf(stderr, "Option %s not recognized by the demuxer.\n", e->key);
154	* abort();
155	* }
156	* @endcode
157	*
158	* After you have finished reading the file, you must close it with
159	* avformat_close_input(). It will free everything associated with the file.
160	*
161	* @section lavf_decoding_read Reading from an opened file
162	* Reading data from an opened AVFormatContext is done by repeatedly calling
163	* av_read_frame() on it. Each call, if successful, will return an AVPacket
164	* containing encoded data for one AVStream, identified by
165	* AVPacket.stream_index. This packet may be passed straight into the libavcodec
166	* decoding functions avcodec_send_packet() or avcodec_decode_subtitle2() if the
167	* caller wishes to decode the data.
168	*
169	* AVPacket.pts, AVPacket.dts and AVPacket.duration timing information will be
170	* set if known. They may also be unset (i.e. AV_NOPTS_VALUE for
171	* pts/dts, 0 for duration) if the stream does not provide them. The timing
172	* information will be in AVStream.time_base units, i.e. it has to be
173	* multiplied by the timebase to convert them to seconds.
174	*
175	* If AVPacket.buf is set on the returned packet, then the packet is
176	* allocated dynamically and the user may keep it indefinitely.
177	* Otherwise, if AVPacket.buf is NULL, the packet data is backed by a
178	* static storage somewhere inside the demuxer and the packet is only valid
179	* until the next av_read_frame() call or closing the file. If the caller
180	* requires a longer lifetime, av_dup_packet() will make an av_malloc()ed copy
181	* of it.
182	* In both cases, the packet must be freed with av_packet_unref() when it is no
183	* longer needed.
184	*
185	* @section lavf_decoding_seek Seeking
186	* @}
187	*
188	* @defgroup lavf_encoding Muxing
189	* @{
190	* Muxers take encoded data in the form of @ref AVPacket "AVPackets" and write
191	* it into files or other output bytestreams in the specified container format.
192	*
193	* The main API functions for muxing are avformat_write_header() for writing the
194	* file header, av_write_frame() / av_interleaved_write_frame() for writing the
195	* packets and av_write_trailer() for finalizing the file.
196	*
197	* At the beginning of the muxing process, the caller must first call
198	* avformat_alloc_context() to create a muxing context. The caller then sets up
199	* the muxer by filling the various fields in this context:
200	*
201	* - The @ref AVFormatContext.oformat "oformat" field must be set to select the
202	* muxer that will be used.
203	* - Unless the format is of the AVFMT_NOFILE type, the @ref AVFormatContext.pb
204	* "pb" field must be set to an opened IO context, either returned from
205	* avio_open2() or a custom one.
206	* - Unless the format is of the AVFMT_NOSTREAMS type, at least one stream must
207	* be created with the avformat_new_stream() function. The caller should fill
208	* the @ref AVStream.codecpar "stream codec parameters" information, such as the
209	* codec @ref AVCodecParameters.codec_type "type", @ref AVCodecParameters.codec_id
210	* "id" and other parameters (e.g. width / height, the pixel or sample format,
211	* etc.) as known. The @ref AVStream.time_base "stream timebase" should
212	* be set to the timebase that the caller desires to use for this stream (note
213	* that the timebase actually used by the muxer can be different, as will be
214	* described later).
215	* - It is advised to manually initialize only the relevant fields in
216	* AVCodecParameters, rather than using @ref avcodec_parameters_copy() during
217	* remuxing: there is no guarantee that the codec context values remain valid
218	* for both input and output format contexts.
219	* - The caller may fill in additional information, such as @ref
220	* AVFormatContext.metadata "global" or @ref AVStream.metadata "per-stream"
221	* metadata, @ref AVFormatContext.chapters "chapters", @ref
222	* AVFormatContext.programs "programs", etc. as described in the
223	* AVFormatContext documentation. Whether such information will actually be
224	* stored in the output depends on what the container format and the muxer
225	* support.
226	*
227	* When the muxing context is fully set up, the caller must call
228	* avformat_write_header() to initialize the muxer internals and write the file
229	* header. Whether anything actually is written to the IO context at this step
230	* depends on the muxer, but this function must always be called. Any muxer
231	* private options must be passed in the options parameter to this function.
232	*
233	* The data is then sent to the muxer by repeatedly calling av_write_frame() or
234	* av_interleaved_write_frame() (consult those functions' documentation for
235	* discussion on the difference between them; only one of them may be used with
236	* a single muxing context, they should not be mixed). Do note that the timing
237	* information on the packets sent to the muxer must be in the corresponding
238	* AVStream's timebase. That timebase is set by the muxer (in the
239	* avformat_write_header() step) and may be different from the timebase
240	* requested by the caller.
241	*
242	* Once all the data has been written, the caller must call av_write_trailer()
243	* to flush any buffered packets and finalize the output file, then close the IO
244	* context (if any) and finally free the muxing context with
245	* avformat_free_context().
246	* @}
247	*
248	* @defgroup lavf_io I/O Read/Write
249	* @{
250	* @section lavf_io_dirlist Directory listing
251	* The directory listing API makes it possible to list files on remote servers.
252	*
253	* Some of possible use cases:
254	* - an "open file" dialog to choose files from a remote location,
255	* - a recursive media finder providing a player with an ability to play all
256	* files from a given directory.
257	*
258	* @subsection lavf_io_dirlist_open Opening a directory
259	* At first, a directory needs to be opened by calling avio_open_dir()
260	* supplied with a URL and, optionally, ::AVDictionary containing
261	* protocol-specific parameters. The function returns zero or positive
262	* integer and allocates AVIODirContext on success.
263	*
264	* @code
265	* AVIODirContext *ctx = NULL;
266	* if (avio_open_dir(&ctx, "smb://example.com/some_dir", NULL) < 0) {
267	* fprintf(stderr, "Cannot open directory.\n");
268	* abort();
269	* }
270	* @endcode
271	*
272	* This code tries to open a sample directory using smb protocol without
273	* any additional parameters.
274	*
275	* @subsection lavf_io_dirlist_read Reading entries
276	* Each directory's entry (i.e. file, another directory, anything else
277	* within ::AVIODirEntryType) is represented by AVIODirEntry.
278	* Reading consecutive entries from an opened AVIODirContext is done by
279	* repeatedly calling avio_read_dir() on it. Each call returns zero or
280	* positive integer if successful. Reading can be stopped right after the
281	* NULL entry has been read -- it means there are no entries left to be
282	* read. The following code reads all entries from a directory associated
283	* with ctx and prints their names to standard output.
284	* @code
285	* AVIODirEntry *entry = NULL;
286	* for (;;) {
287	* if (avio_read_dir(ctx, &entry) < 0) {
288	* fprintf(stderr, "Cannot list directory.\n");
289	* abort();
290	* }
291	* if (!entry)
292	* break;
293	* printf("%s\n", entry->name);
294	* avio_free_directory_entry(&entry);
295	* }
296	* @endcode
297	* @}
298	*
299	* @defgroup lavf_codec Demuxers
300	* @{
301	* @defgroup lavf_codec_native Native Demuxers
302	* @{
303	* @}
304	* @defgroup lavf_codec_wrappers External library wrappers
305	* @{
306	* @}
307	* @}
308	* @defgroup lavf_protos I/O Protocols
309	* @{
310	* @}
311	* @defgroup lavf_internal Internal
312	* @{
313	* @}
314	* @}
315	*/
316
317	#include <time.h>
318	#include <stdio.h> /* FILE */
319	#include "libavcodec/avcodec.h"
320	#include "libavutil/dict.h"
321	#include "libavutil/log.h"
322
323	#include "avio.h"
324	#include "libavformat/version.h"
325
326	struct AVFormatContext;
327
328	struct AVDeviceInfoList;
329	struct AVDeviceCapabilitiesQuery;
330
331	/**
332	* @defgroup metadata_api Public Metadata API
333	* @{
334	* @ingroup libavf
335	* The metadata API allows libavformat to export metadata tags to a client
336	* application when demuxing. Conversely it allows a client application to
337	* set metadata when muxing.
338	*
339	* Metadata is exported or set as pairs of key/value strings in the 'metadata'
340	* fields of the AVFormatContext, AVStream, AVChapter and AVProgram structs
341	* using the @ref lavu_dict "AVDictionary" API. Like all strings in FFmpeg,
342	* metadata is assumed to be UTF-8 encoded Unicode. Note that metadata
343	* exported by demuxers isn't checked to be valid UTF-8 in most cases.
344	*
345	* Important concepts to keep in mind:
346	* - Keys are unique; there can never be 2 tags with the same key. This is
347	* also meant semantically, i.e., a demuxer should not knowingly produce
348	* several keys that are literally different but semantically identical.
349	* E.g., key=Author5, key=Author6. In this example, all authors must be
350	* placed in the same tag.
351	* - Metadata is flat, not hierarchical; there are no subtags. If you
352	* want to store, e.g., the email address of the child of producer Alice
353	* and actor Bob, that could have key=alice_and_bobs_childs_email_address.
354	* - Several modifiers can be applied to the tag name. This is done by
355	* appending a dash character ('-') and the modifier name in the order
356	* they appear in the list below -- e.g. foo-eng-sort, not foo-sort-eng.
357	* - language -- a tag whose value is localized for a particular language
358	* is appended with the ISO 639-2/B 3-letter language code.
359	* For example: Author-ger=Michael, Author-eng=Mike
360	* The original/default language is in the unqualified "Author" tag.
361	* A demuxer should set a default if it sets any translated tag.
362	* - sorting -- a modified version of a tag that should be used for
363	* sorting will have '-sort' appended. E.g. artist="The Beatles",
364	* artist-sort="Beatles, The".
365	* - Some protocols and demuxers support metadata updates. After a successful
366	* call to av_read_packet(), AVFormatContext.event_flags or AVStream.event_flags
367	* will be updated to indicate if metadata changed. In order to detect metadata
368	* changes on a stream, you need to loop through all streams in the AVFormatContext
369	* and check their individual event_flags.
370	*
371	* - Demuxers attempt to export metadata in a generic format, however tags
372	* with no generic equivalents are left as they are stored in the container.
373	* Follows a list of generic tag names:
374	*
375	@verbatim
376	album -- name of the set this work belongs to
377	album_artist -- main creator of the set/album, if different from artist.
378	e.g. "Various Artists" for compilation albums.
379	artist -- main creator of the work
380	comment -- any additional description of the file.
381	composer -- who composed the work, if different from artist.
382	copyright -- name of copyright holder.
383	creation_time-- date when the file was created, preferably in ISO 8601.
384	date -- date when the work was created, preferably in ISO 8601.
385	disc -- number of a subset, e.g. disc in a multi-disc collection.
386	encoder -- name/settings of the software/hardware that produced the file.
387	encoded_by -- person/group who created the file.
388	filename -- original name of the file.
389	genre -- <self-evident>.
390	language -- main language in which the work is performed, preferably
391	in ISO 639-2 format. Multiple languages can be specified by
392	separating them with commas.
393	performer -- artist who performed the work, if different from artist.
394	E.g for "Also sprach Zarathustra", artist would be "Richard
395	Strauss" and performer "London Philharmonic Orchestra".
396	publisher -- name of the label/publisher.
397	service_name -- name of the service in broadcasting (channel name).
398	service_provider -- name of the service provider in broadcasting.
399	title -- name of the work.
400	track -- number of this work in the set, can be in form current/total.
401	variant_bitrate -- the total bitrate of the bitrate variant that the current stream is part of
402	@endverbatim
403	*
404	* Look in the examples section for an application example how to use the Metadata API.
405	*
406	* @}
407	*/
408
409	/* packet functions */
410
411
412	/**
413	* Allocate and read the payload of a packet and initialize its
414	* fields with default values.
415	*
416	* @param s associated IO context
417	* @param pkt packet
418	* @param size desired payload size
419	* @return >0 (read size) if OK, AVERROR_xxx otherwise
420	*/
421	int av_get_packet(AVIOContext *s, AVPacket *pkt, int size);
422
423
424	/**
425	* Read data and append it to the current content of the AVPacket.
426	* If pkt->size is 0 this is identical to av_get_packet.
427	* Note that this uses av_grow_packet and thus involves a realloc
428	* which is inefficient. Thus this function should only be used
429	* when there is no reasonable way to know (an upper bound of)
430	* the final size.
431	*
432	* @param s associated IO context
433	* @param pkt packet
434	* @param size amount of data to read
435	* @return >0 (read size) if OK, AVERROR_xxx otherwise, previous data
436	* will not be lost even if an error occurs.
437	*/
438	int av_append_packet(AVIOContext *s, AVPacket *pkt, int size);
439
440	#if FF_API_LAVF_FRAC
441	/*************************************************/
442	/* fractional numbers for exact pts handling */
443
444	/**
445	* The exact value of the fractional number is: 'val + num / den'.
446	* num is assumed to be 0 <= num < den.
447	*/
448	typedef struct AVFrac {
449	int64_t val, num, den;
450	} AVFrac;
451	#endif
452
453	/*************************************************/
454	/* input/output formats */
455
456	struct AVCodecTag;
457
458	/**
459	* This structure contains the data a format has to probe a file.
460	*/
461	typedef struct AVProbeData {
462	const char *filename;
463	unsigned char *buf; /**< Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero. */
464	int buf_size; /**< Size of buf except extra allocated bytes */
465	const char *mime_type; /**< mime_type, when known. */
466	} AVProbeData;
467
468	#define AVPROBE_SCORE_RETRY (AVPROBE_SCORE_MAX/4)
469	#define AVPROBE_SCORE_STREAM_RETRY (AVPROBE_SCORE_MAX/4-1)
470
471	#define AVPROBE_SCORE_EXTENSION 50 ///< score for file extension
472	#define AVPROBE_SCORE_MIME 75 ///< score for file mime type
473	#define AVPROBE_SCORE_MAX 100 ///< maximum score
474
475	#define AVPROBE_PADDING_SIZE 32 ///< extra allocated bytes at the end of the probe buffer
476
477	/// Demuxer will use avio_open, no opened file should be provided by the caller.
