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path: root/libavformat/apngdec.c (plain)
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1/*
2 * APNG demuxer
3 * Copyright (c) 2014 Benoit Fouet
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22/**
23 * @file
24 * APNG demuxer.
25 * @see https://wiki.mozilla.org/APNG_Specification
26 * @see http://www.w3.org/TR/PNG
27 */
28
29#include "avformat.h"
30#include "avio_internal.h"
31#include "internal.h"
32#include "libavutil/imgutils.h"
33#include "libavutil/intreadwrite.h"
34#include "libavutil/opt.h"
35#include "libavcodec/apng.h"
36#include "libavcodec/png.h"
37#include "libavcodec/bytestream.h"
38
39#define DEFAULT_APNG_FPS 15
40
41typedef struct APNGDemuxContext {
42 const AVClass *class;
43
44 int max_fps;
45 int default_fps;
46
47 int64_t pkt_pts;
48 int pkt_duration;
49
50 int is_key_frame;
51
52 /*
53 * loop options
54 */
55 int ignore_loop;
56 uint32_t num_frames;
57 uint32_t num_play;
58 uint32_t cur_loop;
59} APNGDemuxContext;
60
61/*
62 * To be a valid APNG file, we mandate, in this order:
63 * PNGSIG
64 * IHDR
65 * ...
66 * acTL
67 * ...
68 * IDAT
69 */
70static int apng_probe(AVProbeData *p)
71{
72 GetByteContext gb;
73 int state = 0;
74 uint32_t len, tag;
75
76 bytestream2_init(&gb, p->buf, p->buf_size);
77
78 if (bytestream2_get_be64(&gb) != PNGSIG)
79 return 0;
80
81 for (;;) {
82 len = bytestream2_get_be32(&gb);
83 if (len > 0x7fffffff)
84 return 0;
85
86 tag = bytestream2_get_le32(&gb);
87 /* we don't check IDAT size, as this is the last tag
88 * we check, and it may be larger than the probe buffer */
89 if (tag != MKTAG('I', 'D', 'A', 'T') &&
90 len + 4 > bytestream2_get_bytes_left(&gb))
91 return 0;
92
93 switch (tag) {
94 case MKTAG('I', 'H', 'D', 'R'):
95 if (len != 13)
96 return 0;
97 if (av_image_check_size(bytestream2_get_be32(&gb), bytestream2_get_be32(&gb), 0, NULL))
98 return 0;
99 bytestream2_skip(&gb, 9);
100 state++;
101 break;
102 case MKTAG('a', 'c', 'T', 'L'):
103 if (state != 1 ||
104 len != 8 ||
105 bytestream2_get_be32(&gb) == 0) /* 0 is not a valid value for number of frames */
106 return 0;
107 bytestream2_skip(&gb, 8);
108 state++;
109 break;
110 case MKTAG('I', 'D', 'A', 'T'):
111 if (state != 2)
112 return 0;
113 goto end;
114 default:
115 /* skip other tags */
116 bytestream2_skip(&gb, len + 4);
117 break;
118 }
119 }
120
121end:
122 return AVPROBE_SCORE_MAX;
123}
124
125static int append_extradata(AVCodecParameters *par, AVIOContext *pb, int len)
126{
127 int previous_size = par->extradata_size;
128 int new_size, ret;
129 uint8_t *new_extradata;
130
131 if (previous_size > INT_MAX - len)
132 return AVERROR_INVALIDDATA;
133
134 new_size = previous_size + len;
135 new_extradata = av_realloc(par->extradata, new_size + AV_INPUT_BUFFER_PADDING_SIZE);
136 if (!new_extradata)
137 return AVERROR(ENOMEM);
138 par->extradata = new_extradata;
139 par->extradata_size = new_size;
140
141 if ((ret = avio_read(pb, par->extradata + previous_size, len)) < 0)
142 return ret;
143
144 return previous_size;
145}
146
147static int apng_read_header(AVFormatContext *s)
148{
149 APNGDemuxContext *ctx = s->priv_data;
150 AVIOContext *pb = s->pb;
151 uint32_t len, tag;
152 AVStream *st;
153 int acTL_found = 0;
154 int64_t ret = AVERROR_INVALIDDATA;
155
156 /* verify PNGSIG */
157 if (avio_rb64(pb) != PNGSIG)
158 return ret;
159
160 /* parse IHDR (must be first chunk) */
161 len = avio_rb32(pb);
162 tag = avio_rl32(pb);
163 if (len != 13 || tag != MKTAG('I', 'H', 'D', 'R'))
164 return ret;
165
166 st = avformat_new_stream(s, NULL);
167 if (!st)
168 return AVERROR(ENOMEM);
169
170 /* set the timebase to something large enough (1/100,000 of second)
171 * to hopefully cope with all sane frame durations */
