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 I/O and Muxing/Demuxing Library
32	* @{
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	* Lavf allows to configure 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	* @defgroup lavf_decoding Demuxing
82	* @{
83	* Demuxers read a media file and split it into chunks of data (@em packets). A
84	* @ref AVPacket "packet" contains one or more encoded frames which belongs to a
85	* single elementary stream. In the lavf API this process is represented by the
86	* avformat_open_input() function for opening a file, av_read_frame() for
87	* reading a single packet and finally avformat_close_input(), which does the
88	* cleanup.
89	*
90	* @section lavf_decoding_open Opening a media file
91	* The minimum information required to open a file is its URL or filename, which
92	* is passed to avformat_open_input(), as in the following code:
93	* @code
94	* const char *url = "in.mp3";
95	* AVFormatContext *s = NULL;
96	* int ret = avformat_open_input(&s, url, NULL, NULL);
97	* if (ret < 0)
98	* abort();
99	* @endcode
100	* The above code attempts to allocate an AVFormatContext, open the
101	* specified file (autodetecting the format) and read the header, exporting the
102	* information stored there into s. Some formats do not have a header or do not
103	* store enough information there, so it is recommended that you call the
104	* avformat_find_stream_info() function which tries to read and decode a few
105	* frames to find missing information.
106	*
107	* In some cases you might want to preallocate an AVFormatContext yourself with
108	* avformat_alloc_context() and do some tweaking on it before passing it to
109	* avformat_open_input(). One such case is when you want to use custom functions
110	* for reading input data instead of lavf internal I/O layer.
111	* To do that, create your own AVIOContext with avio_alloc_context(), passing
112	* your reading callbacks to it. Then set the @em pb field of your
113	* AVFormatContext to newly created AVIOContext.
114	*
115	* Since the format of the opened file is in general not known until after
116	* avformat_open_input() has returned, it is not possible to set demuxer private
117	* options on a preallocated context. Instead, the options should be passed to
118	* avformat_open_input() wrapped in an AVDictionary:
119	* @code
120	* AVDictionary *options = NULL;
121	* av_dict_set(&options, "video_size", "640x480", 0);
122	* av_dict_set(&options, "pixel_format", "rgb24", 0);
123	*
124	* if (avformat_open_input(&s, url, NULL, &options) < 0)
125	* abort();
126	* av_dict_free(&options);
127	* @endcode
128	* This code passes the private options 'video_size' and 'pixel_format' to the
129	* demuxer. They would be necessary for e.g. the rawvideo demuxer, since it
130	* cannot know how to interpret raw video data otherwise. If the format turns
131	* out to be something different than raw video, those options will not be
132	* recognized by the demuxer and therefore will not be applied. Such unrecognized
133	* options are then returned in the options dictionary (recognized options are
134	* consumed). The calling program can handle such unrecognized options as it
135	* wishes, e.g.
136	* @code
137	* AVDictionaryEntry *e;
138	* if (e = av_dict_get(options, "", NULL, AV_DICT_IGNORE_SUFFIX)) {
139	* fprintf(stderr, "Option %s not recognized by the demuxer.\n", e->key);
140	* abort();
141	* }
142	* @endcode
143	*
144	* After you have finished reading the file, you must close it with
145	* avformat_close_input(). It will free everything associated with the file.
146	*
147	* @section lavf_decoding_read Reading from an opened file
148	* Reading data from an opened AVFormatContext is done by repeatedly calling
149	* av_read_frame() on it. Each call, if successful, will return an AVPacket
150	* containing encoded data for one AVStream, identified by
151	* AVPacket.stream_index. This packet may be passed straight into the libavcodec
152	* decoding functions avcodec_decode_video2(), avcodec_decode_audio4() or
153	* avcodec_decode_subtitle2() if the caller wishes to decode the data.
154	*
155	* AVPacket.pts, AVPacket.dts and AVPacket.duration timing information will be
156	* set if known. They may also be unset (i.e. AV_NOPTS_VALUE for
157	* pts/dts, 0 for duration) if the stream does not provide them. The timing
158	* information will be in AVStream.time_base units, i.e. it has to be
159	* multiplied by the timebase to convert them to seconds.
160	*
161	* If AVPacket.buf is set on the returned packet, then the packet is
162	* allocated dynamically and the user may keep it indefinitely.
163	* Otherwise, if AVPacket.buf is NULL, the packet data is backed by a
164	* static storage somewhere inside the demuxer and the packet is only valid
165	* until the next av_read_frame() call or closing the file. If the caller
166	* requires a longer lifetime, av_dup_packet() will make an av_malloc()ed copy
167	* of it.
168	* In both cases, the packet must be freed with av_free_packet() when it is no
169	* longer needed.
170	*
171	* @section lavf_decoding_seek Seeking
172	* @}
173	*
174	* @defgroup lavf_encoding Muxing
175	* @{
176	* @}
177	*
178	* @defgroup lavf_io I/O Read/Write
179	* @{
180	* @}
181	*
182	* @defgroup lavf_codec Demuxers
183	* @{
184	* @defgroup lavf_codec_native Native Demuxers
185	* @{
186	* @}
187	* @defgroup lavf_codec_wrappers External library wrappers
188	* @{
189	* @}
190	* @}
191	* @defgroup lavf_protos I/O Protocols
192	* @{
193	* @}
194	* @defgroup lavf_internal Internal
195	* @{
196	* @}
197	* @}
198	*
199	*/
200
201	#include <time.h>
202	#include <stdio.h> /* FILE */
203	#include "libavcodec/avcodec.h"
204	#include "libavutil/dict.h"
205	#include "libavutil/log.h"
206
207	#include "avio.h"
208	#include "libavformat/version.h"
209
210	struct AVFormatContext;
211
212
213	/**
214	* @defgroup metadata_api Public Metadata API
215	* @{
216	* @ingroup libavf
217	* The metadata API allows libavformat to export metadata tags to a client
218	* application when demuxing. Conversely it allows a client application to
219	* set metadata when muxing.
220	*
221	* Metadata is exported or set as pairs of key/value strings in the 'metadata'
222	* fields of the AVFormatContext, AVStream, AVChapter and AVProgram structs
223	* using the @ref lavu_dict "AVDictionary" API. Like all strings in FFmpeg,
224	* metadata is assumed to be UTF-8 encoded Unicode. Note that metadata
225	* exported by demuxers isn't checked to be valid UTF-8 in most cases.
226	*
227	* Important concepts to keep in mind:
228	* - Keys are unique; there can never be 2 tags with the same key. This is
229	* also meant semantically, i.e., a demuxer should not knowingly produce
230	* several keys that are literally different but semantically identical.
231	* E.g., key=Author5, key=Author6. In this example, all authors must be
232	* placed in the same tag.
233	* - Metadata is flat, not hierarchical; there are no subtags. If you
234	* want to store, e.g., the email address of the child of producer Alice
235	* and actor Bob, that could have key=alice_and_bobs_childs_email_address.
236	* - Several modifiers can be applied to the tag name. This is done by
237	* appending a dash character ('-') and the modifier name in the order
238	* they appear in the list below -- e.g. foo-eng-sort, not foo-sort-eng.
239	* - language -- a tag whose value is localized for a particular language
240	* is appended with the ISO 639-2/B 3-letter language code.
241	* For example: Author-ger=Michael, Author-eng=Mike
242	* The original/default language is in the unqualified "Author" tag.
243	* A demuxer should set a default if it sets any translated tag.
244	* - sorting -- a modified version of a tag that should be used for
245	* sorting will have '-sort' appended. E.g. artist="The Beatles",
246	* artist-sort="Beatles, The".
247	*
248	* - Demuxers attempt to export metadata in a generic format, however tags
249	* with no generic equivalents are left as they are stored in the container.
250	* Follows a list of generic tag names:
251	*
252	@verbatim
253	album -- name of the set this work belongs to
254	album_artist -- main creator of the set/album, if different from artist.
255	e.g. "Various Artists" for compilation albums.
256	artist -- main creator of the work
257	comment -- any additional description of the file.
258	composer -- who composed the work, if different from artist.
259	copyright -- name of copyright holder.
260	creation_time-- date when the file was created, preferably in ISO 8601.
261	date -- date when the work was created, preferably in ISO 8601.
262	disc -- number of a subset, e.g. disc in a multi-disc collection.
263	encoder -- name/settings of the software/hardware that produced the file.
264	encoded_by -- person/group who created the file.
265	filename -- original name of the file.
266	genre -- <self-evident>.
267	language -- main language in which the work is performed, preferably
268	in ISO 639-2 format. Multiple languages can be specified by
269	separating them with commas.
270	performer -- artist who performed the work, if different from artist.
271	E.g for "Also sprach Zarathustra", artist would be "Richard
272	Strauss" and performer "London Philharmonic Orchestra".
273	publisher -- name of the label/publisher.
274	service_name -- name of the service in broadcasting (channel name).
275	service_provider -- name of the service provider in broadcasting.
276	title -- name of the work.
277	track -- number of this work in the set, can be in form current/total.
278	variant_bitrate -- the total bitrate of the bitrate variant that the current stream is part of
279	@endverbatim
280	*
281	* Look in the examples section for an application example how to use the Metadata API.
282	*
283	* @}
284	*/
285
286	/* packet functions */
287
288
289	/**
290	* Allocate and read the payload of a packet and initialize its
291	* fields with default values.
292	*
293	* @param pkt packet
294	* @param size desired payload size
295	* @return >0 (read size) if OK, AVERROR_xxx otherwise
296	*/
297	int av_get_packet(AVIOContext *s, AVPacket *pkt, int size);
298
299
300	/**
301	* Read data and append it to the current content of the AVPacket.
302	* If pkt->size is 0 this is identical to av_get_packet.
303	* Note that this uses av_grow_packet and thus involves a realloc
304	* which is inefficient. Thus this function should only be used
305	* when there is no reasonable way to know (an upper bound of)
306	* the final size.
307	*
308	* @param pkt packet
309	* @param size amount of data to read
310	* @return >0 (read size) if OK, AVERROR_xxx otherwise, previous data
311	* will not be lost even if an error occurs.
312	*/
313	int av_append_packet(AVIOContext *s, AVPacket *pkt, int size);
314
315	/*************************************************/
316	/* fractional numbers for exact pts handling */
317
318	/**
319	* The exact value of the fractional number is: 'val + num / den'.
320	* num is assumed to be 0 <= num < den.
321	*/
322	typedef struct AVFrac {
323	int64_t val, num, den;
324	} AVFrac;
325
326	/*************************************************/
327	/* input/output formats */
328
329	struct AVCodecTag;
330
331	/**
332	* This structure contains the data a format has to probe a file.