478	#define AVFMT_NOFILE 0x0001
479	#define AVFMT_NEEDNUMBER 0x0002 /**< Needs '%d' in filename. */
480	#define AVFMT_SHOW_IDS 0x0008 /**< Show format stream IDs numbers. */
481	#if FF_API_LAVF_FMT_RAWPICTURE
482	#define AVFMT_RAWPICTURE 0x0020 /**< Format wants AVPicture structure for
483	raw picture data. @deprecated Not used anymore */
484	#endif
485	#define AVFMT_GLOBALHEADER 0x0040 /**< Format wants global header. */
486	#define AVFMT_NOTIMESTAMPS 0x0080 /**< Format does not need / have any timestamps. */
487	#define AVFMT_GENERIC_INDEX 0x0100 /**< Use generic index building code. */
488	#define AVFMT_TS_DISCONT 0x0200 /**< Format allows timestamp discontinuities. Note, muxers always require valid (monotone) timestamps */
489	#define AVFMT_VARIABLE_FPS 0x0400 /**< Format allows variable fps. */
490	#define AVFMT_NODIMENSIONS 0x0800 /**< Format does not need width/height */
491	#define AVFMT_NOSTREAMS 0x1000 /**< Format does not require any streams */
492	#define AVFMT_NOBINSEARCH 0x2000 /**< Format does not allow to fall back on binary search via read_timestamp */
493	#define AVFMT_NOGENSEARCH 0x4000 /**< Format does not allow to fall back on generic search */
494	#define AVFMT_NO_BYTE_SEEK 0x8000 /**< Format does not allow seeking by bytes */
495	#define AVFMT_ALLOW_FLUSH 0x10000 /**< Format allows flushing. If not set, the muxer will not receive a NULL packet in the write_packet function. */
496	#define AVFMT_TS_NONSTRICT 0x20000 /**< Format does not require strictly
497	increasing timestamps, but they must
498	still be monotonic */
499	#define AVFMT_TS_NEGATIVE 0x40000 /**< Format allows muxing negative
500	timestamps. If not set the timestamp
501	will be shifted in av_write_frame and
502	av_interleaved_write_frame so they
503	start from 0.
504	The user or muxer can override this through
505	AVFormatContext.avoid_negative_ts
506	*/
507
508	#define AVFMT_SEEK_TO_PTS 0x4000000 /**< Seeking is based on PTS */
509
510	/**
511	* @addtogroup lavf_encoding
512	* @{
513	*/
514	typedef struct AVOutputFormat {
515	const char *name;
516	/**
517	* Descriptive name for the format, meant to be more human-readable
518	* than name. You should use the NULL_IF_CONFIG_SMALL() macro
519	* to define it.
520	*/
521	const char *long_name;
522	const char *mime_type;
523	const char *extensions; /**< comma-separated filename extensions */
524	/* output support */
525	enum AVCodecID audio_codec; /**< default audio codec */
526	enum AVCodecID video_codec; /**< default video codec */
527	enum AVCodecID subtitle_codec; /**< default subtitle codec */
528	/**
529	* can use flags: AVFMT_NOFILE, AVFMT_NEEDNUMBER,
530	* AVFMT_GLOBALHEADER, AVFMT_NOTIMESTAMPS, AVFMT_VARIABLE_FPS,
531	* AVFMT_NODIMENSIONS, AVFMT_NOSTREAMS, AVFMT_ALLOW_FLUSH,
532	* AVFMT_TS_NONSTRICT, AVFMT_TS_NEGATIVE
533	*/
534	int flags;
535
536	/**
537	* List of supported codec_id-codec_tag pairs, ordered by "better
538	* choice first". The arrays are all terminated by AV_CODEC_ID_NONE.
539	*/
540	const struct AVCodecTag * const *codec_tag;
541
542
543	const AVClass *priv_class; ///< AVClass for the private context
544
545	/*****************************************************************
546	* No fields below this line are part of the public API. They
547	* may not be used outside of libavformat and can be changed and
548	* removed at will.
549	* New public fields should be added right above.
550	*****************************************************************
551	*/
552	struct AVOutputFormat *next;
553	/**
554	* size of private data so that it can be allocated in the wrapper
555	*/
556	int priv_data_size;
557
558	int (*write_header)(struct AVFormatContext *);
559	/**
560	* Write a packet. If AVFMT_ALLOW_FLUSH is set in flags,
561	* pkt can be NULL in order to flush data buffered in the muxer.
562	* When flushing, return 0 if there still is more data to flush,
563	* or 1 if everything was flushed and there is no more buffered
564	* data.
565	*/
566	int (*write_packet)(struct AVFormatContext *, AVPacket *pkt);
567	int (*write_trailer)(struct AVFormatContext *);
568	/**
569	* Currently only used to set pixel format if not YUV420P.
570	*/
571	int (*interleave_packet)(struct AVFormatContext *, AVPacket *out,
572	AVPacket *in, int flush);
573	/**
574	* Test if the given codec can be stored in this container.
575	*
576	* @return 1 if the codec is supported, 0 if it is not.
577	* A negative number if unknown.
578	* MKTAG('A', 'P', 'I', 'C') if the codec is only supported as AV_DISPOSITION_ATTACHED_PIC
579	*/
580	int (*query_codec)(enum AVCodecID id, int std_compliance);
581
582	void (*get_output_timestamp)(struct AVFormatContext *s, int stream,
583	int64_t *dts, int64_t *wall);
584	/**
585	* Allows sending messages from application to device.
586	*/
587	int (*control_message)(struct AVFormatContext *s, int type,
588	void *data, size_t data_size);
589
590	/**
591	* Write an uncoded AVFrame.
592	*
593	* See av_write_uncoded_frame() for details.
594	*
595	* The library will free *frame afterwards, but the muxer can prevent it
596	* by setting the pointer to NULL.
597	*/
598	int (*write_uncoded_frame)(struct AVFormatContext *, int stream_index,
599	AVFrame **frame, unsigned flags);
600	/**
601	* Returns device list with it properties.
602	* @see avdevice_list_devices() for more details.
603	*/
604	int (*get_device_list)(struct AVFormatContext *s, struct AVDeviceInfoList *device_list);
605	/**
606	* Initialize device capabilities submodule.
607	* @see avdevice_capabilities_create() for more details.
608	*/
609	int (*create_device_capabilities)(struct AVFormatContext *s, struct AVDeviceCapabilitiesQuery *caps);
610	/**
611	* Free device capabilities submodule.
612	* @see avdevice_capabilities_free() for more details.
613	*/
614	int (*free_device_capabilities)(struct AVFormatContext *s, struct AVDeviceCapabilitiesQuery *caps);
615	enum AVCodecID data_codec; /**< default data codec */
616	/**
617	* Initialize format. May allocate data here, and set any AVFormatContext or
618	* AVStream parameters that need to be set before packets are sent.
619	* This method must not write output.
620	*
621	* Return 0 if streams were fully configured, 1 if not, negative AVERROR on failure
622	*
623	* Any allocations made here must be freed in deinit().
624	*/
625	int (*init)(struct AVFormatContext *);
626	/**
627	* Deinitialize format. If present, this is called whenever the muxer is being
628	* destroyed, regardless of whether or not the header has been written.
629	*
630	* If a trailer is being written, this is called after write_trailer().
631	*
632	* This is called if init() fails as well.
633	*/
634	void (*deinit)(struct AVFormatContext *);
635	/**
636	* Set up any necessary bitstream filtering and extract any extra data needed
637	* for the global header.
638	* Return 0 if more packets from this stream must be checked; 1 if not.
639	*/
640	int (*check_bitstream)(struct AVFormatContext *, const AVPacket *pkt);
641	} AVOutputFormat;
642	/**
643	* @}
644	*/
645
646	/**
647	* @addtogroup lavf_decoding
648	* @{
649	*/
650	typedef struct AVInputFormat {
651	/**
652	* A comma separated list of short names for the format. New names
653	* may be appended with a minor bump.
654	*/
655	const char *name;
656
657	/**
658	* Descriptive name for the format, meant to be more human-readable
659	* than name. You should use the NULL_IF_CONFIG_SMALL() macro
660	* to define it.
661	*/
662	const char *long_name;
663
664	/**
665	* Can use flags: AVFMT_NOFILE, AVFMT_NEEDNUMBER, AVFMT_SHOW_IDS,
666	* AVFMT_GENERIC_INDEX, AVFMT_TS_DISCONT, AVFMT_NOBINSEARCH,
667	* AVFMT_NOGENSEARCH, AVFMT_NO_BYTE_SEEK, AVFMT_SEEK_TO_PTS.
668	*/
669	int flags;
670
671	/**
672	* If extensions are defined, then no probe is done. You should
673	* usually not use extension format guessing because it is not
674	* reliable enough
675	*/
676	const char *extensions;
677
678	const struct AVCodecTag * const *codec_tag;
679
680	const AVClass *priv_class; ///< AVClass for the private context
681
682	/**
683	* Comma-separated list of mime types.
684	* It is used check for matching mime types while probing.
685	* @see av_probe_input_format2
686	*/
687	const char *mime_type;
688
689	/*****************************************************************
690	* No fields below this line are part of the public API. They
691	* may not be used outside of libavformat and can be changed and
692	* removed at will.
693	* New public fields should be added right above.
694	*****************************************************************
695	*/
696	struct AVInputFormat *next;
697
698	/**
699	* Raw demuxers store their codec ID here.
700	*/
701	int raw_codec_id;
702
703	/**
704	* Size of private data so that it can be allocated in the wrapper.
705	*/
706	int priv_data_size;
707
708	/**
709	* Tell if a given file has a chance of being parsed as this format.
710	* The buffer provided is guaranteed to be AVPROBE_PADDING_SIZE bytes
711	* big so you do not have to check for that unless you need more.
712	*/
713	int (*read_probe)(AVProbeData *);
714
715	/**
716	* Read the format header and initialize the AVFormatContext
717	* structure. Return 0 if OK. 'avformat_new_stream' should be
718	* called to create new streams.
719	*/
720	int (*read_header)(struct AVFormatContext *);
721
722	/**
723	* Read one packet and put it in 'pkt'. pts and flags are also
724	* set. 'avformat_new_stream' can be called only if the flag
725	* AVFMTCTX_NOHEADER is used and only in the calling thread (not in a
726	* background thread).
727	* @return 0 on success, < 0 on error.
728	* When returning an error, pkt must not have been allocated
729	* or must be freed before returning
730	*/
731	int (*read_packet)(struct AVFormatContext *, AVPacket *pkt);
732
733	/**
734	* Close the stream. The AVFormatContext and AVStreams are not
735	* freed by this function
736	*/
737	int (*read_close)(struct AVFormatContext *);
738
739	/**
740	* Seek to a given timestamp relative to the frames in
741	* stream component stream_index.
742	* @param stream_index Must not be -1.
743	* @param flags Selects which direction should be preferred if no exact
744	* match is available.
745	* @return >= 0 on success (but not necessarily the new offset)
746	*/
747	int (*read_seek)(struct AVFormatContext *,
748	int stream_index, int64_t timestamp, int flags);
749
750	/**
751	* Get the next timestamp in stream[stream_index].time_base units.
752	* @return the timestamp or AV_NOPTS_VALUE if an error occurred
753	*/
754	int64_t (*read_timestamp)(struct AVFormatContext *s, int stream_index,
755	int64_t *pos, int64_t pos_limit);
756
757	/**
758	* Start/resume playing - only meaningful if using a network-based format
759	* (RTSP).
760	*/
761	int (*read_play)(struct AVFormatContext *);
762
763	/**
764	* Pause playing - only meaningful if using a network-based format
765	* (RTSP).
766	*/
767	int (*read_pause)(struct AVFormatContext *);
768
769	/**
770	* Seek to timestamp ts.
771	* Seeking will be done so that the point from which all active streams
772	* can be presented successfully will be closest to ts and within min/max_ts.
773	* Active streams are all streams that have AVStream.discard < AVDISCARD_ALL.
774	*/
775	int (*read_seek2)(struct AVFormatContext *s, int stream_index, int64_t min_ts, int64_t ts, int64_t max_ts, int flags);
776
777	/**
778	* Returns device list with it properties.
779	* @see avdevice_list_devices() for more details.
780	*/
781	int (*get_device_list)(struct AVFormatContext *s, struct AVDeviceInfoList *device_list);
782
783	/**
784	* Initialize device capabilities submodule.
785	* @see avdevice_capabilities_create() for more details.
786	*/
787	int (*create_device_capabilities)(struct AVFormatContext *s, struct AVDeviceCapabilitiesQuery *caps);
788
789	/**
790	* Free device capabilities submodule.
791	* @see avdevice_capabilities_free() for more details.
792	*/
793	int (*free_device_capabilities)(struct AVFormatContext *s, struct AVDeviceCapabilitiesQuery *caps);
794	} AVInputFormat;
795	/**
796	* @}
797	*/
798
799	enum AVStreamParseType {
800	AVSTREAM_PARSE_NONE,
801	AVSTREAM_PARSE_FULL, /**< full parsing and repack */
802	AVSTREAM_PARSE_HEADERS, /**< Only parse headers, do not repack. */
803	AVSTREAM_PARSE_TIMESTAMPS, /**< full parsing and interpolation of timestamps for frames not starting on a packet boundary */
804	AVSTREAM_PARSE_FULL_ONCE, /**< full parsing and repack of the first frame only, only implemented for H.264 currently */
805	AVSTREAM_PARSE_FULL_RAW=MKTAG(0,'R','A','W'), /**< full parsing and repack with timestamp and position generation by parser for raw
806	this assumes that each packet in the file contains no demuxer level headers and
807	just codec level data, otherwise position generation would fail */
808	};
809
810	typedef struct AVIndexEntry {
811	int64_t pos;
812	int64_t timestamp; /**<
813	* Timestamp in AVStream.time_base units, preferably the time from which on correctly decoded frames are available
814	* when seeking to this entry. That means preferable PTS on keyframe based formats.
815	* But demuxers can choose to store a different timestamp, if it is more convenient for the implementation or nothing better
816	* is known
817	*/
818	#define AVINDEX_KEYFRAME 0x0001
819	#define AVINDEX_DISCARD_FRAME 0x0002 /**
820	* Flag is used to indicate which frame should be discarded after decoding.
821	*/
822	int flags:2;
823	int size:30; //Yeah, trying to keep the size of this small to reduce memory requirements (it is 24 vs. 32 bytes due to possible 8-byte alignment).