172 avpriv_set_pts_info(st, 64, 1, 100000);
173 st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
174 st->codecpar->codec_id = AV_CODEC_ID_APNG;
175 st->codecpar->width = avio_rb32(pb);
176 st->codecpar->height = avio_rb32(pb);
177 if ((ret = av_image_check_size(st->codecpar->width, st->codecpar->height, 0, s)) < 0)
178 return ret;
179
180 /* extradata will contain every chunk up to the first fcTL (excluded) */
181 st->codecpar->extradata = av_malloc(len + 12 + AV_INPUT_BUFFER_PADDING_SIZE);
182 if (!st->codecpar->extradata)
183 return AVERROR(ENOMEM);
184 st->codecpar->extradata_size = len + 12;
185 AV_WB32(st->codecpar->extradata, len);
186 AV_WL32(st->codecpar->extradata+4, tag);
187 AV_WB32(st->codecpar->extradata+8, st->codecpar->width);
188 AV_WB32(st->codecpar->extradata+12, st->codecpar->height);
189 if ((ret = avio_read(pb, st->codecpar->extradata+16, 9)) < 0)
190 goto fail;
191
192 while (!avio_feof(pb)) {
193 if (acTL_found && ctx->num_play != 1) {
194 int64_t size = avio_size(pb);
195 int64_t offset = avio_tell(pb);
196 if (size < 0) {
197 ret = size;
198 goto fail;
199 } else if (offset < 0) {
200 ret = offset;
201 goto fail;
202 } else if ((ret = ffio_ensure_seekback(pb, size - offset)) < 0) {
203 av_log(s, AV_LOG_WARNING, "Could not ensure seekback, will not loop\n");
204 ctx->num_play = 1;
205 }
206 }
207 if ((ctx->num_play == 1 || !acTL_found) &&
208 ((ret = ffio_ensure_seekback(pb, 4 /* len */ + 4 /* tag */)) < 0))
209 goto fail;
210
211 len = avio_rb32(pb);
212 if (len > 0x7fffffff) {
213 ret = AVERROR_INVALIDDATA;
214 goto fail;
215 }
216
217 tag = avio_rl32(pb);
218 switch (tag) {
219 case MKTAG('a', 'c', 'T', 'L'):
220 if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0 ||
221 (ret = append_extradata(st->codecpar, pb, len + 12)) < 0)
222 goto fail;
223 acTL_found = 1;
224 ctx->num_frames = AV_RB32(st->codecpar->extradata + ret + 8);
225 ctx->num_play = AV_RB32(st->codecpar->extradata + ret + 12);
226 av_log(s, AV_LOG_DEBUG, "num_frames: %"PRIu32", num_play: %"PRIu32"\n",
227 ctx->num_frames, ctx->num_play);
228 break;
229 case MKTAG('f', 'c', 'T', 'L'):
230 if (!acTL_found) {
231 ret = AVERROR_INVALIDDATA;
232 goto fail;
233 }
234 if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0)
235 goto fail;
236 return 0;
237 default:
238 if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0 ||
239 (ret = append_extradata(st->codecpar, pb, len + 12)) < 0)
240 goto fail;
241 }
242 }
243
244fail:
245 if (st->codecpar->extradata_size) {
246 av_freep(&st->codecpar->extradata);
247 st->codecpar->extradata_size = 0;
248 }
249 return ret;
250}
251
252static int decode_fctl_chunk(AVFormatContext *s, APNGDemuxContext *ctx, AVPacket *pkt)
253{
254 uint32_t sequence_number, width, height, x_offset, y_offset;
255 uint16_t delay_num, delay_den;
256 uint8_t dispose_op, blend_op;
257
258 sequence_number = avio_rb32(s->pb);
259 width = avio_rb32(s->pb);
260 height = avio_rb32(s->pb);
261 x_offset = avio_rb32(s->pb);
262 y_offset = avio_rb32(s->pb);
263 delay_num = avio_rb16(s->pb);
264 delay_den = avio_rb16(s->pb);
265 dispose_op = avio_r8(s->pb);
266 blend_op = avio_r8(s->pb);
267 avio_skip(s->pb, 4); /* crc */
268
269 /* default is hundredths of seconds */
270 if (!delay_den)
271 delay_den = 100;
272 if (!delay_num || (ctx->max_fps && delay_den / delay_num > ctx->max_fps)) {
273 delay_num = 1;
274 delay_den = ctx->default_fps;
275 }
276 ctx->pkt_duration = av_rescale_q(delay_num,
277 (AVRational){ 1, delay_den },
278 s->streams[0]->time_base);
279
280 av_log(s, AV_LOG_DEBUG, "%s: "
281 "sequence_number: %"PRId32", "
282 "width: %"PRIu32", "
283 "height: %"PRIu32", "
284 "x_offset: %"PRIu32", "
285 "y_offset: %"PRIu32", "
286 "delay_num: %"PRIu16", "
287 "delay_den: %"PRIu16", "
288 "dispose_op: %d, "