333	*/
334	typedef struct AVProbeData {
335	const char *filename;
336	unsigned char *buf; /**< Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero. */
337	int buf_size; /**< Size of buf except extra allocated bytes */
338	} AVProbeData;
339
340	#define AVPROBE_SCORE_RETRY (AVPROBE_SCORE_MAX/4)
341	#define AVPROBE_SCORE_EXTENSION 50 ///< score for file extension
342	#define AVPROBE_SCORE_MAX 100 ///< maximum score
343
344	#define AVPROBE_PADDING_SIZE 32 ///< extra allocated bytes at the end of the probe buffer
345
346	/// Demuxer will use avio_open, no opened file should be provided by the caller.
347	#define AVFMT_NOFILE 0x0001
348	#define AVFMT_NEEDNUMBER 0x0002 /**< Needs '%d' in filename. */
349	#define AVFMT_SHOW_IDS 0x0008 /**< Show format stream IDs numbers. */
350	#define AVFMT_RAWPICTURE 0x0020 /**< Format wants AVPicture structure for
351	raw picture data. */
352	#define AVFMT_GLOBALHEADER 0x0040 /**< Format wants global header. */
353	#define AVFMT_NOTIMESTAMPS 0x0080 /**< Format does not need / have any timestamps. */
354	#define AVFMT_GENERIC_INDEX 0x0100 /**< Use generic index building code. */
355	#define AVFMT_TS_DISCONT 0x0200 /**< Format allows timestamp discontinuities. Note, muxers always require valid (monotone) timestamps */
356	#define AVFMT_VARIABLE_FPS 0x0400 /**< Format allows variable fps. */
357	#define AVFMT_NODIMENSIONS 0x0800 /**< Format does not need width/height */
358	#define AVFMT_NOSTREAMS 0x1000 /**< Format does not require any streams */
359	#define AVFMT_NOBINSEARCH 0x2000 /**< Format does not allow to fall back on binary search via read_timestamp */
360	#define AVFMT_NOGENSEARCH 0x4000 /**< Format does not allow to fall back on generic search */
361	#define AVFMT_NO_BYTE_SEEK 0x8000 /**< Format does not allow seeking by bytes */
362	#define AVFMT_ALLOW_FLUSH 0x10000 /**< Format allows flushing. If not set, the muxer will not receive a NULL packet in the write_packet function. */
363	#if LIBAVFORMAT_VERSION_MAJOR <= 54
364	#define AVFMT_TS_NONSTRICT 0x8020000 //we try to be compatible to the ABIs of ffmpeg and major forks
365	#else
366	#define AVFMT_TS_NONSTRICT 0x20000
367	#endif
368	/**< Format does not require strictly
369	increasing timestamps, but they must
370	still be monotonic */
371	#define AVFMT_TS_NEGATIVE 0x40000 /**< Format allows muxing negative
372	timestamps. If not set the timestamp
373	will be shifted in av_write_frame and
374	av_interleaved_write_frame so they
375	start from 0.
376	The user or muxer can override this through
377	AVFormatContext.avoid_negative_ts
378	*/
379
380	#define AVFMT_SEEK_TO_PTS 0x4000000 /**< Seeking is based on PTS */
381
382	/**
383	* @addtogroup lavf_encoding
384	* @{
385	*/
386	typedef struct AVOutputFormat {
387	const char *name;
388	/**
389	* Descriptive name for the format, meant to be more human-readable
390	* than name. You should use the NULL_IF_CONFIG_SMALL() macro
391	* to define it.
392	*/
393	const char *long_name;
394	const char *mime_type;
395	const char *extensions; /**< comma-separated filename extensions */
396	/* output support */
397	enum AVCodecID audio_codec; /**< default audio codec */
398	enum AVCodecID video_codec; /**< default video codec */
399	enum AVCodecID subtitle_codec; /**< default subtitle codec */
400	/**
401	* can use flags: AVFMT_NOFILE, AVFMT_NEEDNUMBER, AVFMT_RAWPICTURE,
402	* AVFMT_GLOBALHEADER, AVFMT_NOTIMESTAMPS, AVFMT_VARIABLE_FPS,
403	* AVFMT_NODIMENSIONS, AVFMT_NOSTREAMS, AVFMT_ALLOW_FLUSH,
404	* AVFMT_TS_NONSTRICT
405	*/
406	int flags;
407
408	/**
409	* List of supported codec_id-codec_tag pairs, ordered by "better
410	* choice first". The arrays are all terminated by AV_CODEC_ID_NONE.
411	*/
412	const struct AVCodecTag * const *codec_tag;
413
414
415	const AVClass *priv_class; ///< AVClass for the private context
416
417	/*****************************************************************
418	* No fields below this line are part of the public API. They
419	* may not be used outside of libavformat and can be changed and
420	* removed at will.
421	* New public fields should be added right above.
422	*****************************************************************
423	*/
424	struct AVOutputFormat *next;
425	/**
426	* size of private data so that it can be allocated in the wrapper
427	*/
428	int priv_data_size;
429
430	int (*write_header)(struct AVFormatContext *);
431	/**
432	* Write a packet. If AVFMT_ALLOW_FLUSH is set in flags,
433	* pkt can be NULL in order to flush data buffered in the muxer.
434	* When flushing, return 0 if there still is more data to flush,
435	* or 1 if everything was flushed and there is no more buffered
436	* data.
437	*/
438	int (*write_packet)(struct AVFormatContext *, AVPacket *pkt);
439	int (*write_trailer)(struct AVFormatContext *);
440	/**
441	* Currently only used to set pixel format if not YUV420P.
442	*/
443	int (*interleave_packet)(struct AVFormatContext *, AVPacket *out,
444	AVPacket *in, int flush);
445	/**
446	* Test if the given codec can be stored in this container.
447	*
448	* @return 1 if the codec is supported, 0 if it is not.
449	* A negative number if unknown.
450	* MKTAG('A', 'P', 'I', 'C') if the codec is only supported as AV_DISPOSITION_ATTACHED_PIC
451	*/
452	int (*query_codec)(enum AVCodecID id, int std_compliance);
453
454	void (*get_output_timestamp)(struct AVFormatContext *s, int stream,
455	int64_t *dts, int64_t *wall);
456	} AVOutputFormat;
457	/**
458	* @}
459	*/
460
461	/**
462	* @addtogroup lavf_decoding
463	* @{
464	*/
465	typedef struct AVInputFormat {
466	/**
467	* A comma separated list of short names for the format. New names
468	* may be appended with a minor bump.
469	*/
470	const char *name;
471
472	/**
473	* Descriptive name for the format, meant to be more human-readable
474	* than name. You should use the NULL_IF_CONFIG_SMALL() macro
475	* to define it.
476	*/
477	const char *long_name;
478
479	/**
480	* Can use flags: AVFMT_NOFILE, AVFMT_NEEDNUMBER, AVFMT_SHOW_IDS,
481	* AVFMT_GENERIC_INDEX, AVFMT_TS_DISCONT, AVFMT_NOBINSEARCH,
482	* AVFMT_NOGENSEARCH, AVFMT_NO_BYTE_SEEK, AVFMT_SEEK_TO_PTS.
483	*/
484	int flags;
485
486	/**
487	* If extensions are defined, then no probe is done. You should
488	* usually not use extension format guessing because it is not
489	* reliable enough
490	*/
491	const char *extensions;
492
493	const struct AVCodecTag * const *codec_tag;
494
495	const AVClass *priv_class; ///< AVClass for the private context
496
497	/*****************************************************************
498	* No fields below this line are part of the public API. They
499	* may not be used outside of libavformat and can be changed and
500	* removed at will.
501	* New public fields should be added right above.
502	*****************************************************************
503	*/
504	struct AVInputFormat *next;
505
506	/**
507	* Raw demuxers store their codec ID here.
508	*/
509	int raw_codec_id;
510
511	/**
512	* Size of private data so that it can be allocated in the wrapper.
513	*/
514	int priv_data_size;
515
516	/**
517	* Tell if a given file has a chance of being parsed as this format.
518	* The buffer provided is guaranteed to be AVPROBE_PADDING_SIZE bytes
519	* big so you do not have to check for that unless you need more.
520	*/
521	int (*read_probe)(AVProbeData *);
522
523	/**
524	* Read the format header and initialize the AVFormatContext
525	* structure. Return 0 if OK. Only used in raw format right
526	* now. 'avformat_new_stream' should be called to create new streams.
527	*/
528	int (*read_header)(struct AVFormatContext *);
529
530	/**
531	* Read one packet and put it in 'pkt'. pts and flags are also
532	* set. 'avformat_new_stream' can be called only if the flag
533	* AVFMTCTX_NOHEADER is used and only in the calling thread (not in a
534	* background thread).
535	* @return 0 on success, < 0 on error.
536	* When returning an error, pkt must not have been allocated
537	* or must be freed before returning
538	*/
539	int (*read_packet)(struct AVFormatContext *, AVPacket *pkt);
540
541	/**
542	* Close the stream. The AVFormatContext and AVStreams are not
543	* freed by this function
544	*/
545	int (*read_close)(struct AVFormatContext *);
546
547	/**
548	* Seek to a given timestamp relative to the frames in
549	* stream component stream_index.
550	* @param stream_index Must not be -1.
551	* @param flags Selects which direction should be preferred if no exact
552	* match is available.
553	* @return >= 0 on success (but not necessarily the new offset)
554	*/
555	int (*read_seek)(struct AVFormatContext *,
556	int stream_index, int64_t timestamp, int flags);
557
558	/**
559	* Get the next timestamp in stream[stream_index].time_base units.
560	* @return the timestamp or AV_NOPTS_VALUE if an error occurred
561	*/
562	int64_t (*read_timestamp)(struct AVFormatContext *s, int stream_index,
563	int64_t *pos, int64_t pos_limit);
564
565	/**
566	* Start/resume playing - only meaningful if using a network-based format
567	* (RTSP).
568	*/
569	int (*read_play)(struct AVFormatContext *);
570
571	/**
572	* Pause playing - only meaningful if using a network-based format
573	* (RTSP).
574	*/
575	int (*read_pause)(struct AVFormatContext *);
576
577	/**
578	* Seek to timestamp ts.
579	* Seeking will be done so that the point from which all active streams
580	* can be presented successfully will be closest to ts and within min/max_ts.
581	* Active streams are all streams that have AVStream.discard < AVDISCARD_ALL.