824	int min_distance; /**< Minimum distance between this and the previous keyframe, used to avoid unneeded searching. */
825	} AVIndexEntry;
826
827	#define AV_DISPOSITION_DEFAULT 0x0001
828	#define AV_DISPOSITION_DUB 0x0002
829	#define AV_DISPOSITION_ORIGINAL 0x0004
830	#define AV_DISPOSITION_COMMENT 0x0008
831	#define AV_DISPOSITION_LYRICS 0x0010
832	#define AV_DISPOSITION_KARAOKE 0x0020
833
834	/**
835	* Track should be used during playback by default.
836	* Useful for subtitle track that should be displayed
837	* even when user did not explicitly ask for subtitles.
838	*/
839	#define AV_DISPOSITION_FORCED 0x0040
840	#define AV_DISPOSITION_HEARING_IMPAIRED 0x0080 /**< stream for hearing impaired audiences */
841	#define AV_DISPOSITION_VISUAL_IMPAIRED 0x0100 /**< stream for visual impaired audiences */
842	#define AV_DISPOSITION_CLEAN_EFFECTS 0x0200 /**< stream without voice */
843	/**
844	* The stream is stored in the file as an attached picture/"cover art" (e.g.
845	* APIC frame in ID3v2). The first (usually only) packet associated with it
846	* will be returned among the first few packets read from the file unless
847	* seeking takes place. It can also be accessed at any time in
848	* AVStream.attached_pic.
849	*/
850	#define AV_DISPOSITION_ATTACHED_PIC 0x0400
851	/**
852	* The stream is sparse, and contains thumbnail images, often corresponding
853	* to chapter markers. Only ever used with AV_DISPOSITION_ATTACHED_PIC.
854	*/
855	#define AV_DISPOSITION_TIMED_THUMBNAILS 0x0800
856
857	typedef struct AVStreamInternal AVStreamInternal;
858
859	/**
860	* To specify text track kind (different from subtitles default).
861	*/
862	#define AV_DISPOSITION_CAPTIONS 0x10000
863	#define AV_DISPOSITION_DESCRIPTIONS 0x20000
864	#define AV_DISPOSITION_METADATA 0x40000
865
866	/**
867	* Options for behavior on timestamp wrap detection.
868	*/
869	#define AV_PTS_WRAP_IGNORE 0 ///< ignore the wrap
870	#define AV_PTS_WRAP_ADD_OFFSET 1 ///< add the format specific offset on wrap detection
871	#define AV_PTS_WRAP_SUB_OFFSET -1 ///< subtract the format specific offset on wrap detection
872
873	/**
874	* Stream structure.
875	* New fields can be added to the end with minor version bumps.
876	* Removal, reordering and changes to existing fields require a major
877	* version bump.
878	* sizeof(AVStream) must not be used outside libav*.
879	*/
880	typedef struct AVStream {
881	int index; /**< stream index in AVFormatContext */
882	/**
883	* Format-specific stream ID.
884	* decoding: set by libavformat
885	* encoding: set by the user, replaced by libavformat if left unset
886	*/
887	int id;
888	#if FF_API_LAVF_AVCTX
889	/**
890	* @deprecated use the codecpar struct instead
891	*/
892	attribute_deprecated
893	AVCodecContext *codec;
894	#endif
895	void *priv_data;
896
897	#if FF_API_LAVF_FRAC
898	/**
899	* @deprecated this field is unused
900	*/
901	attribute_deprecated
902	struct AVFrac pts;
903	#endif
904
905	/**
906	* This is the fundamental unit of time (in seconds) in terms
907	* of which frame timestamps are represented.
908	*
909	* decoding: set by libavformat
910	* encoding: May be set by the caller before avformat_write_header() to
911	* provide a hint to the muxer about the desired timebase. In
912	* avformat_write_header(), the muxer will overwrite this field
913	* with the timebase that will actually be used for the timestamps
914	* written into the file (which may or may not be related to the
915	* user-provided one, depending on the format).
916	*/
917	AVRational time_base;
918
919	/**
920	* Decoding: pts of the first frame of the stream in presentation order, in stream time base.
921	* Only set this if you are absolutely 100% sure that the value you set
922	* it to really is the pts of the first frame.
923	* This may be undefined (AV_NOPTS_VALUE).
924	* @note The ASF header does NOT contain a correct start_time the ASF
925	* demuxer must NOT set this.
926	*/
927	int64_t start_time;
928
929	/**
930	* Decoding: duration of the stream, in stream time base.
931	* If a source file does not specify a duration, but does specify
932	* a bitrate, this value will be estimated from bitrate and file size.
933	*
934	* Encoding: May be set by the caller before avformat_write_header() to
935	* provide a hint to the muxer about the estimated duration.
936	*/
937	int64_t duration;
938
939	int64_t nb_frames; ///< number of frames in this stream if known or 0
940
941	int disposition; /**< AV_DISPOSITION_* bit field */
942
943	enum AVDiscard discard; ///< Selects which packets can be discarded at will and do not need to be demuxed.
944
945	/**
946	* sample aspect ratio (0 if unknown)
947	* - encoding: Set by user.
948	* - decoding: Set by libavformat.
949	*/
950	AVRational sample_aspect_ratio;
951
952	AVDictionary *metadata;
953
954	/**
955	* Average framerate
956	*
957	* - demuxing: May be set by libavformat when creating the stream or in
958	* avformat_find_stream_info().
959	* - muxing: May be set by the caller before avformat_write_header().
960	*/
961	AVRational avg_frame_rate;
962
963	/**
964	* For streams with AV_DISPOSITION_ATTACHED_PIC disposition, this packet
965	* will contain the attached picture.
966	*
967	* decoding: set by libavformat, must not be modified by the caller.
968	* encoding: unused
969	*/
970	AVPacket attached_pic;
971
972	/**
973	* An array of side data that applies to the whole stream (i.e. the
974	* container does not allow it to change between packets).
975	*
976	* There may be no overlap between the side data in this array and side data
977	* in the packets. I.e. a given side data is either exported by the muxer
978	* (demuxing) / set by the caller (muxing) in this array, then it never
979	* appears in the packets, or the side data is exported / sent through
980	* the packets (always in the first packet where the value becomes known or
981	* changes), then it does not appear in this array.
982	*
983	* - demuxing: Set by libavformat when the stream is created.
984	* - muxing: May be set by the caller before avformat_write_header().
985	*
986	* Freed by libavformat in avformat_free_context().
987	*
988	* @see av_format_inject_global_side_data()
989	*/
990	AVPacketSideData *side_data;
991	/**
992	* The number of elements in the AVStream.side_data array.
993	*/
994	int nb_side_data;
995
996	/**
997	* Flags for the user to detect events happening on the stream. Flags must
998	* be cleared by the user once the event has been handled.
999	* A combination of AVSTREAM_EVENT_FLAG_*.
1000	*/
1001	int event_flags;
1002	#define AVSTREAM_EVENT_FLAG_METADATA_UPDATED 0x0001 ///< The call resulted in updated metadata.
1003
1004	/*****************************************************************
1005	* All fields below this line are not part of the public API. They
1006	* may not be used outside of libavformat and can be changed and
1007	* removed at will.
1008	* Internal note: be aware that physically removing these fields
1009	* will break ABI. Replace removed fields with dummy fields, and
1010	* add new fields to AVStreamInternal.
1011	*****************************************************************
1012	*/
1013
1014	/**
1015	* Stream information used internally by avformat_find_stream_info()
1016	*/
1017	#define MAX_STD_TIMEBASES (30*12+30+3+6)
1018	struct {
1019	int64_t last_dts;
1020	int64_t duration_gcd;
1021	int duration_count;
1022	int64_t rfps_duration_sum;
1023	double (*duration_error)[2][MAX_STD_TIMEBASES];
1024	int64_t codec_info_duration;
1025	int64_t codec_info_duration_fields;
1026
1027	/**
1028	* 0 -> decoder has not been searched for yet.
1029	* >0 -> decoder found
1030	* <0 -> decoder with codec_id == -found_decoder has not been found
1031	*/
1032	int found_decoder;
1033
1034	int64_t last_duration;
1035
1036	/**
1037	* Those are used for average framerate estimation.
1038	*/
1039	int64_t fps_first_dts;
1040	int fps_first_dts_idx;
1041	int64_t fps_last_dts;
1042	int fps_last_dts_idx;
1043
1044	} *info;
1045
1046	int pts_wrap_bits; /**< number of bits in pts (used for wrapping control) */
1047
1048	// Timestamp generation support:
1049	/**
1050	* Timestamp corresponding to the last dts sync point.
1051	*
1052	* Initialized when AVCodecParserContext.dts_sync_point >= 0 and
1053	* a DTS is received from the underlying container. Otherwise set to
1054	* AV_NOPTS_VALUE by default.
1055	*/
1056	int64_t first_dts;
1057	int64_t cur_dts;
1058	int64_t last_IP_pts;
1059	int last_IP_duration;
1060
1061	/**
1062	* Number of packets to buffer for codec probing
1063	*/
1064	int probe_packets;
1065
1066	/**
1067	* Number of frames that have been demuxed during avformat_find_stream_info()
1068	*/
1069	int codec_info_nb_frames;
1070
1071	/* av_read_frame() support */
1072	enum AVStreamParseType need_parsing;
1073	struct AVCodecParserContext *parser;
1074
1075	/**
1076	* last packet in packet_buffer for this stream when muxing.
1077	*/
1078	struct AVPacketList *last_in_packet_buffer;
1079	AVProbeData probe_data;
1080	#define MAX_REORDER_DELAY 16
1081	int64_t pts_buffer[MAX_REORDER_DELAY+1];
1082
1083	AVIndexEntry *index_entries; /**< Only used if the format does not
1084	support seeking natively. */
1085	int nb_index_entries;
1086	unsigned int index_entries_allocated_size;
1087
1088	/**
1089	* Real base framerate of the stream.
1090	* This is the lowest framerate with which all timestamps can be
1091	* represented accurately (it is the least common multiple of all
1092	* framerates in the stream). Note, this value is just a guess!
1093	* For example, if the time base is 1/90000 and all frames have either
1094	* approximately 3600 or 1800 timer ticks, then r_frame_rate will be 50/1.
1095	*
1096	* Code outside avformat should access this field using:
1097	* av_stream_get/set_r_frame_rate(stream)
1098	*/
1099	AVRational r_frame_rate;
1100
1101	/**
1102	* Stream Identifier
1103	* This is the MPEG-TS stream identifier +1
1104	* 0 means unknown
1105	*/
1106	int stream_identifier;
1107
1108	int64_t interleaver_chunk_size;
1109	int64_t interleaver_chunk_duration;
1110
1111	/**
1112	* stream probing state
1113	* -1 -> probing finished
1114	* 0 -> no probing requested
1115	* rest -> perform probing with request_probe being the minimum score to accept.
1116	* NOT PART OF PUBLIC API
1117	*/
1118	int request_probe;
1119	/**
1120	* Indicates that everything up to the next keyframe
1121	* should be discarded.
1122	*/
1123	int skip_to_keyframe;
1124
1125	/**
1126	* Number of samples to skip at the start of the frame decoded from the next packet.
1127	*/
1128	int skip_samples;
1129
1130	/**
1131	* If not 0, the number of samples that should be skipped from the start of
1132	* the stream (the samples are removed from packets with pts==0, which also
1133	* assumes negative timestamps do not happen).
1134	* Intended for use with formats such as mp3 with ad-hoc gapless audio
1135	* support.
1136	*/
1137	int64_t start_skip_samples;
1138
1139	/**
1140	* If not 0, the first audio sample that should be discarded from the stream.
1141	* This is broken by design (needs global sample count), but can't be
1142	* avoided for broken by design formats such as mp3 with ad-hoc gapless
1143	* audio support.
1144	*/
1145	int64_t first_discard_sample;
1146
1147	/**
1148	* The sample after last sample that is intended to be discarded after
1149	* first_discard_sample. Works on frame boundaries only. Used to prevent
1150	* early EOF if the gapless info is broken (considered concatenated mp3s).
1151	*/
1152	int64_t last_discard_sample;
1153
1154	/**
1155	* Number of internally decoded frames, used internally in libavformat, do not access
1156	* its lifetime differs from info which is why it is not in that structure.
1157	*/
1158	int nb_decoded_frames;
1159
1160	/**
1161	* Timestamp offset added to timestamps before muxing
1162	* NOT PART OF PUBLIC API
1163	*/
1164	int64_t mux_ts_offset;
1165
1166	/**
1167	* Internal data to check for wrapping of the time stamp
1168	*/
1169	int64_t pts_wrap_reference;
1170
1171	/**
1172	* Options for behavior, when a wrap is detected.
1173	*
1174	* Defined by AV_PTS_WRAP_ values.
1175	*
1176	* If correction is enabled, there are two possibilities:
1177	* If the first time stamp is near the wrap point, the wrap offset
1178	* will be subtracted, which will create negative time stamps.
1179	* Otherwise the offset will be added.
1180	*/
1181	int pts_wrap_behavior;
1182
1183	/**
1184	* Internal data to prevent doing update_initial_durations() twice
1185	*/
1186	int update_initial_durations_done;
1187
1188	/**
1189	* Internal data to generate dts from pts
1190	*/
1191	int64_t pts_reorder_error[MAX_REORDER_DELAY+1];
1192	uint8_t pts_reorder_error_count[MAX_REORDER_DELAY+1];
1193
1194	/**
1195	* Internal data to analyze DTS and detect faulty mpeg streams
1196	*/
1197	int64_t last_dts_for_order_check;
1198	uint8_t dts_ordered;
1199	uint8_t dts_misordered;
1200
1201	/**
1202	* Internal data to inject global side data
1203	*/
1204	int inject_global_side_data;
1205
1206	/*****************************************************************
1207	* All fields above this line are not part of the public API.
1208	* Fields below are part of the public API and ABI again.
1209	*****************************************************************
1210	*/
1211
1212	/**
1213	* String containing paris of key and values describing recommended encoder configuration.
1214	* Paris are separated by ','.
1215	* Keys are separated from values by '='.