582	*/
583	int (*read_seek2)(struct AVFormatContext *s, int stream_index, int64_t min_ts, int64_t ts, int64_t max_ts, int flags);
584	} AVInputFormat;
585	/**
586	* @}
587	*/
588
589	enum AVStreamParseType {
590	AVSTREAM_PARSE_NONE,
591	AVSTREAM_PARSE_FULL, /**< full parsing and repack */
592	AVSTREAM_PARSE_HEADERS, /**< Only parse headers, do not repack. */
593	AVSTREAM_PARSE_TIMESTAMPS, /**< full parsing and interpolation of timestamps for frames not starting on a packet boundary */
594	AVSTREAM_PARSE_FULL_ONCE, /**< full parsing and repack of the first frame only, only implemented for H.264 currently */
595	AVSTREAM_PARSE_FULL_RAW=MKTAG(0,'R','A','W'), /**< full parsing and repack with timestamp and position generation by parser for raw
596	this assumes that each packet in the file contains no demuxer level headers and
597	just codec level data, otherwise position generation would fail */
598	};
599
600	typedef struct AVIndexEntry {
601	int64_t pos;
602	int64_t timestamp; /**<
603	* Timestamp in AVStream.time_base units, preferably the time from which on correctly decoded frames are available
604	* when seeking to this entry. That means preferable PTS on keyframe based formats.
605	* But demuxers can choose to store a different timestamp, if it is more convenient for the implementation or nothing better
606	* is known
607	*/
608	#define AVINDEX_KEYFRAME 0x0001
609	int flags:2;
610	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).
611	int min_distance; /**< Minimum distance between this and the previous keyframe, used to avoid unneeded searching. */
612	} AVIndexEntry;
613
614	#define AV_DISPOSITION_DEFAULT 0x0001
615	#define AV_DISPOSITION_DUB 0x0002
616	#define AV_DISPOSITION_ORIGINAL 0x0004
617	#define AV_DISPOSITION_COMMENT 0x0008
618	#define AV_DISPOSITION_LYRICS 0x0010
619	#define AV_DISPOSITION_KARAOKE 0x0020
620
621	/**
622	* Track should be used during playback by default.
623	* Useful for subtitle track that should be displayed
624	* even when user did not explicitly ask for subtitles.
625	*/
626	#define AV_DISPOSITION_FORCED 0x0040
627	#define AV_DISPOSITION_HEARING_IMPAIRED 0x0080 /**< stream for hearing impaired audiences */
628	#define AV_DISPOSITION_VISUAL_IMPAIRED 0x0100 /**< stream for visual impaired audiences */
629	#define AV_DISPOSITION_CLEAN_EFFECTS 0x0200 /**< stream without voice */
630	/**
631	* The stream is stored in the file as an attached picture/"cover art" (e.g.
632	* APIC frame in ID3v2). The single packet associated with it will be returned
633	* among the first few packets read from the file unless seeking takes place.
634	* It can also be accessed at any time in AVStream.attached_pic.
635	*/
636	#define AV_DISPOSITION_ATTACHED_PIC 0x0400
637
638	/**
639	* To specify text track kind (different from subtitles default).
640	*/
641	#define AV_DISPOSITION_CAPTIONS 0x10000
642	#define AV_DISPOSITION_DESCRIPTIONS 0x20000
643	#define AV_DISPOSITION_METADATA 0x40000
644
645	/**
646	* Options for behavior on timestamp wrap detection.
647	*/
648	#define AV_PTS_WRAP_IGNORE 0 ///< ignore the wrap
649	#define AV_PTS_WRAP_ADD_OFFSET 1 ///< add the format specific offset on wrap detection
650	#define AV_PTS_WRAP_SUB_OFFSET -1 ///< subtract the format specific offset on wrap detection
651
652	/**
653	* Stream structure.
654	* New fields can be added to the end with minor version bumps.
655	* Removal, reordering and changes to existing fields require a major
656	* version bump.
657	* sizeof(AVStream) must not be used outside libav*.
658	*/
659	typedef struct AVStream {
660	int index; /**< stream index in AVFormatContext */
661	/**
662	* Format-specific stream ID.
663	* decoding: set by libavformat
664	* encoding: set by the user, replaced by libavformat if left unset
665	*/
666	int id;
667	/**
668	* Codec context associated with this stream. Allocated and freed by
669	* libavformat.
670	*
671	* - decoding: The demuxer exports codec information stored in the headers
672	* here.
673	* - encoding: The user sets codec information, the muxer writes it to the
674	* output. Mandatory fields as specified in AVCodecContext
675	* documentation must be set even if this AVCodecContext is
676	* not actually used for encoding.
677	*/
678	AVCodecContext *codec;
679	void *priv_data;
680
681	/**
682	* encoding: pts generation when outputting stream
683	*/
684	struct AVFrac pts;
685
686	/**
687	* This is the fundamental unit of time (in seconds) in terms
688	* of which frame timestamps are represented.
689	*
690	* decoding: set by libavformat
691	* encoding: set by libavformat in avformat_write_header. The muxer may use the
692	* user-provided value of @ref AVCodecContext.time_base "codec->time_base"
693	* as a hint.
694	*/
695	AVRational time_base;
696
697	/**
698	* Decoding: pts of the first frame of the stream in presentation order, in stream time base.
699	* Only set this if you are absolutely 100% sure that the value you set
700	* it to really is the pts of the first frame.
701	* This may be undefined (AV_NOPTS_VALUE).
702	* @note The ASF header does NOT contain a correct start_time the ASF
703	* demuxer must NOT set this.
704	*/
705	int64_t start_time;
706
707	/**
708	* Decoding: duration of the stream, in stream time base.
709	* If a source file does not specify a duration, but does specify
710	* a bitrate, this value will be estimated from bitrate and file size.
711	*/
712	int64_t duration;
713
714	int64_t nb_frames; ///< number of frames in this stream if known or 0
715
716	int disposition; /**< AV_DISPOSITION_* bit field */
717
718	enum AVDiscard discard; ///< Selects which packets can be discarded at will and do not need to be demuxed.
719
720	/**
721	* sample aspect ratio (0 if unknown)
722	* - encoding: Set by user.
723	* - decoding: Set by libavformat.
724	*/
725	AVRational sample_aspect_ratio;
726
727	AVDictionary *metadata;
728
729	/**
730	* Average framerate
731	*/
732	AVRational avg_frame_rate;
733
734	/**
735	* For streams with AV_DISPOSITION_ATTACHED_PIC disposition, this packet
736	* will contain the attached picture.
737	*
738	* decoding: set by libavformat, must not be modified by the caller.
739	* encoding: unused
740	*/
741	AVPacket attached_pic;
742
743	/*****************************************************************
744	* All fields below this line are not part of the public API. They
745	* may not be used outside of libavformat and can be changed and
746	* removed at will.
747	* New public fields should be added right above.
748	*****************************************************************
749	*/
750
751	/**
752	* Stream information used internally by av_find_stream_info()
753	*/
754	#define MAX_STD_TIMEBASES (60*12+6)
755	struct {
756	int64_t last_dts;
757	int64_t duration_gcd;
758	int duration_count;
759	double (*duration_error)[2][MAX_STD_TIMEBASES];
760	int64_t codec_info_duration;
761	int64_t codec_info_duration_fields;
762	int found_decoder;
763
764	int64_t last_duration;
765
766	/**
767	* Those are used for average framerate estimation.
768	*/
769	int64_t fps_first_dts;
770	int fps_first_dts_idx;
771	int64_t fps_last_dts;
772	int fps_last_dts_idx;
773
774	} *info;
775
776	int pts_wrap_bits; /**< number of bits in pts (used for wrapping control) */
777
778	// Timestamp generation support:
779	/**
780	* Timestamp corresponding to the last dts sync point.
781	*
782	* Initialized when AVCodecParserContext.dts_sync_point >= 0 and
783	* a DTS is received from the underlying container. Otherwise set to
784	* AV_NOPTS_VALUE by default.
785	*/
786	int64_t reference_dts;
787	int64_t first_dts;
788	int64_t cur_dts;
789	int64_t last_IP_pts;
790	int last_IP_duration;
791
792	/**
793	* Number of packets to buffer for codec probing
794	*/
795	#define MAX_PROBE_PACKETS 2500
796	int probe_packets;
797
798	/**
799	* Number of frames that have been demuxed during av_find_stream_info()
800	*/
801	int codec_info_nb_frames;
802
803	/* av_read_frame() support */
804	enum AVStreamParseType need_parsing;
805	struct AVCodecParserContext *parser;
806
807	/**
808	* last packet in packet_buffer for this stream when muxing.
809	*/
810	struct AVPacketList *last_in_packet_buffer;
811	AVProbeData probe_data;
812	#define MAX_REORDER_DELAY 16
813	int64_t pts_buffer[MAX_REORDER_DELAY+1];
814
815	AVIndexEntry *index_entries; /**< Only used if the format does not
816	support seeking natively. */
817	int nb_index_entries;
818	unsigned int index_entries_allocated_size;
819
820	/**
821	* Real base framerate of the stream.
822	* This is the lowest framerate with which all timestamps can be
823	* represented accurately (it is the least common multiple of all
824	* framerates in the stream). Note, this value is just a guess!
825	* For example, if the time base is 1/90000 and all frames have either
826	* approximately 3600 or 1800 timer ticks, then r_frame_rate will be 50/1.
827	*
828	* Code outside avformat should access this field using:
829	* av_stream_get/set_r_frame_rate(stream)
830	*/
831	AVRational r_frame_rate;
832
833	/**
834	* Stream Identifier
835	* This is the MPEG-TS stream identifier +1
836	* 0 means unknown
837	*/
838	int stream_identifier;
839
840	int64_t interleaver_chunk_size;
841	int64_t interleaver_chunk_duration;
842
843	/**
844	* stream probing state
845	* -1 -> probing finished
846	* 0 -> no probing requested
847	* rest -> perform probing with request_probe being the minimum score to accept.
848	* NOT PART OF PUBLIC API
849	*/
850	int request_probe;
851	/**
852	* Indicates that everything up to the next keyframe
853	* should be discarded.
854	*/
855	int skip_to_keyframe;
856
857	/**
858	* Number of samples to skip at the start of the frame decoded from the next packet.
859	*/
860	int skip_samples;
861
862	/**
863	* Number of internally decoded frames, used internally in libavformat, do not access
864	* its lifetime differs from info which is why it is not in that structure.
865	*/
866	int nb_decoded_frames;
867
868	/**
869	* Timestamp offset added to timestamps before muxing
870	* NOT PART OF PUBLIC API
871	*/
872	int64_t mux_ts_offset;
873
874	/**
875	* Internal data to check for wrapping of the time stamp
876	*/
877	int64_t pts_wrap_reference;
878
879	/**
880	* Options for behavior, when a wrap is detected.