1216	*/
1217	char *recommended_encoder_configuration;
1218
1219	/**
1220	* display aspect ratio (0 if unknown)
1221	* - encoding: unused
1222	* - decoding: Set by libavformat to calculate sample_aspect_ratio internally
1223	*/
1224	AVRational display_aspect_ratio;
1225
1226	struct FFFrac *priv_pts;
1227
1228	/**
1229	* An opaque field for libavformat internal usage.
1230	* Must not be accessed in any way by callers.
1231	*/
1232	AVStreamInternal *internal;
1233
1234	/*
1235	* Codec parameters associated with this stream. Allocated and freed by
1236	* libavformat in avformat_new_stream() and avformat_free_context()
1237	* respectively.
1238	*
1239	* - demuxing: filled by libavformat on stream creation or in
1240	* avformat_find_stream_info()
1241	* - muxing: filled by the caller before avformat_write_header()
1242	*/
1243	AVCodecParameters *codecpar;
1244	} AVStream;
1245
1246	AVRational av_stream_get_r_frame_rate(const AVStream *s);
1247	void av_stream_set_r_frame_rate(AVStream *s, AVRational r);
1248	struct AVCodecParserContext *av_stream_get_parser(const AVStream *s);
1249	char* av_stream_get_recommended_encoder_configuration(const AVStream *s);
1250	void av_stream_set_recommended_encoder_configuration(AVStream *s, char *configuration);
1251
1252	/**
1253	* Returns the pts of the last muxed packet + its duration
1254	*
1255	* the retuned value is undefined when used with a demuxer.
1256	*/
1257	int64_t av_stream_get_end_pts(const AVStream *st);
1258
1259	#define AV_PROGRAM_RUNNING 1
1260
1261	/**
1262	* New fields can be added to the end with minor version bumps.
1263	* Removal, reordering and changes to existing fields require a major
1264	* version bump.
1265	* sizeof(AVProgram) must not be used outside libav*.
1266	*/
1267	typedef struct AVProgram {
1268	int id;
1269	int flags;
1270	enum AVDiscard discard; ///< selects which program to discard and which to feed to the caller
1271	unsigned int *stream_index;
1272	unsigned int nb_stream_indexes;
1273	AVDictionary *metadata;
1274
1275	int program_num;
1276	int pmt_pid;
1277	int pcr_pid;
1278
1279	/*****************************************************************
1280	* All fields below this line are not part of the public API. They
1281	* may not be used outside of libavformat and can be changed and
1282	* removed at will.
1283	* New public fields should be added right above.
1284	*****************************************************************
1285	*/
1286	int64_t start_time;
1287	int64_t end_time;
1288
1289	int64_t pts_wrap_reference; ///< reference dts for wrap detection
1290	int pts_wrap_behavior; ///< behavior on wrap detection
1291	} AVProgram;
1292
1293	#define AVFMTCTX_NOHEADER 0x0001 /**< signal that no header is present
1294	(streams are added dynamically) */
1295
1296	typedef struct AVChapter {
1297	int id; ///< unique ID to identify the chapter
1298	AVRational time_base; ///< time base in which the start/end timestamps are specified
1299	int64_t start, end; ///< chapter start/end time in time_base units
1300	AVDictionary *metadata;
1301	} AVChapter;
1302
1303
1304	/**
1305	* Callback used by devices to communicate with application.
1306	*/
1307	typedef int (*av_format_control_message)(struct AVFormatContext *s, int type,
1308	void *data, size_t data_size);
1309
1310	typedef int (*AVOpenCallback)(struct AVFormatContext *s, AVIOContext **pb, const char *url, int flags,
1311	const AVIOInterruptCB *int_cb, AVDictionary **options);
1312
1313	/**
1314	* The duration of a video can be estimated through various ways, and this enum can be used
1315	* to know how the duration was estimated.
1316	*/
1317	enum AVDurationEstimationMethod {
1318	AVFMT_DURATION_FROM_PTS, ///< Duration accurately estimated from PTSes
1319	AVFMT_DURATION_FROM_STREAM, ///< Duration estimated from a stream with a known duration
1320	AVFMT_DURATION_FROM_BITRATE ///< Duration estimated from bitrate (less accurate)
1321	};
1322
1323	typedef struct AVFormatInternal AVFormatInternal;
1324
1325	/**
1326	* Format I/O context.
1327	* New fields can be added to the end with minor version bumps.
1328	* Removal, reordering and changes to existing fields require a major
1329	* version bump.
1330	* sizeof(AVFormatContext) must not be used outside libav*, use
1331	* avformat_alloc_context() to create an AVFormatContext.
1332	*
1333	* Fields can be accessed through AVOptions (av_opt*),
1334	* the name string used matches the associated command line parameter name and
1335	* can be found in libavformat/options_table.h.
1336	* The AVOption/command line parameter names differ in some cases from the C
1337	* structure field names for historic reasons or brevity.
1338	*/
1339	typedef struct AVFormatContext {
1340	/**
1341	* A class for logging and @ref avoptions. Set by avformat_alloc_context().
1342	* Exports (de)muxer private options if they exist.
1343	*/
1344	const AVClass *av_class;
1345
1346	/**
1347	* The input container format.
1348	*
1349	* Demuxing only, set by avformat_open_input().
1350	*/
1351	struct AVInputFormat *iformat;
1352
1353	/**
1354	* The output container format.
1355	*
1356	* Muxing only, must be set by the caller before avformat_write_header().
1357	*/
1358	struct AVOutputFormat *oformat;
1359
1360	/**
1361	* Format private data. This is an AVOptions-enabled struct
1362	* if and only if iformat/oformat.priv_class is not NULL.
1363	*
1364	* - muxing: set by avformat_write_header()
1365	* - demuxing: set by avformat_open_input()
1366	*/
1367	void *priv_data;
1368
1369	/**
1370	* I/O context.
1371	*
1372	* - demuxing: either set by the user before avformat_open_input() (then
1373	* the user must close it manually) or set by avformat_open_input().
1374	* - muxing: set by the user before avformat_write_header(). The caller must
1375	* take care of closing / freeing the IO context.
1376	*
1377	* Do NOT set this field if AVFMT_NOFILE flag is set in
1378	* iformat/oformat.flags. In such a case, the (de)muxer will handle
1379	* I/O in some other way and this field will be NULL.
1380	*/
1381	AVIOContext *pb;
1382
1383	/* stream info */
1384	/**
1385	* Flags signalling stream properties. A combination of AVFMTCTX_*.
1386	* Set by libavformat.
1387	*/
1388	int ctx_flags;
1389
1390	/**
1391	* Number of elements in AVFormatContext.streams.
1392	*
1393	* Set by avformat_new_stream(), must not be modified by any other code.
1394	*/
1395	unsigned int nb_streams;
1396	/**
1397	* A list of all streams in the file. New streams are created with
1398	* avformat_new_stream().
1399	*
1400	* - demuxing: streams are created by libavformat in avformat_open_input().
1401	* If AVFMTCTX_NOHEADER is set in ctx_flags, then new streams may also
1402	* appear in av_read_frame().
1403	* - muxing: streams are created by the user before avformat_write_header().
1404	*
1405	* Freed by libavformat in avformat_free_context().
1406	*/
1407	AVStream **streams;
1408
1409	/**
1410	* input or output filename
1411	*
1412	* - demuxing: set by avformat_open_input()
1413	* - muxing: may be set by the caller before avformat_write_header()
1414	*/
1415	char filename[1024];
1416
1417	/**
1418	* Position of the first frame of the component, in
1419	* AV_TIME_BASE fractional seconds. NEVER set this value directly:
1420	* It is deduced from the AVStream values.
1421	*
1422	* Demuxing only, set by libavformat.
1423	*/
1424	int64_t start_time;
1425
1426	/**
1427	* Duration of the stream, in AV_TIME_BASE fractional
1428	* seconds. Only set this value if you know none of the individual stream
1429	* durations and also do not set any of them. This is deduced from the
1430	* AVStream values if not set.
1431	*
1432	* Demuxing only, set by libavformat.
1433	*/
1434	int64_t duration;
1435
1436	/**
1437	* Total stream bitrate in bit/s, 0 if not
1438	* available. Never set it directly if the file_size and the
1439	* duration are known as FFmpeg can compute it automatically.
1440	*/
1441	int64_t bit_rate;
1442
1443	unsigned int packet_size;
1444	int max_delay;
1445
1446	/**
1447	* Flags modifying the (de)muxer behaviour. A combination of AVFMT_FLAG_*.
1448	* Set by the user before avformat_open_input() / avformat_write_header().
1449	*/
1450	int flags;
1451	#define AVFMT_FLAG_GENPTS 0x0001 ///< Generate missing pts even if it requires parsing future frames.
1452	#define AVFMT_FLAG_IGNIDX 0x0002 ///< Ignore index.
1453	#define AVFMT_FLAG_NONBLOCK 0x0004 ///< Do not block when reading packets from input.
1454	#define AVFMT_FLAG_IGNDTS 0x0008 ///< Ignore DTS on frames that contain both DTS & PTS
1455	#define AVFMT_FLAG_NOFILLIN 0x0010 ///< Do not infer any values from other values, just return what is stored in the container
1456	#define AVFMT_FLAG_NOPARSE 0x0020 ///< Do not use AVParsers, you also must set AVFMT_FLAG_NOFILLIN as the fillin code works on frames and no parsing -> no frames. Also seeking to frames can not work if parsing to find frame boundaries has been disabled
1457	#define AVFMT_FLAG_NOBUFFER 0x0040 ///< Do not buffer frames when possible
1458	#define AVFMT_FLAG_CUSTOM_IO 0x0080 ///< The caller has supplied a custom AVIOContext, don't avio_close() it.
1459	#define AVFMT_FLAG_DISCARD_CORRUPT 0x0100 ///< Discard frames marked corrupted
1460	#define AVFMT_FLAG_FLUSH_PACKETS 0x0200 ///< Flush the AVIOContext every packet.
1461	/**
1462	* When muxing, try to avoid writing any random/volatile data to the output.
1463	* This includes any random IDs, real-time timestamps/dates, muxer version, etc.
1464	*
1465	* This flag is mainly intended for testing.
1466	*/
1467	#define AVFMT_FLAG_BITEXACT 0x0400
1468	#define AVFMT_FLAG_MP4A_LATM 0x8000 ///< Enable RTP MP4A-LATM payload
1469	#define AVFMT_FLAG_SORT_DTS 0x10000 ///< try to interleave outputted packets by dts (using this flag can slow demuxing down)
1470	#define AVFMT_FLAG_PRIV_OPT 0x20000 ///< Enable use of private options by delaying codec open (this could be made default once all code is converted)
1471	#if FF_API_LAVF_KEEPSIDE_FLAG
1472	#define AVFMT_FLAG_KEEP_SIDE_DATA 0x40000 ///< Don't merge side data but keep it separate. Deprecated, will be the default.
1473	#endif
1474	#define AVFMT_FLAG_FAST_SEEK 0x80000 ///< Enable fast, but inaccurate seeks for some formats
1475	#define AVFMT_FLAG_SHORTEST 0x100000 ///< Stop muxing when the shortest stream stops.
1476	#define AVFMT_FLAG_AUTO_BSF 0x200000 ///< Wait for packet data before writing a header, and add bitstream filters as requested by the muxer
1477
1478	/**
1479	* Maximum size of the data read from input for determining
1480	* the input container format.
1481	* Demuxing only, set by the caller before avformat_open_input().
1482	*/
1483	int64_t probesize;
1484
1485	/**
1486	* Maximum duration (in AV_TIME_BASE units) of the data read
1487	* from input in avformat_find_stream_info().
1488	* Demuxing only, set by the caller before avformat_find_stream_info().
1489	* Can be set to 0 to let avformat choose using a heuristic.
1490	*/
1491	int64_t max_analyze_duration;
1492
1493	const uint8_t *key;
1494	int keylen;
1495
1496	unsigned int nb_programs;
1497	AVProgram **programs;
1498
1499	/**
1500	* Forced video codec_id.
1501	* Demuxing: Set by user.
1502	*/
1503	enum AVCodecID video_codec_id;
1504
1505	/**
1506	* Forced audio codec_id.
1507	* Demuxing: Set by user.
1508	*/
1509	enum AVCodecID audio_codec_id;
1510
1511	/**
1512	* Forced subtitle codec_id.
1513	* Demuxing: Set by user.
1514	*/
1515	enum AVCodecID subtitle_codec_id;
1516
1517	/**
1518	* Maximum amount of memory in bytes to use for the index of each stream.
1519	* If the index exceeds this size, entries will be discarded as
1520	* needed to maintain a smaller size. This can lead to slower or less
1521	* accurate seeking (depends on demuxer).
1522	* Demuxers for which a full in-memory index is mandatory will ignore
1523	* this.
1524	* - muxing: unused
1525	* - demuxing: set by user
1526	*/
1527	unsigned int max_index_size;
1528
1529	/**
1530	* Maximum amount of memory in bytes to use for buffering frames
1531	* obtained from realtime capture devices.
1532	*/
1533	unsigned int max_picture_buffer;
1534
1535	/**
1536	* Number of chapters in AVChapter array.
1537	* When muxing, chapters are normally written in the file header,
1538	* so nb_chapters should normally be initialized before write_header
1539	* is called. Some muxers (e.g. mov and mkv) can also write chapters
1540	* in the trailer. To write chapters in the trailer, nb_chapters
1541	* must be zero when write_header is called and non-zero when
1542	* write_trailer is called.
1543	* - muxing: set by user
1544	* - demuxing: set by libavformat
1545	*/
1546	unsigned int nb_chapters;
1547	AVChapter **chapters;
1548
1549	/**
1550	* Metadata that applies to the whole file.
1551	*
1552	* - demuxing: set by libavformat in avformat_open_input()
1553	* - muxing: may be set by the caller before avformat_write_header()
1554	*
1555	* Freed by libavformat in avformat_free_context().
1556	*/
1557	AVDictionary *metadata;
1558
1559	/**
1560	* Start time of the stream in real world time, in microseconds
1561	* since the Unix epoch (00:00 1st January 1970). That is, pts=0 in the
1562	* stream was captured at this real world time.
1563	* - muxing: Set by the caller before avformat_write_header(). If set to
1564	* either 0 or AV_NOPTS_VALUE, then the current wall-time will
1565	* be used.
1566	* - demuxing: Set by libavformat. AV_NOPTS_VALUE if unknown. Note that
1567	* the value may become known after some number of frames
1568	* have been received.
1569	*/
1570	int64_t start_time_realtime;
1571
1572	/**
1573	* The number of frames used for determining the framerate in
1574	* avformat_find_stream_info().
1575	* Demuxing only, set by the caller before avformat_find_stream_info().
1576	*/
1577	int fps_probe_size;
1578
1579	/**
1580	* Error recognition; higher values will detect more errors but may
1581	* misdetect some more or less valid parts as errors.
1582	* Demuxing only, set by the caller before avformat_open_input().
1583	*/
1584	int error_recognition;
1585
1586	/**
1587	* Custom interrupt callbacks for the I/O layer.
1588	*
1589	* demuxing: set by the user before avformat_open_input().
1590	* muxing: set by the user before avformat_write_header()
1591	* (mainly useful for AVFMT_NOFILE formats). The callback
1592	* should also be passed to avio_open2() if it's used to
1593	* open the file.
1594	*/
1595	AVIOInterruptCB interrupt_callback;
1596
1597	/**
1598	* Flags to enable debugging.
1599	*/
1600	int debug;
1601	#define FF_FDEBUG_TS 0x0001
1602
1603	/**
1604	* Maximum buffering duration for interleaving.
1605	*
1606	* To ensure all the streams are interleaved correctly,
1607	* av_interleaved_write_frame() will wait until it has at least one packet
1608	* for each stream before actually writing any packets to the output file.
1609	* When some streams are "sparse" (i.e. there are large gaps between
1610	* successive packets), this can result in excessive buffering.
1611	*
1612	* This field specifies the maximum difference between the timestamps of the
1613	* first and the last packet in the muxing queue, above which libavformat
1614	* will output a packet regardless of whether it has queued a packet for all
1615	* the streams.
1616	*
1617	* Muxing only, set by the caller before avformat_write_header().
1618	*/
1619	int64_t max_interleave_delta;
1620
1621	/**
1622	* Allow non-standard and experimental extension
1623	* @see AVCodecContext.strict_std_compliance
1624	*/
1625	int strict_std_compliance;
1626
1627	/**
1628	* Flags for the user to detect events happening on the file. Flags must
1629	* be cleared by the user once the event has been handled.
1630	* A combination of AVFMT_EVENT_FLAG_*.
1631	*/
1632	int event_flags;
1633	#define AVFMT_EVENT_FLAG_METADATA_UPDATED 0x0001 ///< The call resulted in updated metadata.
1634
1635	/**
1636	* Maximum number of packets to read while waiting for the first timestamp.
1637	* Decoding only.
1638	*/
1639	int max_ts_probe;
1640
1641	/**
1642	* Avoid negative timestamps during muxing.
1643	* Any value of the AVFMT_AVOID_NEG_TS_* constants.
1644	* Note, this only works when using av_interleaved_write_frame. (interleave_packet_per_dts is in use)
1645	* - muxing: Set by user
1646	* - demuxing: unused
1647	*/
1648	int avoid_negative_ts;
1649	#define AVFMT_AVOID_NEG_TS_AUTO -1 ///< Enabled when required by target format
1650	#define AVFMT_AVOID_NEG_TS_MAKE_NON_NEGATIVE 1 ///< Shift timestamps so they are non negative
1651	#define AVFMT_AVOID_NEG_TS_MAKE_ZERO 2 ///< Shift timestamps so that they start at 0
1652
1653	/**
1654	* Transport stream id.
1655	* This will be moved into demuxer private options. Thus no API/ABI compatibility
1656	*/
1657	int ts_id;
1658
1659	/**
1660	* Audio preload in microseconds.
1661	* Note, not all formats support this and unpredictable things may happen if it is used when not supported.
1662	* - encoding: Set by user
1663	* - decoding: unused
1664	*/
1665	int audio_preload;
1666
1667	/**
1668	* Max chunk time in microseconds.
1669	* Note, not all formats support this and unpredictable things may happen if it is used when not supported.
1670	* - encoding: Set by user
1671	* - decoding: unused
1672	*/
1673	int max_chunk_duration;
1674
1675	/**
1676	* Max chunk size in bytes
1677	* Note, not all formats support this and unpredictable things may happen if it is used when not supported.
1678	* - encoding: Set by user
1679	* - decoding: unused
1680	*/
1681	int max_chunk_size;
1682
1683	/**
1684	* forces the use of wallclock timestamps as pts/dts of packets
1685	* This has undefined results in the presence of B frames.
1686	* - encoding: unused
1687	* - decoding: Set by user
1688	*/
1689	int use_wallclock_as_timestamps;
1690
1691	/**
1692	* avio flags, used to force AVIO_FLAG_DIRECT.
1693	* - encoding: unused
1694	* - decoding: Set by user
1695	*/
1696	int avio_flags;
1697
1698	/**
1699	* The duration field can be estimated through various ways, and this field can be used
1700	* to know how the duration was estimated.
1701	* - encoding: unused
1702	* - decoding: Read by user
1703	*/
1704	enum AVDurationEstimationMethod duration_estimation_method;
1705
1706	/**
1707	* Skip initial bytes when opening stream
1708	* - encoding: unused
1709	* - decoding: Set by user
1710	*/
1711	int64_t skip_initial_bytes;
1712
1713	/**
1714	* Correct single timestamp overflows
1715	* - encoding: unused
1716	* - decoding: Set by user
1717	*/
1718	unsigned int correct_ts_overflow;
1719
1720	/**
1721	* Force seeking to any (also non key) frames.
1722	* - encoding: unused
1723	* - decoding: Set by user
1724	*/
1725	int seek2any;
1726
1727	/**
1728	* Flush the I/O context after each packet.
1729	* - encoding: Set by user
1730	* - decoding: unused
1731	*/
1732	int flush_packets;
1733
1734	/**
1735	* format probing score.
1736	* The maximal score is AVPROBE_SCORE_MAX, its set when the demuxer probes
1737	* the format.
1738	* - encoding: unused
1739	* - decoding: set by avformat, read by user
1740	*/
1741	int probe_score;
1742
1743	/**
1744	* number of bytes to read maximally to identify format.
1745	* - encoding: unused
1746	* - decoding: set by user
1747	*/
1748	int format_probesize;
1749
1750	/**
1751	* ',' separated list of allowed decoders.
1752	* If NULL then all are allowed
1753	* - encoding: unused
1754	* - decoding: set by user
1755	*/
1756	char *codec_whitelist;
1757
1758	/**
1759	* ',' separated list of allowed demuxers.
1760	* If NULL then all are allowed
1761	* - encoding: unused
1762	* - decoding: set by user
1763	*/
1764	char *format_whitelist;
1765
1766	/**
1767	* An opaque field for libavformat internal usage.
1768	* Must not be accessed in any way by callers.
1769	*/
1770	AVFormatInternal *internal;
1771
1772	/**
1773	* IO repositioned flag.
1774	* This is set by avformat when the underlaying IO context read pointer
1775	* is repositioned, for example when doing byte based seeking.
1776	* Demuxers can use the flag to detect such changes.
1777	*/
1778	int io_repositioned;
1779
1780	/**
1781	* Forced video codec.
1782	* This allows forcing a specific decoder, even when there are multiple with
1783	* the same codec_id.
1784	* Demuxing: Set by user
1785	*/
1786	AVCodec *video_codec;
1787
1788	/**
1789	* Forced audio codec.
1790	* This allows forcing a specific decoder, even when there are multiple with
1791	* the same codec_id.
1792	* Demuxing: Set by user
1793	*/
1794	AVCodec *audio_codec;
1795
1796	/**
1797	* Forced subtitle codec.
1798	* This allows forcing a specific decoder, even when there are multiple with
1799	* the same codec_id.
1800	* Demuxing: Set by user
1801	*/
1802	AVCodec *subtitle_codec;
1803
1804	/**
1805	* Forced data codec.
1806	* This allows forcing a specific decoder, even when there are multiple with
1807	* the same codec_id.
1808	* Demuxing: Set by user
1809	*/
1810	AVCodec *data_codec;
1811
1812	/**
1813	* Number of bytes to be written as padding in a metadata header.
1814	* Demuxing: Unused.
1815	* Muxing: Set by user via av_format_set_metadata_header_padding.
1816	*/
1817	int metadata_header_padding;
1818
1819	/**
1820	* User data.
1821	* This is a place for some private data of the user.
1822	*/
1823	void *opaque;
1824
1825	/**
1826	* Callback used by devices to communicate with application.
1827	*/
1828	av_format_control_message control_message_cb;
1829
1830	/**
1831	* Output timestamp offset, in microseconds.
1832	* Muxing: set by user
1833	*/
1834	int64_t output_ts_offset;
1835
1836	/**
1837	* dump format separator.
1838	* can be ", " or "\n " or anything else
1839	* - muxing: Set by user.
1840	* - demuxing: Set by user.
1841	*/
1842	uint8_t *dump_separator;
1843
1844	/**
1845	* Forced Data codec_id.
1846	* Demuxing: Set by user.
1847	*/
1848	enum AVCodecID data_codec_id;
1849
1850	#if FF_API_OLD_OPEN_CALLBACKS
1851	/**
1852	* Called to open further IO contexts when needed for demuxing.
1853	*
1854	* This can be set by the user application to perform security checks on
1855	* the URLs before opening them.
1856	* The function should behave like avio_open2(), AVFormatContext is provided
1857	* as contextual information and to reach AVFormatContext.opaque.
1858	*
1859	* If NULL then some simple checks are used together with avio_open2().
1860	*
1861	* Must not be accessed directly from outside avformat.
1862	* @See av_format_set_open_cb()
1863	*
1864	* Demuxing: Set by user.
1865	*
1866	* @deprecated Use io_open and io_close.
1867	*/
1868	attribute_deprecated
1869	int (*open_cb)(struct AVFormatContext *s, AVIOContext **p, const char *url, int flags, const AVIOInterruptCB *int_cb, AVDictionary **options);
1870	#endif
1871
1872	/**
1873	* ',' separated list of allowed protocols.
1874	* - encoding: unused
1875	* - decoding: set by user
1876	*/
1877	char *protocol_whitelist;
1878
1879	/*
1880	* A callback for opening new IO streams.
1881	*
1882	* Whenever a muxer or a demuxer needs to open an IO stream (typically from
1883	* avformat_open_input() for demuxers, but for certain formats can happen at
1884	* other times as well), it will call this callback to obtain an IO context.
1885	*
1886	* @param s the format context
1887	* @param pb on success, the newly opened IO context should be returned here
1888	* @param url the url to open
1889	* @param flags a combination of AVIO_FLAG_*
1890	* @param options a dictionary of additional options, with the same
1891	* semantics as in avio_open2()
1892	* @return 0 on success, a negative AVERROR code on failure
1893	*
1894	* @note Certain muxers and demuxers do nesting, i.e. they open one or more
1895	* additional internal format contexts. Thus the AVFormatContext pointer
1896	* passed to this callback may be different from the one facing the caller.
1897	* It will, however, have the same 'opaque' field.
1898	*/
1899	int (*io_open)(struct AVFormatContext *s, AVIOContext **pb, const char *url,
1900	int flags, AVDictionary **options);
1901
1902	/**
1903	* A callback for closing the streams opened with AVFormatContext.io_open().
1904	*/
1905	void (*io_close)(struct AVFormatContext *s, AVIOContext *pb);
1906
1907	/**
1908	* ',' separated list of disallowed protocols.
1909	* - encoding: unused
1910	* - decoding: set by user
1911	*/
1912	char *protocol_blacklist;
1913
1914	/**
1915	* The maximum number of streams.
1916	* - encoding: unused
1917	* - decoding: set by user
1918	*/
1919	int max_streams;
1920	} AVFormatContext;
1921
1922	/**
1923	* Accessors for some AVFormatContext fields. These used to be provided for ABI
1924	* compatibility, and do not need to be used anymore.
1925	*/
1926	int av_format_get_probe_score(const AVFormatContext *s);
1927	AVCodec * av_format_get_video_codec(const AVFormatContext *s);
1928	void av_format_set_video_codec(AVFormatContext *s, AVCodec *c);
1929	AVCodec * av_format_get_audio_codec(const AVFormatContext *s);
1930	void av_format_set_audio_codec(AVFormatContext *s, AVCodec *c);
1931	AVCodec * av_format_get_subtitle_codec(const AVFormatContext *s);
1932	void av_format_set_subtitle_codec(AVFormatContext *s, AVCodec *c);
1933	AVCodec * av_format_get_data_codec(const AVFormatContext *s);
1934	void av_format_set_data_codec(AVFormatContext *s, AVCodec *c);
1935	int av_format_get_metadata_header_padding(const AVFormatContext *s);
1936	void av_format_set_metadata_header_padding(AVFormatContext *s, int c);
1937	void * av_format_get_opaque(const AVFormatContext *s);
1938	void av_format_set_opaque(AVFormatContext *s, void *opaque);
1939	av_format_control_message av_format_get_control_message_cb(const AVFormatContext *s);
1940	void av_format_set_control_message_cb(AVFormatContext *s, av_format_control_message callback);
1941	#if FF_API_OLD_OPEN_CALLBACKS
1942	attribute_deprecated AVOpenCallback av_format_get_open_cb(const AVFormatContext *s);
1943	attribute_deprecated void av_format_set_open_cb(AVFormatContext *s, AVOpenCallback callback);
1944	#endif
1945
1946	/**
1947	* This function will cause global side data to be injected in the next packet
1948	* of each stream as well as after any subsequent seek.
1949	*/
1950	void av_format_inject_global_side_data(AVFormatContext *s);
1951
1952	/**
1953	* Returns the method used to set ctx->duration.
1954	*
1955	* @return AVFMT_DURATION_FROM_PTS, AVFMT_DURATION_FROM_STREAM, or AVFMT_DURATION_FROM_BITRATE.
1956	*/
1957	enum AVDurationEstimationMethod av_fmt_ctx_get_duration_estimation_method(const AVFormatContext* ctx);
1958
1959	typedef struct AVPacketList {
1960	AVPacket pkt;
1961	struct AVPacketList *next;
1962	} AVPacketList;
1963
1964
1965	/**
1966	* @defgroup lavf_core Core functions
1967	* @ingroup libavf
1968	*
1969	* Functions for querying libavformat capabilities, allocating core structures,
1970	* etc.