881	*
882	* Defined by AV_PTS_WRAP_ values.
883	*
884	* If correction is enabled, there are two possibilities:
885	* If the first time stamp is near the wrap point, the wrap offset
886	* will be subtracted, which will create negative time stamps.
887	* Otherwise the offset will be added.
888	*/
889	int pts_wrap_behavior;
890
891	} AVStream;
892
893	AVRational av_stream_get_r_frame_rate(const AVStream *s);
894	void av_stream_set_r_frame_rate(AVStream *s, AVRational r);
895
896	#define AV_PROGRAM_RUNNING 1
897
898	/**
899	* New fields can be added to the end with minor version bumps.
900	* Removal, reordering and changes to existing fields require a major
901	* version bump.
902	* sizeof(AVProgram) must not be used outside libav*.
903	*/
904	typedef struct AVProgram {
905	int id;
906	int flags;
907	enum AVDiscard discard; ///< selects which program to discard and which to feed to the caller
908	unsigned int *stream_index;
909	unsigned int nb_stream_indexes;
910	AVDictionary *metadata;
911
912	int program_num;
913	int pmt_pid;
914	int pcr_pid;
915
916	/*****************************************************************
917	* All fields below this line are not part of the public API. They
918	* may not be used outside of libavformat and can be changed and
919	* removed at will.
920	* New public fields should be added right above.
921	*****************************************************************
922	*/
923	int64_t start_time;
924	int64_t end_time;
925
926	int64_t pts_wrap_reference; ///< reference dts for wrap detection
927	int pts_wrap_behavior; ///< behavior on wrap detection
928	} AVProgram;
929
930	#define AVFMTCTX_NOHEADER 0x0001 /**< signal that no header is present
931	(streams are added dynamically) */
932
933	typedef struct AVChapter {
934	int id; ///< unique ID to identify the chapter
935	AVRational time_base; ///< time base in which the start/end timestamps are specified
936	int64_t start, end; ///< chapter start/end time in time_base units
937	AVDictionary *metadata;
938	} AVChapter;
939
940
941	/**
942	* The duration of a video can be estimated through various ways, and this enum can be used
943	* to know how the duration was estimated.
944	*/
945	enum AVDurationEstimationMethod {
946	AVFMT_DURATION_FROM_PTS, ///< Duration accurately estimated from PTSes
947	AVFMT_DURATION_FROM_STREAM, ///< Duration estimated from a stream with a known duration
948	AVFMT_DURATION_FROM_BITRATE ///< Duration estimated from bitrate (less accurate)
949	};
950
951	/**
952	* Format I/O context.
953	* New fields can be added to the end with minor version bumps.
954	* Removal, reordering and changes to existing fields require a major
955	* version bump.
956	* sizeof(AVFormatContext) must not be used outside libav*, use
957	* avformat_alloc_context() to create an AVFormatContext.
958	*/
959	typedef struct AVFormatContext {
960	/**
961	* A class for logging and AVOptions. Set by avformat_alloc_context().
962	* Exports (de)muxer private options if they exist.
963	*/
964	const AVClass *av_class;
965
966	/**
967	* Can only be iformat or oformat, not both at the same time.
968	*
969	* decoding: set by avformat_open_input().
970	* encoding: set by the user.
971	*/
972	struct AVInputFormat *iformat;
973	struct AVOutputFormat *oformat;
974
975	/**
976	* Format private data. This is an AVOptions-enabled struct
977	* if and only if iformat/oformat.priv_class is not NULL.
978	*/
979	void *priv_data;
980
981	/**
982	* I/O context.
983	*
984	* decoding: either set by the user before avformat_open_input() (then
985	* the user must close it manually) or set by avformat_open_input().
986	* encoding: set by the user.
987	*
988	* Do NOT set this field if AVFMT_NOFILE flag is set in
989	* iformat/oformat.flags. In such a case, the (de)muxer will handle
990	* I/O in some other way and this field will be NULL.
991	*/
992	AVIOContext *pb;
993
994	/* stream info */
995	int ctx_flags; /**< Format-specific flags, see AVFMTCTX_xx */
996
997	/**
998	* A list of all streams in the file. New streams are created with
999	* avformat_new_stream().
1000	*
1001	* decoding: streams are created by libavformat in avformat_open_input().
1002	* If AVFMTCTX_NOHEADER is set in ctx_flags, then new streams may also
1003	* appear in av_read_frame().
1004	* encoding: streams are created by the user before avformat_write_header().
1005	*/
1006	unsigned int nb_streams;
1007	AVStream **streams;
1008
1009	char filename[1024]; /**< input or output filename */
1010
1011	/**
1012	* Decoding: position of the first frame of the component, in
1013	* AV_TIME_BASE fractional seconds. NEVER set this value directly:
1014	* It is deduced from the AVStream values.
1015	*/
1016	int64_t start_time;
1017
1018	/**
1019	* Decoding: duration of the stream, in AV_TIME_BASE fractional
1020	* seconds. Only set this value if you know none of the individual stream
1021	* durations and also do not set any of them. This is deduced from the
1022	* AVStream values if not set.
1023	*/
1024	int64_t duration;
1025
1026	/**
1027	* Decoding: total stream bitrate in bit/s, 0 if not
1028	* available. Never set it directly if the file_size and the
1029	* duration are known as FFmpeg can compute it automatically.
1030	*/
1031	int bit_rate;
1032
1033	unsigned int packet_size;
1034	int max_delay;
1035
1036	int flags;
1037	#define AVFMT_FLAG_GENPTS 0x0001 ///< Generate missing pts even if it requires parsing future frames.
1038	#define AVFMT_FLAG_IGNIDX 0x0002 ///< Ignore index.
1039	#define AVFMT_FLAG_NONBLOCK 0x0004 ///< Do not block when reading packets from input.
1040	#define AVFMT_FLAG_IGNDTS 0x0008 ///< Ignore DTS on frames that contain both DTS & PTS
1041	#define AVFMT_FLAG_NOFILLIN 0x0010 ///< Do not infer any values from other values, just return what is stored in the container
1042	#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
1043	#define AVFMT_FLAG_NOBUFFER 0x0040 ///< Do not buffer frames when possible
1044	#define AVFMT_FLAG_CUSTOM_IO 0x0080 ///< The caller has supplied a custom AVIOContext, don't avio_close() it.
1045	#define AVFMT_FLAG_DISCARD_CORRUPT 0x0100 ///< Discard frames marked corrupted
1046	#define AVFMT_FLAG_FLUSH_PACKETS 0x0200 ///< Flush the AVIOContext every packet.
1047	#define AVFMT_FLAG_MP4A_LATM 0x8000 ///< Enable RTP MP4A-LATM payload
1048	#define AVFMT_FLAG_SORT_DTS 0x10000 ///< try to interleave outputted packets by dts (using this flag can slow demuxing down)
1049	#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)
1050	#define AVFMT_FLAG_KEEP_SIDE_DATA 0x40000 ///< Don't merge side data but keep it separate.
1051
1052	/**
1053	* decoding: size of data to probe; encoding: unused.
1054	*/
1055	unsigned int probesize;
1056
1057	/**
1058	* decoding: maximum time (in AV_TIME_BASE units) during which the input should
1059	* be analyzed in avformat_find_stream_info().
1060	*/
1061	int max_analyze_duration;
1062
1063	const uint8_t *key;
1064	int keylen;
1065
1066	unsigned int nb_programs;
1067	AVProgram **programs;
1068
1069	/**
1070	* Forced video codec_id.
1071	* Demuxing: Set by user.
1072	*/
1073	enum AVCodecID video_codec_id;
1074
1075	/**
1076	* Forced audio codec_id.
1077	* Demuxing: Set by user.
1078	*/
1079	enum AVCodecID audio_codec_id;
1080
1081	/**
1082	* Forced subtitle codec_id.
1083	* Demuxing: Set by user.
1084	*/
1085	enum AVCodecID subtitle_codec_id;
1086
1087	/**
1088	* Maximum amount of memory in bytes to use for the index of each stream.
1089	* If the index exceeds this size, entries will be discarded as
1090	* needed to maintain a smaller size. This can lead to slower or less
1091	* accurate seeking (depends on demuxer).
1092	* Demuxers for which a full in-memory index is mandatory will ignore
1093	* this.
1094	* muxing : unused
1095	* demuxing: set by user
1096	*/
1097	unsigned int max_index_size;
1098
1099	/**
1100	* Maximum amount of memory in bytes to use for buffering frames
1101	* obtained from realtime capture devices.
1102	*/
1103	unsigned int max_picture_buffer;
1104
1105	/**
1106	* Number of chapters in AVChapter array.
1107	* When muxing, chapters are normally written in the file header,
1108	* so nb_chapters should normally be initialized before write_header
1109	* is called. Some muxers (e.g. mov and mkv) can also write chapters
1110	* in the trailer. To write chapters in the trailer, nb_chapters
1111	* must be zero when write_header is called and non-zero when
1112	* write_trailer is called.
1113	* muxing : set by user
1114	* demuxing: set by libavformat
1115	*/
1116	unsigned int nb_chapters;
1117	AVChapter **chapters;
1118
1119	AVDictionary *metadata;
1120
1121	/**
1122	* Start time of the stream in real world time, in microseconds
1123	* since the unix epoch (00:00 1st January 1970). That is, pts=0
1124	* in the stream was captured at this real world time.
1125	* - encoding: Set by user.
1126	* - decoding: Unused.
1127	*/
1128	int64_t start_time_realtime;
1129
1130	/**
1131	* decoding: number of frames used to probe fps
1132	*/
1133	int fps_probe_size;
1134
1135	/**
1136	* Error recognition; higher values will detect more errors but may
1137	* misdetect some more or less valid parts as errors.
1138	* - encoding: unused
1139	* - decoding: Set by user.
1140	*/
1141	int error_recognition;
1142
1143	/**
1144	* Custom interrupt callbacks for the I/O layer.
1145	*
1146	* decoding: set by the user before avformat_open_input().
1147	* encoding: set by the user before avformat_write_header()
1148	* (mainly useful for AVFMT_NOFILE formats). The callback
1149	* should also be passed to avio_open2() if it's used to
1150	* open the file.
1151	*/
1152	AVIOInterruptCB interrupt_callback;
1153
1154	/**
1155	* Flags to enable debugging.
1156	*/
1157	int debug;
1158	#define FF_FDEBUG_TS 0x0001
1159
1160	/**
1161	* Transport stream id.
1162	* This will be moved into demuxer private options. Thus no API/ABI compatibility
1163	*/
1164	int ts_id;
1165
1166	/**
1167	* Audio preload in microseconds.
1168	* Note, not all formats support this and unpredictable things may happen if it is used when not supported.
1169	* - encoding: Set by user via AVOptions (NO direct access)
1170	* - decoding: unused
1171	*/
1172	int audio_preload;
1173
1174	/**
1175	* Max chunk time in microseconds.
1176	* Note, not all formats support this and unpredictable things may happen if it is used when not supported.
1177	* - encoding: Set by user via AVOptions (NO direct access)
1178	* - decoding: unused
1179	*/
1180	int max_chunk_duration;
1181
1182	/**
1183	* Max chunk size in bytes
1184	* Note, not all formats support this and unpredictable things may happen if it is used when not supported.
1185	* - encoding: Set by user via AVOptions (NO direct access)
1186	* - decoding: unused
1187	*/
1188	int max_chunk_size;
1189
1190	/**
1191	* forces the use of wallclock timestamps as pts/dts of packets
1192	* This has undefined results in the presence of B frames.
1193	* - encoding: unused
1194	* - decoding: Set by user via AVOptions (NO direct access)
1195	*/
1196	int use_wallclock_as_timestamps;
1197
1198	/**
1199	* Avoid negative timestamps during muxing.
1200	* 0 -> allow negative timestamps
1201	* 1 -> avoid negative timestamps
1202	* -1 -> choose automatically (default)
1203	* Note, this only works when interleave_packet_per_dts is in use.
1204	* - encoding: Set by user via AVOptions (NO direct access)
1205	* - decoding: unused
1206	*/
1207	int avoid_negative_ts;
1208
1209	/**
1210	* avio flags, used to force AVIO_FLAG_DIRECT.
1211	* - encoding: unused
1212	* - decoding: Set by user via AVOptions (NO direct access)
1213	*/
1214	int avio_flags;
1215
1216	/**
1217	* The duration field can be estimated through various ways, and this field can be used
1218	* to know how the duration was estimated.
1219	* - encoding: unused
1220	* - decoding: Read by user via AVOptions (NO direct access)
1221	*/
1222	enum AVDurationEstimationMethod duration_estimation_method;
1223
1224	/**
1225	* Skip initial bytes when opening stream
1226	* - encoding: unused
1227	* - decoding: Set by user via AVOptions (NO direct access)
1228	*/
1229	unsigned int skip_initial_bytes;
1230
1231	/**
1232	* Correct single timestamp overflows
1233	* - encoding: unused
1234	* - decoding: Set by user via AVOPtions (NO direct access)
1235	*/
1236	unsigned int correct_ts_overflow;
1237
1238	/**
1239	* Force seeking to any (also non key) frames.
1240	* - encoding: unused
1241	* - decoding: Set by user via AVOPtions (NO direct access)
1242	*/
1243	int seek2any;
1244
1245	/**
1246	* Flush the I/O context after each packet.
1247	* - encoding: Set by user via AVOptions (NO direct access)
1248	* - decoding: unused
1249	*/
1250	int flush_packets;
1251
1252	/**
1253	* format probing score.
1254	* The maximal score is AVPROBE_SCORE_MAX, its set when the demuxer probes
1255	* the format.
1256	* - encoding: unused
1257	* - decoding: set by avformat, read by user via av_format_get_probe_score() (NO direct access)
1258	*/
1259	int probe_score;
1260
1261	/*****************************************************************
1262	* All fields below this line are not part of the public API. They
1263	* may not be used outside of libavformat and can be changed and
1264	* removed at will.
1265	* New public fields should be added right above.
1266	*****************************************************************
1267	*/
1268
1269	/**
1270	* This buffer is only needed when packets were already buffered but
1271	* not decoded, for example to get the codec parameters in MPEG
1272	* streams.
1273	*/
1274	struct AVPacketList *packet_buffer;
1275	struct AVPacketList *packet_buffer_end;
1276
1277	/* av_seek_frame() support */
1278	int64_t data_offset; /**< offset of the first packet */
1279
1280	/**
1281	* Raw packets from the demuxer, prior to parsing and decoding.
1282	* This buffer is used for buffering packets until the codec can
1283	* be identified, as parsing cannot be done without knowing the
1284	* codec.
1285	*/
1286	struct AVPacketList *raw_packet_buffer;
1287	struct AVPacketList *raw_packet_buffer_end;
1288	/**
1289	* Packets split by the parser get queued here.
1290	*/
1291	struct AVPacketList *parse_queue;
1292	struct AVPacketList *parse_queue_end;
1293	/**
1294	* Remaining size available for raw_packet_buffer, in bytes.
1295	*/
1296	#define RAW_PACKET_BUFFER_SIZE 2500000
1297	int raw_packet_buffer_remaining_size;
1298
1299	/**
1300	* Offset to remap timestamps to be non-negative.
1301	* Expressed in timebase units.
1302	* @see AVStream.mux_ts_offset
1303	*/
1304	int64_t offset;
1305
1306	/**
1307	* Timebase for the timestamp offset.
1308	*/
1309	AVRational offset_timebase;
1310
1311	/**
1312	* IO repositioned flag.
1313	* This is set by avformat when the underlaying IO context read pointer
1314	* is repositioned, for example when doing byte based seeking.
1315	* Demuxers can use the flag to detect such changes.
1316	*/
1317	int io_repositioned;
1318
1319	/**
1320	* Forced video codec.
1321	* This allows forcing a specific decoder, even when there are multiple with
1322	* the same codec_id.
1323	* Demuxing: Set by user via av_format_set_video_codec (NO direct access).
1324	*/
1325	AVCodec *video_codec;
1326
1327	/**
1328	* Forced audio codec.
1329	* This allows forcing a specific decoder, even when there are multiple with
1330	* the same codec_id.
1331	* Demuxing: Set by user via av_format_set_audio_codec (NO direct access).
1332	*/
1333	AVCodec *audio_codec;
1334
1335	/**
1336	* Forced subtitle codec.
1337	* This allows forcing a specific decoder, even when there are multiple with
1338	* the same codec_id.
1339	* Demuxing: Set by user via av_format_set_subtitle_codec (NO direct access).
1340	*/
1341	AVCodec *subtitle_codec;
1342	} AVFormatContext;
1343
1344	int av_format_get_probe_score(const AVFormatContext *s);
1345	AVCodec * av_format_get_video_codec(const AVFormatContext *s);
1346	void av_format_set_video_codec(AVFormatContext *s, AVCodec *c);
1347	AVCodec * av_format_get_audio_codec(const AVFormatContext *s);
1348	void av_format_set_audio_codec(AVFormatContext *s, AVCodec *c);
1349	AVCodec * av_format_get_subtitle_codec(const AVFormatContext *s);
1350	void av_format_set_subtitle_codec(AVFormatContext *s, AVCodec *c);
1351
1352	/**
1353	* Returns the method used to set ctx->duration.
1354	*
1355	* @return AVFMT_DURATION_FROM_PTS, AVFMT_DURATION_FROM_STREAM, or AVFMT_DURATION_FROM_BITRATE.
1356	*/
1357	enum AVDurationEstimationMethod av_fmt_ctx_get_duration_estimation_method(const AVFormatContext* ctx);
1358
1359	typedef struct AVPacketList {
1360	AVPacket pkt;
1361	struct AVPacketList *next;
1362	} AVPacketList;
1363
1364
1365	/**
1366	* @defgroup lavf_core Core functions
1367	* @ingroup libavf
1368	*
1369	* Functions for querying libavformat capabilities, allocating core structures,
1370	* etc.
1371	* @{
1372	*/
1373
1374	/**
1375	* Return the LIBAVFORMAT_VERSION_INT constant.
1376	*/
1377	unsigned avformat_version(void);
1378
1379	/**
1380	* Return the libavformat build-time configuration.
1381	*/
1382	const char *avformat_configuration(void);
1383
1384	/**
1385	* Return the libavformat license.
1386	*/
1387	const char *avformat_license(void);
1388
1389	/**
1390	* Initialize libavformat and register all the muxers, demuxers and
1391	* protocols. If you do not call this function, then you can select
1392	* exactly which formats you want to support.
1393	*
1394	* @see av_register_input_format()
1395	* @see av_register_output_format()
1396	*/
1397	void av_register_all(void);
1398
1399	void av_register_input_format(AVInputFormat *format);
1400	void av_register_output_format(AVOutputFormat *format);
1401
1402	/**
1403	* Do global initialization of network components. This is optional,
1404	* but recommended, since it avoids the overhead of implicitly
1405	* doing the setup for each session.
1406	*
1407	* Calling this function will become mandatory if using network
1408	* protocols at some major version bump.
1409	*/
1410	int avformat_network_init(void);
1411
1412	/**
1413	* Undo the initialization done by avformat_network_init.
1414	*/
1415	int avformat_network_deinit(void);
1416
1417	/**
1418	* If f is NULL, returns the first registered input format,
1419	* if f is non-NULL, returns the next registered input format after f
1420	* or NULL if f is the last one.
1421	*/
1422	AVInputFormat *av_iformat_next(AVInputFormat *f);
1423
1424	/**
1425	* If f is NULL, returns the first registered output format,
1426	* if f is non-NULL, returns the next registered output format after f
1427	* or NULL if f is the last one.
1428	*/
1429	AVOutputFormat *av_oformat_next(AVOutputFormat *f);
1430
1431	/**
1432	* Allocate an AVFormatContext.
1433	* avformat_free_context() can be used to free the context and everything
1434	* allocated by the framework within it.
1435	*/
1436	AVFormatContext *avformat_alloc_context(void);
1437
1438	/**
1439	* Free an AVFormatContext and all its streams.
1440	* @param s context to free
1441	*/
1442	void avformat_free_context(AVFormatContext *s);
1443
1444	/**
1445	* Get the AVClass for AVFormatContext. It can be used in combination with
1446	* AV_OPT_SEARCH_FAKE_OBJ for examining options.
1447	*
1448	* @see av_opt_find().
1449	*/
1450	const AVClass *avformat_get_class(void);
1451
1452	/**
1453	* Add a new stream to a media file.
1454	*
1455	* When demuxing, it is called by the demuxer in read_header(). If the
1456	* flag AVFMTCTX_NOHEADER is set in s.ctx_flags, then it may also
1457	* be called in read_packet().
1458	*
1459	* When muxing, should be called by the user before avformat_write_header().
1460	*
1461	* User is required to call avcodec_close() and avformat_free_context() to
1462	* clean up the allocation by avformat_new_stream().
1463	*
1464	* @param c If non-NULL, the AVCodecContext corresponding to the new stream
1465	* will be initialized to use this codec. This is needed for e.g. codec-specific
1466	* defaults to be set, so codec should be provided if it is known.