1971	* @{
1972	*/
1973
1974	/**
1975	* Return the LIBAVFORMAT_VERSION_INT constant.
1976	*/
1977	unsigned avformat_version(void);
1978
1979	/**
1980	* Return the libavformat build-time configuration.
1981	*/
1982	const char *avformat_configuration(void);
1983
1984	/**
1985	* Return the libavformat license.
1986	*/
1987	const char *avformat_license(void);
1988
1989	/**
1990	* Initialize libavformat and register all the muxers, demuxers and
1991	* protocols. If you do not call this function, then you can select
1992	* exactly which formats you want to support.
1993	*
1994	* @see av_register_input_format()
1995	* @see av_register_output_format()
1996	*/
1997	void av_register_all(void);
1998
1999	void av_register_input_format(AVInputFormat *format);
2000	void av_register_output_format(AVOutputFormat *format);
2001
2002	/**
2003	* Do global initialization of network components. This is optional,
2004	* but recommended, since it avoids the overhead of implicitly
2005	* doing the setup for each session.
2006	*
2007	* Calling this function will become mandatory if using network
2008	* protocols at some major version bump.
2009	*/
2010	int avformat_network_init(void);
2011
2012	/**
2013	* Undo the initialization done by avformat_network_init.
2014	*/
2015	int avformat_network_deinit(void);
2016
2017	/**
2018	* If f is NULL, returns the first registered input format,
2019	* if f is non-NULL, returns the next registered input format after f
2020	* or NULL if f is the last one.
2021	*/
2022	AVInputFormat *av_iformat_next(const AVInputFormat *f);
2023
2024	/**
2025	* If f is NULL, returns the first registered output format,
2026	* if f is non-NULL, returns the next registered output format after f
2027	* or NULL if f is the last one.
2028	*/
2029	AVOutputFormat *av_oformat_next(const AVOutputFormat *f);
2030
2031	/**
2032	* Allocate an AVFormatContext.
2033	* avformat_free_context() can be used to free the context and everything
2034	* allocated by the framework within it.
2035	*/
2036	AVFormatContext *avformat_alloc_context(void);
2037
2038	/**
2039	* Free an AVFormatContext and all its streams.
2040	* @param s context to free
2041	*/
2042	void avformat_free_context(AVFormatContext *s);
2043
2044	/**
2045	* Get the AVClass for AVFormatContext. It can be used in combination with
2046	* AV_OPT_SEARCH_FAKE_OBJ for examining options.
2047	*
2048	* @see av_opt_find().
2049	*/
2050	const AVClass *avformat_get_class(void);
2051
2052	/**
2053	* Add a new stream to a media file.
2054	*
2055	* When demuxing, it is called by the demuxer in read_header(). If the
2056	* flag AVFMTCTX_NOHEADER is set in s.ctx_flags, then it may also
2057	* be called in read_packet().
2058	*
2059	* When muxing, should be called by the user before avformat_write_header().
2060	*
2061	* User is required to call avcodec_close() and avformat_free_context() to
2062	* clean up the allocation by avformat_new_stream().
2063	*
2064	* @param s media file handle
2065	* @param c If non-NULL, the AVCodecContext corresponding to the new stream
2066	* will be initialized to use this codec. This is needed for e.g. codec-specific
2067	* defaults to be set, so codec should be provided if it is known.
2068	*
2069	* @return newly created stream or NULL on error.
2070	*/
2071	AVStream *avformat_new_stream(AVFormatContext *s, const AVCodec *c);
2072
2073	/**
2074	* Wrap an existing array as stream side data.
2075	*
2076	* @param st stream
2077	* @param type side information type
2078	* @param data the side data array. It must be allocated with the av_malloc()
2079	* family of functions. The ownership of the data is transferred to
2080	* st.
2081	* @param size side information size
2082	* @return zero on success, a negative AVERROR code on failure. On failure,
2083	* the stream is unchanged and the data remains owned by the caller.
2084	*/
2085	int av_stream_add_side_data(AVStream *st, enum AVPacketSideDataType type,
2086	uint8_t *data, size_t size);
2087
2088	/**
2089	* Allocate new information from stream.
2090	*
2091	* @param stream stream
2092	* @param type desired side information type
2093	* @param size side information size
2094	* @return pointer to fresh allocated data or NULL otherwise
2095	*/
2096	uint8_t *av_stream_new_side_data(AVStream *stream,
2097	enum AVPacketSideDataType type, int size);
2098	/**
2099	* Get side information from stream.
2100	*
2101	* @param stream stream
2102	* @param type desired side information type
2103	* @param size pointer for side information size to store (optional)
2104	* @return pointer to data if present or NULL otherwise
2105	*/
2106	#if FF_API_NOCONST_GET_SIDE_DATA
2107	uint8_t *av_stream_get_side_data(AVStream *stream,
2108	enum AVPacketSideDataType type, int *size);
2109	#else
2110	uint8_t *av_stream_get_side_data(const AVStream *stream,
2111	enum AVPacketSideDataType type, int *size);
2112	#endif
2113
2114	AVProgram *av_new_program(AVFormatContext *s, int id);
2115
2116	/**
2117	* @}
2118	*/
2119
2120
2121	/**
2122	* Allocate an AVFormatContext for an output format.
2123	* avformat_free_context() can be used to free the context and
2124	* everything allocated by the framework within it.
2125	*
2126	* @param *ctx is set to the created format context, or to NULL in
2127	* case of failure
2128	* @param oformat format to use for allocating the context, if NULL
2129	* format_name and filename are used instead
2130	* @param format_name the name of output format to use for allocating the
2131	* context, if NULL filename is used instead
2132	* @param filename the name of the filename to use for allocating the
2133	* context, may be NULL
2134	* @return >= 0 in case of success, a negative AVERROR code in case of
2135	* failure
2136	*/
2137	int avformat_alloc_output_context2(AVFormatContext **ctx, AVOutputFormat *oformat,
2138	const char *format_name, const char *filename);
2139
2140	/**
2141	* @addtogroup lavf_decoding
2142	* @{
2143	*/
2144
2145	/**
2146	* Find AVInputFormat based on the short name of the input format.
2147	*/
2148	AVInputFormat *av_find_input_format(const char *short_name);
2149
2150	/**
2151	* Guess the file format.
2152	*
2153	* @param pd data to be probed
2154	* @param is_opened Whether the file is already opened; determines whether
2155	* demuxers with or without AVFMT_NOFILE are probed.
2156	*/
2157	AVInputFormat *av_probe_input_format(AVProbeData *pd, int is_opened);
2158
2159	/**
2160	* Guess the file format.
2161	*
2162	* @param pd data to be probed
2163	* @param is_opened Whether the file is already opened; determines whether
2164	* demuxers with or without AVFMT_NOFILE are probed.
2165	* @param score_max A probe score larger that this is required to accept a
2166	* detection, the variable is set to the actual detection
2167	* score afterwards.
2168	* If the score is <= AVPROBE_SCORE_MAX / 4 it is recommended
2169	* to retry with a larger probe buffer.
2170	*/
2171	AVInputFormat *av_probe_input_format2(AVProbeData *pd, int is_opened, int *score_max);
2172
2173	/**
2174	* Guess the file format.
2175	*
2176	* @param is_opened Whether the file is already opened; determines whether
2177	* demuxers with or without AVFMT_NOFILE are probed.
2178	* @param score_ret The score of the best detection.
2179	*/
2180	AVInputFormat *av_probe_input_format3(AVProbeData *pd, int is_opened, int *score_ret);
2181
2182	/**
2183	* Probe a bytestream to determine the input format. Each time a probe returns
2184	* with a score that is too low, the probe buffer size is increased and another
2185	* attempt is made. When the maximum probe size is reached, the input format
2186	* with the highest score is returned.
2187	*
2188	* @param pb the bytestream to probe
2189	* @param fmt the input format is put here
2190	* @param url the url of the stream
2191	* @param logctx the log context
2192	* @param offset the offset within the bytestream to probe from
2193	* @param max_probe_size the maximum probe buffer size (zero for default)
2194	* @return the score in case of success, a negative value corresponding to an
2195	* the maximal score is AVPROBE_SCORE_MAX
2196	* AVERROR code otherwise
2197	*/
2198	int av_probe_input_buffer2(AVIOContext *pb, AVInputFormat **fmt,
2199	const char *url, void *logctx,
2200	unsigned int offset, unsigned int max_probe_size);
2201
2202	/**
2203	* Like av_probe_input_buffer2() but returns 0 on success
2204	*/
2205	int av_probe_input_buffer(AVIOContext *pb, AVInputFormat **fmt,
2206	const char *url, void *logctx,
2207	unsigned int offset, unsigned int max_probe_size);
2208
2209	/**
2210	* Open an input stream and read the header. The codecs are not opened.
2211	* The stream must be closed with avformat_close_input().
2212	*
2213	* @param ps Pointer to user-supplied AVFormatContext (allocated by avformat_alloc_context).
2214	* May be a pointer to NULL, in which case an AVFormatContext is allocated by this
2215	* function and written into ps.
2216	* Note that a user-supplied AVFormatContext will be freed on failure.
2217	* @param url URL of the stream to open.
2218	* @param fmt If non-NULL, this parameter forces a specific input format.
2219	* Otherwise the format is autodetected.
2220	* @param options A dictionary filled with AVFormatContext and demuxer-private options.
2221	* On return this parameter will be destroyed and replaced with a dict containing
2222	* options that were not found. May be NULL.
2223	*
2224	* @return 0 on success, a negative AVERROR on failure.
2225	*
2226	* @note If you want to use custom IO, preallocate the format context and set its pb field.
2227	*/
2228	int avformat_open_input(AVFormatContext **ps, const char *url, AVInputFormat *fmt, AVDictionary **options);
2229
2230	attribute_deprecated
2231	int av_demuxer_open(AVFormatContext *ic);
2232
2233	/**
2234	* Read packets of a media file to get stream information. This
2235	* is useful for file formats with no headers such as MPEG. This
2236	* function also computes the real framerate in case of MPEG-2 repeat
2237	* frame mode.
2238	* The logical file position is not changed by this function;
2239	* examined packets may be buffered for later processing.
2240	*
2241	* @param ic media file handle
2242	* @param options If non-NULL, an ic.nb_streams long array of pointers to
2243	* dictionaries, where i-th member contains options for
2244	* codec corresponding to i-th stream.
2245	* On return each dictionary will be filled with options that were not found.
2246	* @return >=0 if OK, AVERROR_xxx on error
2247	*
2248	* @note this function isn't guaranteed to open all the codecs, so
2249	* options being non-empty at return is a perfectly normal behavior.
2250	*
2251	* @todo Let the user decide somehow what information is needed so that
2252	* we do not waste time getting stuff the user does not need.
2253	*/
2254	int avformat_find_stream_info(AVFormatContext *ic, AVDictionary **options);
2255
2256	/**
2257	* Find the programs which belong to a given stream.
2258	*
2259	* @param ic media file handle
2260	* @param last the last found program, the search will start after this
2261	* program, or from the beginning if it is NULL
2262	* @param s stream index
2263	* @return the next program which belongs to s, NULL if no program is found or
2264	* the last program is not among the programs of ic.
2265	*/
2266	AVProgram *av_find_program_from_stream(AVFormatContext *ic, AVProgram *last, int s);
2267
2268	void av_program_add_stream_index(AVFormatContext *ac, int progid, unsigned int idx);
2269
2270	/**
2271	* Find the "best" stream in the file.
2272	* The best stream is determined according to various heuristics as the most
2273	* likely to be what the user expects.
2274	* If the decoder parameter is non-NULL, av_find_best_stream will find the
2275	* default decoder for the stream's codec; streams for which no decoder can
2276	* be found are ignored.
2277	*
2278	* @param ic media file handle
2279	* @param type stream type: video, audio, subtitles, etc.
2280	* @param wanted_stream_nb user-requested stream number,
2281	* or -1 for automatic selection
2282	* @param related_stream try to find a stream related (eg. in the same
2283	* program) to this one, or -1 if none
2284	* @param decoder_ret if non-NULL, returns the decoder for the
2285	* selected stream
2286	* @param flags flags; none are currently defined
2287	* @return the non-negative stream number in case of success,
2288	* AVERROR_STREAM_NOT_FOUND if no stream with the requested type
2289	* could be found,
2290	* AVERROR_DECODER_NOT_FOUND if streams were found but no decoder
2291	* @note If av_find_best_stream returns successfully and decoder_ret is not
2292	* NULL, then *decoder_ret is guaranteed to be set to a valid AVCodec.
2293	*/
2294	int av_find_best_stream(AVFormatContext *ic,
2295	enum AVMediaType type,
2296	int wanted_stream_nb,
2297	int related_stream,
2298	AVCodec **decoder_ret,
2299	int flags);
2300
2301	/**
2302	* Return the next frame of a stream.
2303	* This function returns what is stored in the file, and does not validate
2304	* that what is there are valid frames for the decoder. It will split what is
2305	* stored in the file into frames and return one for each call. It will not
2306	* omit invalid data between valid frames so as to give the decoder the maximum
2307	* information possible for decoding.
2308	*
2309	* If pkt->buf is NULL, then the packet is valid until the next
2310	* av_read_frame() or until avformat_close_input(). Otherwise the packet
2311	* is valid indefinitely. In both cases the packet must be freed with
2312	* av_packet_unref when it is no longer needed. For video, the packet contains
2313	* exactly one frame. For audio, it contains an integer number of frames if each
2314	* frame has a known fixed size (e.g. PCM or ADPCM data). If the audio frames
2315	* have a variable size (e.g. MPEG audio), then it contains one frame.
2316	*
2317	* pkt->pts, pkt->dts and pkt->duration are always set to correct
2318	* values in AVStream.time_base units (and guessed if the format cannot
2319	* provide them). pkt->pts can be AV_NOPTS_VALUE if the video format
2320	* has B-frames, so it is better to rely on pkt->dts if you do not
2321	* decompress the payload.
2322	*
2323	* @return 0 if OK, < 0 on error or end of file
2324	*/
2325	int av_read_frame(AVFormatContext *s, AVPacket *pkt);
2326
2327	/**
2328	* Seek to the keyframe at timestamp.
2329	* 'timestamp' in 'stream_index'.
2330	*
2331	* @param s media file handle
2332	* @param stream_index If stream_index is (-1), a default
2333	* stream is selected, and timestamp is automatically converted
2334	* from AV_TIME_BASE units to the stream specific time_base.
2335	* @param timestamp Timestamp in AVStream.time_base units
2336	* or, if no stream is specified, in AV_TIME_BASE units.
2337	* @param flags flags which select direction and seeking mode
2338	* @return >= 0 on success
2339	*/
2340	int av_seek_frame(AVFormatContext *s, int stream_index, int64_t timestamp,
2341	int flags);
2342
2343	/**
2344	* Seek to timestamp ts.
2345	* Seeking will be done so that the point from which all active streams
2346	* can be presented successfully will be closest to ts and within min/max_ts.
2347	* Active streams are all streams that have AVStream.discard < AVDISCARD_ALL.
2348	*
2349	* If flags contain AVSEEK_FLAG_BYTE, then all timestamps are in bytes and
2350	* are the file position (this may not be supported by all demuxers).
2351	* If flags contain AVSEEK_FLAG_FRAME, then all timestamps are in frames
2352	* in the stream with stream_index (this may not be supported by all demuxers).
2353	* Otherwise all timestamps are in units of the stream selected by stream_index
2354	* or if stream_index is -1, in AV_TIME_BASE units.
2355	* If flags contain AVSEEK_FLAG_ANY, then non-keyframes are treated as
2356	* keyframes (this may not be supported by all demuxers).
2357	* If flags contain AVSEEK_FLAG_BACKWARD, it is ignored.
2358	*
2359	* @param s media file handle
2360	* @param stream_index index of the stream which is used as time base reference
2361	* @param min_ts smallest acceptable timestamp
2362	* @param ts target timestamp
2363	* @param max_ts largest acceptable timestamp
2364	* @param flags flags
2365	* @return >=0 on success, error code otherwise
2366	*
2367	* @note This is part of the new seek API which is still under construction.
2368	* Thus do not use this yet. It may change at any time, do not expect
2369	* ABI compatibility yet!
2370	*/
2371	int avformat_seek_file(AVFormatContext *s, int stream_index, int64_t min_ts, int64_t ts, int64_t max_ts, int flags);
2372
2373	/**
2374	* Discard all internally buffered data. This can be useful when dealing with
2375	* discontinuities in the byte stream. Generally works only with formats that
2376	* can resync. This includes headerless formats like MPEG-TS/TS but should also
2377	* work with NUT, Ogg and in a limited way AVI for example.
2378	*
2379	* The set of streams, the detected duration, stream parameters and codecs do
2380	* not change when calling this function. If you want a complete reset, it's
2381	* better to open a new AVFormatContext.
2382	*
2383	* This does not flush the AVIOContext (s->pb). If necessary, call
2384	* avio_flush(s->pb) before calling this function.
2385	*
2386	* @param s media file handle
2387	* @return >=0 on success, error code otherwise
2388	*/
2389	int avformat_flush(AVFormatContext *s);
2390
2391	/**
2392	* Start playing a network-based stream (e.g. RTSP stream) at the
2393	* current position.
2394	*/
2395	int av_read_play(AVFormatContext *s);
2396
2397	/**
2398	* Pause a network-based stream (e.g. RTSP stream).
2399	*
2400	* Use av_read_play() to resume it.
2401	*/
2402	int av_read_pause(AVFormatContext *s);
2403
2404	/**
2405	* Close an opened input AVFormatContext. Free it and all its contents
2406	* and set *s to NULL.
2407	*/
2408	void avformat_close_input(AVFormatContext **s);
2409	/**
2410	* @}
2411	*/
2412
2413	#define AVSEEK_FLAG_BACKWARD 1 ///< seek backward
2414	#define AVSEEK_FLAG_BYTE 2 ///< seeking based on position in bytes
2415	#define AVSEEK_FLAG_ANY 4 ///< seek to any frame, even non-keyframes
2416	#define AVSEEK_FLAG_FRAME 8 ///< seeking based on frame number
2417
2418	/**
2419	* @addtogroup lavf_encoding
2420	* @{
2421	*/
2422
2423	#define AVSTREAM_INIT_IN_WRITE_HEADER 0 ///< stream parameters initialized in avformat_write_header
2424	#define AVSTREAM_INIT_IN_INIT_OUTPUT 1 ///< stream parameters initialized in avformat_init_output
2425
2426	/**
2427	* Allocate the stream private data and write the stream header to
2428	* an output media file.
2429	*
2430	* @param s Media file handle, must be allocated with avformat_alloc_context().
2431	* Its oformat field must be set to the desired output format;
2432	* Its pb field must be set to an already opened AVIOContext.
2433	* @param options An AVDictionary filled with AVFormatContext and muxer-private options.
2434	* On return this parameter will be destroyed and replaced with a dict containing
2435	* options that were not found. May be NULL.
2436	*
2437	* @return AVSTREAM_INIT_IN_WRITE_HEADER on success if the codec had not already been fully initialized in avformat_init,
2438	* AVSTREAM_INIT_IN_INIT_OUTPUT on success if the codec had already been fully initialized in avformat_init,
2439	* negative AVERROR on failure.
2440	*
2441	* @see av_opt_find, av_dict_set, avio_open, av_oformat_next, avformat_init_output.
2442	*/
2443	av_warn_unused_result
2444	int avformat_write_header(AVFormatContext *s, AVDictionary **options);
2445
2446	/**
2447	* Allocate the stream private data and initialize the codec, but do not write the header.
2448	* May optionally be used before avformat_write_header to initialize stream parameters
2449	* before actually writing the header.
2450	* If using this function, do not pass the same options to avformat_write_header.
2451	*
2452	* @param s Media file handle, must be allocated with avformat_alloc_context().
2453	* Its oformat field must be set to the desired output format;
2454	* Its pb field must be set to an already opened AVIOContext.
2455	* @param options An AVDictionary filled with AVFormatContext and muxer-private options.
2456	* On return this parameter will be destroyed and replaced with a dict containing
2457	* options that were not found. May be NULL.
2458	*
2459	* @return AVSTREAM_INIT_IN_WRITE_HEADER on success if the codec requires avformat_write_header to fully initialize,
2460	* AVSTREAM_INIT_IN_INIT_OUTPUT on success if the codec has been fully initialized,
2461	* negative AVERROR on failure.
2462	*
2463	* @see av_opt_find, av_dict_set, avio_open, av_oformat_next, avformat_write_header.
2464	*/
2465	av_warn_unused_result
2466	int avformat_init_output(AVFormatContext *s, AVDictionary **options);
2467
2468	/**
2469	* Write a packet to an output media file.
2470	*
2471	* This function passes the packet directly to the muxer, without any buffering
2472	* or reordering. The caller is responsible for correctly interleaving the
2473	* packets if the format requires it. Callers that want libavformat to handle
2474	* the interleaving should call av_interleaved_write_frame() instead of this
2475	* function.
2476	*
2477	* @param s media file handle
2478	* @param pkt The packet containing the data to be written. Note that unlike
2479	* av_interleaved_write_frame(), this function does not take
2480	* ownership of the packet passed to it (though some muxers may make
2481	* an internal reference to the input packet).
2482	* <br>
2483	* This parameter can be NULL (at any time, not just at the end), in
2484	* order to immediately flush data buffered within the muxer, for
2485	* muxers that buffer up data internally before writing it to the
2486	* output.
2487	* <br>
2488	* Packet's @ref AVPacket.stream_index "stream_index" field must be
2489	* set to the index of the corresponding stream in @ref
2490	* AVFormatContext.streams "s->streams".
2491	* <br>
2492	* The timestamps (@ref AVPacket.pts "pts", @ref AVPacket.dts "dts")
2493	* must be set to correct values in the stream's timebase (unless the
2494	* output format is flagged with the AVFMT_NOTIMESTAMPS flag, then
2495	* they can be set to AV_NOPTS_VALUE).
2496	* The dts for subsequent packets passed to this function must be strictly
2497	* increasing when compared in their respective timebases (unless the
2498	* output format is flagged with the AVFMT_TS_NONSTRICT, then they
2499	* merely have to be nondecreasing). @ref AVPacket.duration
2500	* "duration") should also be set if known.
2501	* @return < 0 on error, = 0 if OK, 1 if flushed and there is no more data to flush
2502	*
2503	* @see av_interleaved_write_frame()
2504	*/
2505	int av_write_frame(AVFormatContext *s, AVPacket *pkt);
2506
2507	/**
2508	* Write a packet to an output media file ensuring correct interleaving.
2509	*
2510	* This function will buffer the packets internally as needed to make sure the
2511	* packets in the output file are properly interleaved in the order of
2512	* increasing dts. Callers doing their own interleaving should call
2513	* av_write_frame() instead of this function.
2514	*
2515	* Using this function instead of av_write_frame() can give muxers advance
2516	* knowledge of future packets, improving e.g. the behaviour of the mp4
2517	* muxer for VFR content in fragmenting mode.
2518	*
2519	* @param s media file handle
2520	* @param pkt The packet containing the data to be written.
2521	* <br>
2522	* If the packet is reference-counted, this function will take
2523	* ownership of this reference and unreference it later when it sees
2524	* fit.
2525	* The caller must not access the data through this reference after
2526	* this function returns. If the packet is not reference-counted,
2527	* libavformat will make a copy.
2528	* <br>
2529	* This parameter can be NULL (at any time, not just at the end), to
2530	* flush the interleaving queues.
2531	* <br>
2532	* Packet's @ref AVPacket.stream_index "stream_index" field must be
2533	* set to the index of the corresponding stream in @ref
2534	* AVFormatContext.streams "s->streams".
2535	* <br>
2536	* The timestamps (@ref AVPacket.pts "pts", @ref AVPacket.dts "dts")
2537	* must be set to correct values in the stream's timebase (unless the
2538	* output format is flagged with the AVFMT_NOTIMESTAMPS flag, then
2539	* they can be set to AV_NOPTS_VALUE).
2540	* The dts for subsequent packets in one stream must be strictly
2541	* increasing (unless the output format is flagged with the
2542	* AVFMT_TS_NONSTRICT, then they merely have to be nondecreasing).
2543	* @ref AVPacket.duration "duration") should also be set if known.
2544	*
2545	* @return 0 on success, a negative AVERROR on error. Libavformat will always
2546	* take care of freeing the packet, even if this function fails.
2547	*
2548	* @see av_write_frame(), AVFormatContext.max_interleave_delta
2549	*/
2550	int av_interleaved_write_frame(AVFormatContext *s, AVPacket *pkt);
2551
2552	/**
2553	* Write an uncoded frame to an output media file.
2554	*
2555	* The frame must be correctly interleaved according to the container
2556	* specification; if not, then av_interleaved_write_frame() must be used.
2557	*
2558	* See av_interleaved_write_frame() for details.
2559	*/
2560	int av_write_uncoded_frame(AVFormatContext *s, int stream_index,
2561	AVFrame *frame);
2562
2563	/**
2564	* Write an uncoded frame to an output media file.
2565	*
2566	* If the muxer supports it, this function makes it possible to write an AVFrame
2567	* structure directly, without encoding it into a packet.
2568	* It is mostly useful for devices and similar special muxers that use raw
2569	* video or PCM data and will not serialize it into a byte stream.
2570	*
2571	* To test whether it is possible to use it with a given muxer and stream,
2572	* use av_write_uncoded_frame_query().
2573	*
2574	* The caller gives up ownership of the frame and must not access it
2575	* afterwards.
2576	*
2577	* @return >=0 for success, a negative code on error
2578	*/
2579	int av_interleaved_write_uncoded_frame(AVFormatContext *s, int stream_index,
2580	AVFrame *frame);
2581
2582	/**
2583	* Test whether a muxer supports uncoded frame.
2584	*
2585	* @return >=0 if an uncoded frame can be written to that muxer and stream,
2586	* <0 if not
2587	*/
2588	int av_write_uncoded_frame_query(AVFormatContext *s, int stream_index);
2589
2590	/**
2591	* Write the stream trailer to an output media file and free the
2592	* file private data.
2593	*
2594	* May only be called after a successful call to avformat_write_header.
2595	*
2596	* @param s media file handle
2597	* @return 0 if OK, AVERROR_xxx on error
2598	*/
2599	int av_write_trailer(AVFormatContext *s);
2600
2601	/**
2602	* Return the output format in the list of registered output formats
2603	* which best matches the provided parameters, or return NULL if
2604	* there is no match.
2605	*
2606	* @param short_name if non-NULL checks if short_name matches with the
2607	* names of the registered formats
2608	* @param filename if non-NULL checks if filename terminates with the
2609	* extensions of the registered formats
2610	* @param mime_type if non-NULL checks if mime_type matches with the
2611	* MIME type of the registered formats
2612	*/
2613	AVOutputFormat *av_guess_format(const char *short_name,
2614	const char *filename,
2615	const char *mime_type);
2616
2617	/**
2618	* Guess the codec ID based upon muxer and filename.
2619	*/
2620	enum AVCodecID av_guess_codec(AVOutputFormat *fmt, const char *short_name,
2621	const char *filename, const char *mime_type,
2622	enum AVMediaType type);
2623
2624	/**
2625	* Get timing information for the data currently output.
2626	* The exact meaning of "currently output" depends on the format.
2627	* It is mostly relevant for devices that have an internal buffer and/or
2628	* work in real time.
2629	* @param s media file handle
2630	* @param stream stream in the media file
2631	* @param[out] dts DTS of the last packet output for the stream, in stream
2632	* time_base units
2633	* @param[out] wall absolute time when that packet whas output,
2634	* in microsecond
2635	* @return 0 if OK, AVERROR(ENOSYS) if the format does not support it
2636	* Note: some formats or devices may not allow to measure dts and wall
2637	* atomically.
2638	*/
2639	int av_get_output_timestamp(struct AVFormatContext *s, int stream,
2640	int64_t *dts, int64_t *wall);
2641
2642
2643	/**
2644	* @}
2645	*/
2646
2647
2648	/**
2649	* @defgroup lavf_misc Utility functions
2650	* @ingroup libavf
2651	* @{
2652	*
2653	* Miscellaneous utility functions related to both muxing and demuxing
2654	* (or neither).