1467	*
1468	* @return newly created stream or NULL on error.
1469	*/
1470	AVStream *avformat_new_stream(AVFormatContext *s, const AVCodec *c);
1471
1472	AVProgram *av_new_program(AVFormatContext *s, int id);
1473
1474	/**
1475	* @}
1476	*/
1477
1478
1479	#if FF_API_ALLOC_OUTPUT_CONTEXT
1480	/**
1481	* @deprecated deprecated in favor of avformat_alloc_output_context2()
1482	*/
1483	attribute_deprecated
1484	AVFormatContext *avformat_alloc_output_context(const char *format,
1485	AVOutputFormat *oformat,
1486	const char *filename);
1487	#endif
1488
1489	/**
1490	* Allocate an AVFormatContext for an output format.
1491	* avformat_free_context() can be used to free the context and
1492	* everything allocated by the framework within it.
1493	*
1494	* @param *ctx is set to the created format context, or to NULL in
1495	* case of failure
1496	* @param oformat format to use for allocating the context, if NULL
1497	* format_name and filename are used instead
1498	* @param format_name the name of output format to use for allocating the
1499	* context, if NULL filename is used instead
1500	* @param filename the name of the filename to use for allocating the
1501	* context, may be NULL
1502	* @return >= 0 in case of success, a negative AVERROR code in case of
1503	* failure
1504	*/
1505	int avformat_alloc_output_context2(AVFormatContext **ctx, AVOutputFormat *oformat,
1506	const char *format_name, const char *filename);
1507
1508	/**
1509	* @addtogroup lavf_decoding
1510	* @{
1511	*/
1512
1513	/**
1514	* Find AVInputFormat based on the short name of the input format.
1515	*/
1516	AVInputFormat *av_find_input_format(const char *short_name);
1517
1518	/**
1519	* Guess the file format.
1520	*
1521	* @param is_opened Whether the file is already opened; determines whether
1522	* demuxers with or without AVFMT_NOFILE are probed.
1523	*/
1524	AVInputFormat *av_probe_input_format(AVProbeData *pd, int is_opened);
1525
1526	/**
1527	* Guess the file format.
1528	*
1529	* @param is_opened Whether the file is already opened; determines whether
1530	* demuxers with or without AVFMT_NOFILE are probed.
1531	* @param score_max A probe score larger that this is required to accept a
1532	* detection, the variable is set to the actual detection
1533	* score afterwards.
1534	* If the score is <= AVPROBE_SCORE_MAX / 4 it is recommended
1535	* to retry with a larger probe buffer.
1536	*/
1537	AVInputFormat *av_probe_input_format2(AVProbeData *pd, int is_opened, int *score_max);
1538
1539	/**
1540	* Guess the file format.
1541	*
1542	* @param is_opened Whether the file is already opened; determines whether
1543	* demuxers with or without AVFMT_NOFILE are probed.
1544	* @param score_ret The score of the best detection.
1545	*/
1546	AVInputFormat *av_probe_input_format3(AVProbeData *pd, int is_opened, int *score_ret);
1547
1548	/**
1549	* Probe a bytestream to determine the input format. Each time a probe returns
1550	* with a score that is too low, the probe buffer size is increased and another
1551	* attempt is made. When the maximum probe size is reached, the input format
1552	* with the highest score is returned.
1553	*
1554	* @param pb the bytestream to probe
1555	* @param fmt the input format is put here
1556	* @param filename the filename of the stream
1557	* @param logctx the log context
1558	* @param offset the offset within the bytestream to probe from
1559	* @param max_probe_size the maximum probe buffer size (zero for default)
1560	* @return the score in case of success, a negative value corresponding to an
1561	* the maximal score is AVPROBE_SCORE_MAX
1562	* AVERROR code otherwise
1563	*/
1564	int av_probe_input_buffer2(AVIOContext *pb, AVInputFormat **fmt,
1565	const char *filename, void *logctx,
1566	unsigned int offset, unsigned int max_probe_size);
1567
1568	/**
1569	* Like av_probe_input_buffer2() but returns 0 on success
1570	*/
1571	int av_probe_input_buffer(AVIOContext *pb, AVInputFormat **fmt,
1572	const char *filename, void *logctx,
1573	unsigned int offset, unsigned int max_probe_size);
1574
1575	/**
1576	* Open an input stream and read the header. The codecs are not opened.
1577	* The stream must be closed with avformat_close_input().
1578	*
1579	* @param ps Pointer to user-supplied AVFormatContext (allocated by avformat_alloc_context).
1580	* May be a pointer to NULL, in which case an AVFormatContext is allocated by this
1581	* function and written into ps.
1582	* Note that a user-supplied AVFormatContext will be freed on failure.
1583	* @param filename Name of the stream to open.
1584	* @param fmt If non-NULL, this parameter forces a specific input format.
1585	* Otherwise the format is autodetected.
1586	* @param options A dictionary filled with AVFormatContext and demuxer-private options.
1587	* On return this parameter will be destroyed and replaced with a dict containing
1588	* options that were not found. May be NULL.
1589	*
1590	* @return 0 on success, a negative AVERROR on failure.
1591	*
1592	* @note If you want to use custom IO, preallocate the format context and set its pb field.
1593	*/
1594	int avformat_open_input(AVFormatContext **ps, const char *filename, AVInputFormat *fmt, AVDictionary **options);
1595
1596	attribute_deprecated
1597	int av_demuxer_open(AVFormatContext *ic);
1598
1599	#if FF_API_FORMAT_PARAMETERS
1600	/**
1601	* Read packets of a media file to get stream information. This
1602	* is useful for file formats with no headers such as MPEG. This
1603	* function also computes the real framerate in case of MPEG-2 repeat
1604	* frame mode.
1605	* The logical file position is not changed by this function;
1606	* examined packets may be buffered for later processing.
1607	*
1608	* @param ic media file handle
1609	* @return >=0 if OK, AVERROR_xxx on error
1610	* @todo Let the user decide somehow what information is needed so that
1611	* we do not waste time getting stuff the user does not need.
1612	*
1613	* @deprecated use avformat_find_stream_info.
1614	*/
1615	attribute_deprecated
1616	int av_find_stream_info(AVFormatContext *ic);
1617	#endif
1618
1619	/**
1620	* Read packets of a media file to get stream information. This
1621	* is useful for file formats with no headers such as MPEG. This
1622	* function also computes the real framerate in case of MPEG-2 repeat
1623	* frame mode.
1624	* The logical file position is not changed by this function;
1625	* examined packets may be buffered for later processing.
1626	*
1627	* @param ic media file handle
1628	* @param options If non-NULL, an ic.nb_streams long array of pointers to
1629	* dictionaries, where i-th member contains options for
1630	* codec corresponding to i-th stream.
1631	* On return each dictionary will be filled with options that were not found.
1632	* @return >=0 if OK, AVERROR_xxx on error
1633	*
1634	* @note this function isn't guaranteed to open all the codecs, so
1635	* options being non-empty at return is a perfectly normal behavior.
1636	*
1637	* @todo Let the user decide somehow what information is needed so that
1638	* we do not waste time getting stuff the user does not need.
1639	*/
1640	int avformat_find_stream_info(AVFormatContext *ic, AVDictionary **options);
1641
1642	/**
1643	* Find the programs which belong to a given stream.
1644	*
1645	* @param ic media file handle
1646	* @param last the last found program, the search will start after this
1647	* program, or from the beginning if it is NULL
1648	* @param s stream index
1649	* @return the next program which belongs to s, NULL if no program is found or
1650	* the last program is not among the programs of ic.
1651	*/
1652	AVProgram *av_find_program_from_stream(AVFormatContext *ic, AVProgram *last, int s);
1653
1654	/**
1655	* Find the "best" stream in the file.
1656	* The best stream is determined according to various heuristics as the most
1657	* likely to be what the user expects.
1658	* If the decoder parameter is non-NULL, av_find_best_stream will find the
1659	* default decoder for the stream's codec; streams for which no decoder can
1660	* be found are ignored.
1661	*
1662	* @param ic media file handle
1663	* @param type stream type: video, audio, subtitles, etc.
1664	* @param wanted_stream_nb user-requested stream number,
1665	* or -1 for automatic selection
1666	* @param related_stream try to find a stream related (eg. in the same
1667	* program) to this one, or -1 if none
1668	* @param decoder_ret if non-NULL, returns the decoder for the
1669	* selected stream
1670	* @param flags flags; none are currently defined
1671	* @return the non-negative stream number in case of success,
1672	* AVERROR_STREAM_NOT_FOUND if no stream with the requested type
1673	* could be found,
1674	* AVERROR_DECODER_NOT_FOUND if streams were found but no decoder
1675	* @note If av_find_best_stream returns successfully and decoder_ret is not
1676	* NULL, then *decoder_ret is guaranteed to be set to a valid AVCodec.
1677	*/
1678	int av_find_best_stream(AVFormatContext *ic,
1679	enum AVMediaType type,
1680	int wanted_stream_nb,
1681	int related_stream,
1682	AVCodec **decoder_ret,
1683	int flags);
1684
1685	#if FF_API_READ_PACKET
1686	/**
1687	* @deprecated use AVFMT_FLAG_NOFILLIN | AVFMT_FLAG_NOPARSE to read raw
1688	* unprocessed packets
1689	*
1690	* Read a transport packet from a media file.
1691	*
1692	* This function is obsolete and should never be used.
1693	* Use av_read_frame() instead.
1694	*
1695	* @param s media file handle
1696	* @param pkt is filled
1697	* @return 0 if OK, AVERROR_xxx on error
1698	*/
1699	attribute_deprecated
1700	int av_read_packet(AVFormatContext *s, AVPacket *pkt);
1701	#endif
1702
1703	/**
1704	* Return the next frame of a stream.
1705	* This function returns what is stored in the file, and does not validate
1706	* that what is there are valid frames for the decoder. It will split what is
1707	* stored in the file into frames and return one for each call. It will not
1708	* omit invalid data between valid frames so as to give the decoder the maximum
1709	* information possible for decoding.
1710	*
1711	* If pkt->buf is NULL, then the packet is valid until the next
1712	* av_read_frame() or until avformat_close_input(). Otherwise the packet
1713	* is valid indefinitely. In both cases the packet must be freed with
1714	* av_free_packet when it is no longer needed. For video, the packet contains
1715	* exactly one frame. For audio, it contains an integer number of frames if each
1716	* frame has a known fixed size (e.g. PCM or ADPCM data). If the audio frames
1717	* have a variable size (e.g. MPEG audio), then it contains one frame.