2655	*/
2656
2657	/**
2658	* Send a nice hexadecimal dump of a buffer to the specified file stream.
2659	*
2660	* @param f The file stream pointer where the dump should be sent to.
2661	* @param buf buffer
2662	* @param size buffer size
2663	*
2664	* @see av_hex_dump_log, av_pkt_dump2, av_pkt_dump_log2
2665	*/
2666	void av_hex_dump(FILE *f, const uint8_t *buf, int size);
2667
2668	/**
2669	* Send a nice hexadecimal dump of a buffer to the log.
2670	*
2671	* @param avcl A pointer to an arbitrary struct of which the first field is a
2672	* pointer to an AVClass struct.
2673	* @param level The importance level of the message, lower values signifying
2674	* higher importance.
2675	* @param buf buffer
2676	* @param size buffer size
2677	*
2678	* @see av_hex_dump, av_pkt_dump2, av_pkt_dump_log2
2679	*/
2680	void av_hex_dump_log(void *avcl, int level, const uint8_t *buf, int size);
2681
2682	/**
2683	* Send a nice dump of a packet to the specified file stream.
2684	*
2685	* @param f The file stream pointer where the dump should be sent to.
2686	* @param pkt packet to dump
2687	* @param dump_payload True if the payload must be displayed, too.
2688	* @param st AVStream that the packet belongs to
2689	*/
2690	void av_pkt_dump2(FILE *f, const AVPacket *pkt, int dump_payload, const AVStream *st);
2691
2692
2693	/**
2694	* Send a nice dump of a packet to the log.
2695	*
2696	* @param avcl A pointer to an arbitrary struct of which the first field is a
2697	* pointer to an AVClass struct.
2698	* @param level The importance level of the message, lower values signifying
2699	* higher importance.
2700	* @param pkt packet to dump
2701	* @param dump_payload True if the payload must be displayed, too.
2702	* @param st AVStream that the packet belongs to
2703	*/
2704	void av_pkt_dump_log2(void *avcl, int level, const AVPacket *pkt, int dump_payload,
2705	const AVStream *st);
2706
2707	/**
2708	* Get the AVCodecID for the given codec tag tag.
2709	* If no codec id is found returns AV_CODEC_ID_NONE.
2710	*
2711	* @param tags list of supported codec_id-codec_tag pairs, as stored
2712	* in AVInputFormat.codec_tag and AVOutputFormat.codec_tag
2713	* @param tag codec tag to match to a codec ID
2714	*/
2715	enum AVCodecID av_codec_get_id(const struct AVCodecTag * const *tags, unsigned int tag);
2716
2717	/**
2718	* Get the codec tag for the given codec id id.
2719	* If no codec tag is found returns 0.
2720	*
2721	* @param tags list of supported codec_id-codec_tag pairs, as stored
2722	* in AVInputFormat.codec_tag and AVOutputFormat.codec_tag
2723	* @param id codec ID to match to a codec tag
2724	*/
2725	unsigned int av_codec_get_tag(const struct AVCodecTag * const *tags, enum AVCodecID id);
2726
2727	/**
2728	* Get the codec tag for the given codec id.
2729	*
2730	* @param tags list of supported codec_id - codec_tag pairs, as stored
2731	* in AVInputFormat.codec_tag and AVOutputFormat.codec_tag
2732	* @param id codec id that should be searched for in the list
2733	* @param tag A pointer to the found tag
2734	* @return 0 if id was not found in tags, > 0 if it was found
2735	*/
2736	int av_codec_get_tag2(const struct AVCodecTag * const *tags, enum AVCodecID id,
2737	unsigned int *tag);
2738
2739	int av_find_default_stream_index(AVFormatContext *s);
2740
2741	/**
2742	* Get the index for a specific timestamp.
2743	*
2744	* @param st stream that the timestamp belongs to
2745	* @param timestamp timestamp to retrieve the index for
2746	* @param flags if AVSEEK_FLAG_BACKWARD then the returned index will correspond
2747	* to the timestamp which is <= the requested one, if backward
2748	* is 0, then it will be >=
2749	* if AVSEEK_FLAG_ANY seek to any frame, only keyframes otherwise
2750	* @return < 0 if no such timestamp could be found
2751	*/
2752	int av_index_search_timestamp(AVStream *st, int64_t timestamp, int flags);
2753
2754	/**
2755	* Add an index entry into a sorted list. Update the entry if the list
2756	* already contains it.
2757	*
2758	* @param timestamp timestamp in the time base of the given stream
2759	*/
2760	int av_add_index_entry(AVStream *st, int64_t pos, int64_t timestamp,
2761	int size, int distance, int flags);
2762
2763
2764	/**
2765	* Split a URL string into components.
2766	*
2767	* The pointers to buffers for storing individual components may be null,
2768	* in order to ignore that component. Buffers for components not found are
2769	* set to empty strings. If the port is not found, it is set to a negative
2770	* value.
2771	*
2772	* @param proto the buffer for the protocol
2773	* @param proto_size the size of the proto buffer
2774	* @param authorization the buffer for the authorization
2775	* @param authorization_size the size of the authorization buffer
2776	* @param hostname the buffer for the host name
2777	* @param hostname_size the size of the hostname buffer
2778	* @param port_ptr a pointer to store the port number in
2779	* @param path the buffer for the path
2780	* @param path_size the size of the path buffer
2781	* @param url the URL to split
2782	*/
2783	void av_url_split(char *proto, int proto_size,
2784	char *authorization, int authorization_size,
2785	char *hostname, int hostname_size,
2786	int *port_ptr,
2787	char *path, int path_size,
2788	const char *url);
2789
2790
2791	/**
2792	* Print detailed information about the input or output format, such as
2793	* duration, bitrate, streams, container, programs, metadata, side data,
2794	* codec and time base.
2795	*
2796	* @param ic the context to analyze
2797	* @param index index of the stream to dump information about
2798	* @param url the URL to print, such as source or destination file
2799	* @param is_output Select whether the specified context is an input(0) or output(1)
2800	*/
2801	void av_dump_format(AVFormatContext *ic,
2802	int index,
2803	const char *url,
2804	int is_output);
2805
2806
2807	#define AV_FRAME_FILENAME_FLAGS_MULTIPLE 1 ///< Allow multiple %d
2808
2809	/**
2810	* Return in 'buf' the path with '%d' replaced by a number.
2811	*
2812	* Also handles the '%0nd' format where 'n' is the total number
2813	* of digits and '%%'.
2814	*
2815	* @param buf destination buffer
2816	* @param buf_size destination buffer size
2817	* @param path numbered sequence string
2818	* @param number frame number
2819	* @param flags AV_FRAME_FILENAME_FLAGS_*
2820	* @return 0 if OK, -1 on format error
2821	*/
2822	int av_get_frame_filename2(char *buf, int buf_size,
2823	const char *path, int number, int flags);
2824
2825	int av_get_frame_filename(char *buf, int buf_size,
2826	const char *path, int number);
2827
2828	/**
2829	* Check whether filename actually is a numbered sequence generator.
2830	*
2831	* @param filename possible numbered sequence string
2832	* @return 1 if a valid numbered sequence string, 0 otherwise
2833	*/
2834	int av_filename_number_test(const char *filename);
2835
2836	/**
2837	* Generate an SDP for an RTP session.
2838	*
2839	* Note, this overwrites the id values of AVStreams in the muxer contexts
2840	* for getting unique dynamic payload types.
2841	*
2842	* @param ac array of AVFormatContexts describing the RTP streams. If the
2843	* array is composed by only one context, such context can contain
2844	* multiple AVStreams (one AVStream per RTP stream). Otherwise,
2845	* all the contexts in the array (an AVCodecContext per RTP stream)
2846	* must contain only one AVStream.
2847	* @param n_files number of AVCodecContexts contained in ac
2848	* @param buf buffer where the SDP will be stored (must be allocated by
2849	* the caller)
2850	* @param size the size of the buffer
2851	* @return 0 if OK, AVERROR_xxx on error
2852	*/
2853	int av_sdp_create(AVFormatContext *ac[], int n_files, char *buf, int size);
2854
2855	/**
2856	* Return a positive value if the given filename has one of the given
2857	* extensions, 0 otherwise.
2858	*
2859	* @param filename file name to check against the given extensions
2860	* @param extensions a comma-separated list of filename extensions
2861	*/
2862	int av_match_ext(const char *filename, const char *extensions);
2863
2864	/**
2865	* Test if the given container can store a codec.
2866	*
2867	* @param ofmt container to check for compatibility
2868	* @param codec_id codec to potentially store in container
2869	* @param std_compliance standards compliance level, one of FF_COMPLIANCE_*
2870	*
2871	* @return 1 if codec with ID codec_id can be stored in ofmt, 0 if it cannot.
2872	* A negative number if this information is not available.
2873	*/
2874	int avformat_query_codec(const AVOutputFormat *ofmt, enum AVCodecID codec_id,
2875	int std_compliance);
2876
2877	/**
2878	* @defgroup riff_fourcc RIFF FourCCs
2879	* @{
2880	* Get the tables mapping RIFF FourCCs to libavcodec AVCodecIDs. The tables are
2881	* meant to be passed to av_codec_get_id()/av_codec_get_tag() as in the
2882	* following code:
2883	* @code
2884	* uint32_t tag = MKTAG('H', '2', '6', '4');
2885	* const struct AVCodecTag *table[] = { avformat_get_riff_video_tags(), 0 };
2886	* enum AVCodecID id = av_codec_get_id(table, tag);
2887	* @endcode
2888	*/
2889	/**
2890	* @return the table mapping RIFF FourCCs for video to libavcodec AVCodecID.
2891	*/
2892	const struct AVCodecTag *avformat_get_riff_video_tags(void);
2893	/**
2894	* @return the table mapping RIFF FourCCs for audio to AVCodecID.
2895	*/
2896	const struct AVCodecTag *avformat_get_riff_audio_tags(void);
2897	/**
2898	* @return the table mapping MOV FourCCs for video to libavcodec AVCodecID.
2899	*/
2900	const struct AVCodecTag *avformat_get_mov_video_tags(void);
2901	/**
2902	* @return the table mapping MOV FourCCs for audio to AVCodecID.
2903	*/
2904	const struct AVCodecTag *avformat_get_mov_audio_tags(void);
2905
2906	/**
2907	* @}
2908	*/
2909
2910	/**
2911	* Guess the sample aspect ratio of a frame, based on both the stream and the
2912	* frame aspect ratio.
2913	*
2914	* Since the frame aspect ratio is set by the codec but the stream aspect ratio
2915	* is set by the demuxer, these two may not be equal. This function tries to
2916	* return the value that you should use if you would like to display the frame.
2917	*
2918	* Basic logic is to use the stream aspect ratio if it is set to something sane
2919	* otherwise use the frame aspect ratio. This way a container setting, which is
2920	* usually easy to modify can override the coded value in the frames.
2921	*
2922	* @param format the format context which the stream is part of
2923	* @param stream the stream which the frame is part of
2924	* @param frame the frame with the aspect ratio to be determined
2925	* @return the guessed (valid) sample_aspect_ratio, 0/1 if no idea
2926	*/
2927	AVRational av_guess_sample_aspect_ratio(AVFormatContext *format, AVStream *stream, AVFrame *frame);
2928
2929	/**
2930	* Guess the frame rate, based on both the container and codec information.
2931	*
2932	* @param ctx the format context which the stream is part of
2933	* @param stream the stream which the frame is part of
2934	* @param frame the frame for which the frame rate should be determined, may be NULL
2935	* @return the guessed (valid) frame rate, 0/1 if no idea
2936	*/
2937	AVRational av_guess_frame_rate(AVFormatContext *ctx, AVStream *stream, AVFrame *frame);
2938
2939	/**
2940	* Check if the stream st contained in s is matched by the stream specifier
2941	* spec.
2942	*
2943	* See the "stream specifiers" chapter in the documentation for the syntax
2944	* of spec.
2945	*
2946	* @return >0 if st is matched by spec;
2947	* 0 if st is not matched by spec;
2948	* AVERROR code if spec is invalid
2949	*
2950	* @note A stream specifier can match several streams in the format.
2951	*/
2952	int avformat_match_stream_specifier(AVFormatContext *s, AVStream *st,
2953	const char *spec);
2954
2955	int avformat_queue_attached_pictures(AVFormatContext *s);
2956
2957	/**
2958	* Apply a list of bitstream filters to a packet.
2959	*
2960	* @param codec AVCodecContext, usually from an AVStream
2961	* @param pkt the packet to apply filters to. If, on success, the returned
2962	* packet has size == 0 and side_data_elems == 0, it indicates that
2963	* the packet should be dropped
2964	* @param bsfc a NULL-terminated list of filters to apply
2965	* @return >=0 on success;
2966	* AVERROR code on failure
2967	*/
2968	#if FF_API_OLD_BSF
2969	attribute_deprecated
2970	int av_apply_bitstream_filters(AVCodecContext *codec, AVPacket *pkt,
2971	AVBitStreamFilterContext *bsfc);
2972	#endif
2973
2974	enum AVTimebaseSource {
2975	AVFMT_TBCF_AUTO = -1,
2976	AVFMT_TBCF_DECODER,
2977	AVFMT_TBCF_DEMUXER,
2978	#if FF_API_R_FRAME_RATE
2979	AVFMT_TBCF_R_FRAMERATE,
2980	#endif
2981	};
2982
2983	/**
2984	* Transfer internal timing information from one stream to another.
2985	*
2986	* This function is useful when doing stream copy.
2987	*
2988	* @param ofmt target output format for ost
2989	* @param ost output stream which needs timings copy and adjustments
2990	* @param ist reference input stream to copy timings from
2991	* @param copy_tb define from where the stream codec timebase needs to be imported
2992	*/
2993	int avformat_transfer_internal_stream_timing_info(const AVOutputFormat *ofmt,
2994	AVStream *ost, const AVStream *ist,
2995	enum AVTimebaseSource copy_tb);
2996
2997	/**
2998	* Get the internal codec timebase from a stream.
2999	*
3000	* @param st input stream to extract the timebase from
3001	*/
3002	AVRational av_stream_get_codec_timebase(const AVStream *st);
3003
3004	/**
3005	* @}
3006	*/
3007
3008	#endif /* AVFORMAT_AVFORMAT_H */
3009