1718	*
1719	* pkt->pts, pkt->dts and pkt->duration are always set to correct
1720	* values in AVStream.time_base units (and guessed if the format cannot
1721	* provide them). pkt->pts can be AV_NOPTS_VALUE if the video format
1722	* has B-frames, so it is better to rely on pkt->dts if you do not
1723	* decompress the payload.
1724	*
1725	* @return 0 if OK, < 0 on error or end of file
1726	*/
1727	int av_read_frame(AVFormatContext *s, AVPacket *pkt);
1728
1729	/**
1730	* Seek to the keyframe at timestamp.
1731	* 'timestamp' in 'stream_index'.
1732	* @param stream_index If stream_index is (-1), a default
1733	* stream is selected, and timestamp is automatically converted
1734	* from AV_TIME_BASE units to the stream specific time_base.
1735	* @param timestamp Timestamp in AVStream.time_base units
1736	* or, if no stream is specified, in AV_TIME_BASE units.
1737	* @param flags flags which select direction and seeking mode
1738	* @return >= 0 on success
1739	*/
1740	int av_seek_frame(AVFormatContext *s, int stream_index, int64_t timestamp,
1741	int flags);
1742
1743	/**
1744	* Seek to timestamp ts.
1745	* Seeking will be done so that the point from which all active streams
1746	* can be presented successfully will be closest to ts and within min/max_ts.
1747	* Active streams are all streams that have AVStream.discard < AVDISCARD_ALL.
1748	*
1749	* If flags contain AVSEEK_FLAG_BYTE, then all timestamps are in bytes and
1750	* are the file position (this may not be supported by all demuxers).
1751	* If flags contain AVSEEK_FLAG_FRAME, then all timestamps are in frames
1752	* in the stream with stream_index (this may not be supported by all demuxers).
1753	* Otherwise all timestamps are in units of the stream selected by stream_index
1754	* or if stream_index is -1, in AV_TIME_BASE units.
1755	* If flags contain AVSEEK_FLAG_ANY, then non-keyframes are treated as
1756	* keyframes (this may not be supported by all demuxers).
1757	* If flags contain AVSEEK_FLAG_BACKWARD, it is ignored.
1758	*
1759	* @param stream_index index of the stream which is used as time base reference
1760	* @param min_ts smallest acceptable timestamp
1761	* @param ts target timestamp
1762	* @param max_ts largest acceptable timestamp
1763	* @param flags flags
1764	* @return >=0 on success, error code otherwise
1765	*
1766	* @note This is part of the new seek API which is still under construction.
1767	* Thus do not use this yet. It may change at any time, do not expect
1768	* ABI compatibility yet!
1769	*/
1770	int avformat_seek_file(AVFormatContext *s, int stream_index, int64_t min_ts, int64_t ts, int64_t max_ts, int flags);
1771
1772	/**
1773	* Start playing a network-based stream (e.g. RTSP stream) at the
1774	* current position.
1775	*/
1776	int av_read_play(AVFormatContext *s);
1777
1778	/**
1779	* Pause a network-based stream (e.g. RTSP stream).
1780	*
1781	* Use av_read_play() to resume it.
1782	*/
1783	int av_read_pause(AVFormatContext *s);
1784
1785	#if FF_API_CLOSE_INPUT_FILE
1786	/**
1787	* @deprecated use avformat_close_input()
1788	* Close a media file (but not its codecs).
1789	*
1790	* @param s media file handle
1791	*/
1792	attribute_deprecated
1793	void av_close_input_file(AVFormatContext *s);
1794	#endif
1795
1796	/**
1797	* Close an opened input AVFormatContext. Free it and all its contents
1798	* and set *s to NULL.
1799	*/
1800	void avformat_close_input(AVFormatContext **s);
1801	/**
1802	* @}
1803	*/
1804
1805	#if FF_API_NEW_STREAM
1806	/**
1807	* Add a new stream to a media file.
1808	*
1809	* Can only be called in the read_header() function. If the flag
1810	* AVFMTCTX_NOHEADER is in the format context, then new streams
1811	* can be added in read_packet too.
1812	*
1813	* @param s media file handle
1814	* @param id file-format-dependent stream ID
1815	*/
1816	attribute_deprecated
1817	AVStream *av_new_stream(AVFormatContext *s, int id);
1818	#endif
1819
1820	#if FF_API_SET_PTS_INFO
1821	/**
1822	* @deprecated this function is not supposed to be called outside of lavf
1823	*/
1824	attribute_deprecated
1825	void av_set_pts_info(AVStream *s, int pts_wrap_bits,
1826	unsigned int pts_num, unsigned int pts_den);
1827	#endif
1828
1829	#define AVSEEK_FLAG_BACKWARD 1 ///< seek backward
1830	#define AVSEEK_FLAG_BYTE 2 ///< seeking based on position in bytes
1831	#define AVSEEK_FLAG_ANY 4 ///< seek to any frame, even non-keyframes
1832	#define AVSEEK_FLAG_FRAME 8 ///< seeking based on frame number
1833
1834	/**
1835	* @addtogroup lavf_encoding
1836	* @{
1837	*/
1838	/**
1839	* Allocate the stream private data and write the stream header to
1840	* an output media file.
1841	*
1842	* @param s Media file handle, must be allocated with avformat_alloc_context().
1843	* Its oformat field must be set to the desired output format;
1844	* Its pb field must be set to an already opened AVIOContext.
1845	* @param options An AVDictionary filled with AVFormatContext and muxer-private options.
1846	* On return this parameter will be destroyed and replaced with a dict containing
1847	* options that were not found. May be NULL.
1848	*
1849	* @return 0 on success, negative AVERROR on failure.
1850	*
1851	* @see av_opt_find, av_dict_set, avio_open, av_oformat_next.
1852	*/
1853	int avformat_write_header(AVFormatContext *s, AVDictionary **options);
1854
1855	/**
1856	* Write a packet to an output media file.
1857	*
1858	* The packet shall contain one audio or video frame.
1859	* The packet must be correctly interleaved according to the container
1860	* specification, if not then av_interleaved_write_frame must be used.
1861	*
1862	* @param s media file handle
1863	* @param pkt The packet, which contains the stream_index, buf/buf_size,
1864	* dts/pts, ...
1865	* This can be NULL (at any time, not just at the end), in
1866	* order to immediately flush data buffered within the muxer,
1867	* for muxers that buffer up data internally before writing it
1868	* to the output.
1869	* @return < 0 on error, = 0 if OK, 1 if flushed and there is no more data to flush
1870	*/
1871	int av_write_frame(AVFormatContext *s, AVPacket *pkt);
1872
1873	/**
1874	* Write a packet to an output media file ensuring correct interleaving.
1875	*
1876	* The packet must contain one audio or video frame.
1877	* If the packets are already correctly interleaved, the application should
1878	* call av_write_frame() instead as it is slightly faster. It is also important
1879	* to keep in mind that completely non-interleaved input will need huge amounts
1880	* of memory to interleave with this, so it is preferable to interleave at the
1881	* demuxer level.
1882	*
1883	* @param s media file handle
1884	* @param pkt The packet containing the data to be written. pkt->buf must be set
1885	* to a valid AVBufferRef describing the packet data. Libavformat takes
1886	* ownership of this reference and will unref it when it sees fit. The caller
1887	* must not access the data through this reference after this function returns.
1888	* This can be NULL (at any time, not just at the end), to flush the
1889	* interleaving queues.
1890	* Packet's @ref AVPacket.stream_index "stream_index" field must be set to the
1891	* index of the corresponding stream in @ref AVFormatContext.streams
1892	* "s.streams".
1893	* It is very strongly recommended that timing information (@ref AVPacket.pts
1894	* "pts", @ref AVPacket.dts "dts" @ref AVPacket.duration "duration") is set to
1895	* correct values.
1896	*
1897	* @return 0 on success, a negative AVERROR on error.
1898	*/
1899	int av_interleaved_write_frame(AVFormatContext *s, AVPacket *pkt);
1900
1901	/**
1902	* Write the stream trailer to an output media file and free the
1903	* file private data.
1904	*
1905	* May only be called after a successful call to avformat_write_header.
1906	*
1907	* @param s media file handle
1908	* @return 0 if OK, AVERROR_xxx on error
1909	*/
1910	int av_write_trailer(AVFormatContext *s);
1911
1912	/**
1913	* Return the output format in the list of registered output formats
1914	* which best matches the provided parameters, or return NULL if
1915	* there is no match.
1916	*
1917	* @param short_name if non-NULL checks if short_name matches with the
1918	* names of the registered formats
1919	* @param filename if non-NULL checks if filename terminates with the
1920	* extensions of the registered formats
1921	* @param mime_type if non-NULL checks if mime_type matches with the
1922	* MIME type of the registered formats
1923	*/
1924	AVOutputFormat *av_guess_format(const char *short_name,
1925	const char *filename,
1926	const char *mime_type);
1927
1928	/**
1929	* Guess the codec ID based upon muxer and filename.
1930	*/
1931	enum AVCodecID av_guess_codec(AVOutputFormat *fmt, const char *short_name,
1932	const char *filename, const char *mime_type,
1933	enum AVMediaType type);
1934
1935	/**
1936	* Get timing information for the data currently output.
1937	* The exact meaning of "currently output" depends on the format.
1938	* It is mostly relevant for devices that have an internal buffer and/or
1939	* work in real time.
1940	* @param s media file handle
1941	* @param stream stream in the media file
1942	* @param[out] dts DTS of the last packet output for the stream, in stream
1943	* time_base units
1944	* @param[out] wall absolute time when that packet whas output,
1945	* in microsecond
1946	* @return 0 if OK, AVERROR(ENOSYS) if the format does not support it
1947	* Note: some formats or devices may not allow to measure dts and wall
1948	* atomically.
1949	*/
1950	int av_get_output_timestamp(struct AVFormatContext *s, int stream,
1951	int64_t *dts, int64_t *wall);
1952
1953
1954	/**
1955	* @}
1956	*/
1957
1958
1959	/**
1960	* @defgroup lavf_misc Utility functions
1961	* @ingroup libavf
1962	* @{
1963	*
1964	* Miscellaneous utility functions related to both muxing and demuxing
1965	* (or neither).
1966	*/
1967
1968	/**
1969	* Send a nice hexadecimal dump of a buffer to the specified file stream.
1970	*
1971	* @param f The file stream pointer where the dump should be sent to.
1972	* @param buf buffer
1973	* @param size buffer size
1974	*
1975	* @see av_hex_dump_log, av_pkt_dump2, av_pkt_dump_log2
1976	*/
1977	void av_hex_dump(FILE *f, const uint8_t *buf, int size);
1978
1979	/**
1980	* Send a nice hexadecimal dump of a buffer to the log.
1981	*
1982	* @param avcl A pointer to an arbitrary struct of which the first field is a
1983	* pointer to an AVClass struct.
1984	* @param level The importance level of the message, lower values signifying
1985	* higher importance.
1986	* @param buf buffer
1987	* @param size buffer size
1988	*
1989	* @see av_hex_dump, av_pkt_dump2, av_pkt_dump_log2
1990	*/
1991	void av_hex_dump_log(void *avcl, int level, const uint8_t *buf, int size);
1992
1993	/**
1994	* Send a nice dump of a packet to the specified file stream.
1995	*
1996	* @param f The file stream pointer where the dump should be sent to.
1997	* @param pkt packet to dump
1998	* @param dump_payload True if the payload must be displayed, too.
1999	* @param st AVStream that the packet belongs to
2000	*/
2001	void av_pkt_dump2(FILE *f, AVPacket *pkt, int dump_payload, AVStream *st);
2002
2003
2004	/**
2005	* Send a nice dump of a packet to the log.
2006	*
2007	* @param avcl A pointer to an arbitrary struct of which the first field is a
2008	* pointer to an AVClass struct.
2009	* @param level The importance level of the message, lower values signifying
2010	* higher importance.
2011	* @param pkt packet to dump
2012	* @param dump_payload True if the payload must be displayed, too.
2013	* @param st AVStream that the packet belongs to
2014	*/
2015	void av_pkt_dump_log2(void *avcl, int level, AVPacket *pkt, int dump_payload,
2016	AVStream *st);
2017
2018	/**
2019	* Get the AVCodecID for the given codec tag tag.
2020	* If no codec id is found returns AV_CODEC_ID_NONE.
2021	*
2022	* @param tags list of supported codec_id-codec_tag pairs, as stored
2023	* in AVInputFormat.codec_tag and AVOutputFormat.codec_tag
2024	*/
2025	enum AVCodecID av_codec_get_id(const struct AVCodecTag * const *tags, unsigned int tag);
2026
2027	/**
2028	* Get the codec tag for the given codec id id.
2029	* If no codec tag is found returns 0.
2030	*
2031	* @param tags list of supported codec_id-codec_tag pairs, as stored
2032	* in AVInputFormat.codec_tag and AVOutputFormat.codec_tag
2033	*/
2034	unsigned int av_codec_get_tag(const struct AVCodecTag * const *tags, enum AVCodecID id);
2035
2036	/**
2037	* Get the codec tag for the given codec id.
2038	*
2039	* @param tags list of supported codec_id - codec_tag pairs, as stored
2040	* in AVInputFormat.codec_tag and AVOutputFormat.codec_tag
2041	* @param id codec id that should be searched for in the list
2042	* @param tag A pointer to the found tag
2043	* @return 0 if id was not found in tags, > 0 if it was found
2044	*/
2045	int av_codec_get_tag2(const struct AVCodecTag * const *tags, enum AVCodecID id,
2046	unsigned int *tag);
2047
2048	int av_find_default_stream_index(AVFormatContext *s);
2049
2050	/**
2051	* Get the index for a specific timestamp.
2052	* @param flags if AVSEEK_FLAG_BACKWARD then the returned index will correspond
2053	* to the timestamp which is <= the requested one, if backward
2054	* is 0, then it will be >=
2055	* if AVSEEK_FLAG_ANY seek to any frame, only keyframes otherwise
2056	* @return < 0 if no such timestamp could be found
2057	*/
2058	int av_index_search_timestamp(AVStream *st, int64_t timestamp, int flags);
2059
2060	/**
2061	* Add an index entry into a sorted list. Update the entry if the list
2062	* already contains it.
2063	*
2064	* @param timestamp timestamp in the time base of the given stream
2065	*/
2066	int av_add_index_entry(AVStream *st, int64_t pos, int64_t timestamp,
2067	int size, int distance, int flags);
2068
2069
2070	/**
2071	* Split a URL string into components.
2072	*
2073	* The pointers to buffers for storing individual components may be null,
2074	* in order to ignore that component. Buffers for components not found are
2075	* set to empty strings. If the port is not found, it is set to a negative
2076	* value.
2077	*
2078	* @param proto the buffer for the protocol
2079	* @param proto_size the size of the proto buffer
2080	* @param authorization the buffer for the authorization
2081	* @param authorization_size the size of the authorization buffer
2082	* @param hostname the buffer for the host name
2083	* @param hostname_size the size of the hostname buffer
2084	* @param port_ptr a pointer to store the port number in
2085	* @param path the buffer for the path
2086	* @param path_size the size of the path buffer
2087	* @param url the URL to split
2088	*/
2089	void av_url_split(char *proto, int proto_size,
2090	char *authorization, int authorization_size,
2091	char *hostname, int hostname_size,
2092	int *port_ptr,
2093	char *path, int path_size,
2094	const char *url);
2095
2096
2097	void av_dump_format(AVFormatContext *ic,
2098	int index,
2099	const char *url,
2100	int is_output);
2101
2102	/**
2103	* Return in 'buf' the path with '%d' replaced by a number.
2104	*
2105	* Also handles the '%0nd' format where 'n' is the total number
2106	* of digits and '%%'.
2107	*
2108	* @param buf destination buffer
2109	* @param buf_size destination buffer size
2110	* @param path numbered sequence string
2111	* @param number frame number
2112	* @return 0 if OK, -1 on format error
2113	*/
2114	int av_get_frame_filename(char *buf, int buf_size,
2115	const char *path, int number);
2116
2117	/**
2118	* Check whether filename actually is a numbered sequence generator.
2119	*
2120	* @param filename possible numbered sequence string
2121	* @return 1 if a valid numbered sequence string, 0 otherwise
2122	*/
2123	int av_filename_number_test(const char *filename);
2124
2125	/**
2126	* Generate an SDP for an RTP session.
2127	*
2128	* Note, this overwrites the id values of AVStreams in the muxer contexts
2129	* for getting unique dynamic payload types.
2130	*
2131	* @param ac array of AVFormatContexts describing the RTP streams. If the
2132	* array is composed by only one context, such context can contain
2133	* multiple AVStreams (one AVStream per RTP stream). Otherwise,
2134	* all the contexts in the array (an AVCodecContext per RTP stream)
2135	* must contain only one AVStream.
2136	* @param n_files number of AVCodecContexts contained in ac
2137	* @param buf buffer where the SDP will be stored (must be allocated by
2138	* the caller)
2139	* @param size the size of the buffer
2140	* @return 0 if OK, AVERROR_xxx on error
2141	*/
2142	int av_sdp_create(AVFormatContext *ac[], int n_files, char *buf, int size);
2143
2144	/**
2145	* Return a positive value if the given filename has one of the given
2146	* extensions, 0 otherwise.
2147	*
2148	* @param extensions a comma-separated list of filename extensions
2149	*/
2150	int av_match_ext(const char *filename, const char *extensions);
2151
2152	/**
2153	* Test if the given container can store a codec.
2154	*
2155	* @param std_compliance standards compliance level, one of FF_COMPLIANCE_*
2156	*
2157	* @return 1 if codec with ID codec_id can be stored in ofmt, 0 if it cannot.
2158	* A negative number if this information is not available.
2159	*/
2160	int avformat_query_codec(AVOutputFormat *ofmt, enum AVCodecID codec_id, int std_compliance);
2161
2162	/**
2163	* @defgroup riff_fourcc RIFF FourCCs
2164	* @{
2165	* Get the tables mapping RIFF FourCCs to libavcodec AVCodecIDs. The tables are
2166	* meant to be passed to av_codec_get_id()/av_codec_get_tag() as in the
2167	* following code:
2168	* @code
2169	* uint32_t tag = MKTAG('H', '2', '6', '4');
2170	* const struct AVCodecTag *table[] = { avformat_get_riff_video_tags(), 0 };
2171	* enum AVCodecID id = av_codec_get_id(table, tag);
2172	* @endcode
2173	*/
2174	/**
2175	* @return the table mapping RIFF FourCCs for video to libavcodec AVCodecID.
2176	*/
2177	const struct AVCodecTag *avformat_get_riff_video_tags(void);
2178	/**
2179	* @return the table mapping RIFF FourCCs for audio to AVCodecID.
2180	*/
2181	const struct AVCodecTag *avformat_get_riff_audio_tags(void);
2182
2183	/**
2184	* @}
2185	*/
2186
2187	/**
2188	* Guess the sample aspect ratio of a frame, based on both the stream and the
2189	* frame aspect ratio.
2190	*
2191	* Since the frame aspect ratio is set by the codec but the stream aspect ratio
2192	* is set by the demuxer, these two may not be equal. This function tries to
2193	* return the value that you should use if you would like to display the frame.
2194	*
2195	* Basic logic is to use the stream aspect ratio if it is set to something sane
2196	* otherwise use the frame aspect ratio. This way a container setting, which is
2197	* usually easy to modify can override the coded value in the frames.
2198	*
2199	* @param format the format context which the stream is part of
2200	* @param stream the stream which the frame is part of
2201	* @param frame the frame with the aspect ratio to be determined
2202	* @return the guessed (valid) sample_aspect_ratio, 0/1 if no idea
2203	*/
2204	AVRational av_guess_sample_aspect_ratio(AVFormatContext *format, AVStream *stream, AVFrame *frame);
2205
2206	/**
2207	* Guess the frame rate, based on both the container and codec information.
2208	*
2209	* @param ctx the format context which the stream is part of
2210	* @param stream the stream which the frame is part of
2211	* @param frame the frame for which the frame rate should be determined, may be NULL
2212	* @return the guessed (valid) frame rate, 0/1 if no idea
2213	*/
2214	AVRational av_guess_frame_rate(AVFormatContext *ctx, AVStream *stream, AVFrame *frame);
2215
2216	/**
2217	* Check if the stream st contained in s is matched by the stream specifier
2218	* spec.
2219	*
2220	* See the "stream specifiers" chapter in the documentation for the syntax
2221	* of spec.
2222	*
2223	* @return >0 if st is matched by spec;
2224	* 0 if st is not matched by spec;
2225	* AVERROR code if spec is invalid
2226	*
2227	* @note A stream specifier can match several streams in the format.
2228	*/
2229	int avformat_match_stream_specifier(AVFormatContext *s, AVStream *st,
2230	const char *spec);
2231
2232	int avformat_queue_attached_pictures(AVFormatContext *s);
2233
2234
2235	/**
2236	* @}
2237	*/
2238
2239	#endif /* AVFORMAT_AVFORMAT_H */
2240