289 "blend_op: %d\n",
290 __FUNCTION__,
291 sequence_number,
292 width,
293 height,
294 x_offset,
295 y_offset,
296 delay_num,
297 delay_den,
298 dispose_op,
299 blend_op);
300
301 if (width != s->streams[0]->codecpar->width ||
302 height != s->streams[0]->codecpar->height ||
303 x_offset != 0 ||
304 y_offset != 0) {
305 if (sequence_number == 0 ||
306 x_offset >= s->streams[0]->codecpar->width ||
307 width > s->streams[0]->codecpar->width - x_offset ||
308 y_offset >= s->streams[0]->codecpar->height ||
309 height > s->streams[0]->codecpar->height - y_offset)
310 return AVERROR_INVALIDDATA;
311 ctx->is_key_frame = 0;
312 } else {
313 if (sequence_number == 0 && dispose_op == APNG_DISPOSE_OP_PREVIOUS)
314 dispose_op = APNG_DISPOSE_OP_BACKGROUND;
315 ctx->is_key_frame = dispose_op == APNG_DISPOSE_OP_BACKGROUND ||
316 blend_op == APNG_BLEND_OP_SOURCE;
317 }
318
319 return 0;
320}
321
322static int apng_read_packet(AVFormatContext *s, AVPacket *pkt)
323{
324 APNGDemuxContext *ctx = s->priv_data;
325 int64_t ret;
326 int64_t size;
327 AVIOContext *pb = s->pb;
328 uint32_t len, tag;
329
330 /*
331 * fcTL chunk length, in bytes:
332 * 4 (length)
333 * 4 (tag)
334 * 26 (actual chunk)
335 * 4 (crc) bytes
336 * and needed next:
337 * 4 (length)
338 * 4 (tag (must be fdAT or IDAT))
339 */
340 /* if num_play is not 1, then the seekback is already guaranteed */
341 if (ctx->num_play == 1 && (ret = ffio_ensure_seekback(pb, 46)) < 0)
342 return ret;
343
344 len = avio_rb32(pb);
345 tag = avio_rl32(pb);
346 switch (tag) {
347 case MKTAG('f', 'c', 'T', 'L'):
348 if (len != 26)
349 return AVERROR_INVALIDDATA;
350
351 if ((ret = decode_fctl_chunk(s, ctx, pkt)) < 0)
352 return ret;
353
354 /* fcTL must precede fdAT or IDAT */
355 len = avio_rb32(pb);
356 tag = avio_rl32(pb);
357 if (len > 0x7fffffff ||
358 tag != MKTAG('f', 'd', 'A', 'T') &&
359 tag != MKTAG('I', 'D', 'A', 'T'))
360 return AVERROR_INVALIDDATA;
361
362 size = 38 /* fcTL */ + 8 /* len, tag */ + len + 4 /* crc */;
363 if (size > INT_MAX)
364 return AVERROR(EINVAL);
365
366 if ((ret = avio_seek(pb, -46, SEEK_CUR)) < 0 ||
367 (ret = av_append_packet(pb, pkt, size)) < 0)
368 return ret;
369
370 if (ctx->num_play == 1 && (ret = ffio_ensure_seekback(pb, 8)) < 0)
371 return ret;
372
373 len = avio_rb32(pb);
374 tag = avio_rl32(pb);
375 while (tag &&
376 tag != MKTAG('f', 'c', 'T', 'L') &&
377 tag != MKTAG('I', 'E', 'N', 'D')) {
378 if (len > 0x7fffffff)
379 return AVERROR_INVALIDDATA;
380 if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0 ||
381 (ret = av_append_packet(pb, pkt, len + 12)) < 0)
382 return ret;
383 if (ctx->num_play == 1 && (ret = ffio_ensure_seekback(pb, 8)) < 0)
384 return ret;
385 len = avio_rb32(pb);
386 tag = avio_rl32(pb);
387 }
388 if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0)
389 return ret;
390
391 if (ctx->is_key_frame)
392 pkt->flags |= AV_PKT_FLAG_KEY;
393 pkt->pts = ctx->pkt_pts;
394 pkt->duration = ctx->pkt_duration;
395 ctx->pkt_pts += ctx->pkt_duration;
396 return ret;
397 case MKTAG('I', 'E', 'N', 'D'):
398 ctx->cur_loop++;
399 if (ctx->ignore_loop || ctx->num_play >= 1 && ctx->cur_loop == ctx->num_play) {
400 avio_seek(pb, -8, SEEK_CUR);
401 return AVERROR_EOF;
402 }
403 if ((ret = avio_seek(pb, s->streams[0]->codecpar->extradata_size + 8, SEEK_SET)) < 0)
404 return ret;
405 return 0;
406 default:
407 avpriv_request_sample(s, "In-stream tag=%s (0x%08"PRIX32") len=%"PRIu32,
408 av_fourcc2str(tag), tag, len);
409 avio_skip(pb, len + 4);
410 }
411
412 /* Handle the unsupported yet cases */
413 return AVERROR_PATCHWELCOME;
414}
415
416static const AVOption options[] = {
417 { "ignore_loop", "ignore loop setting" , offsetof(APNGDemuxContext, ignore_loop),
418 AV_OPT_TYPE_BOOL, { .i64 = 1 } , 0, 1 , AV_OPT_FLAG_DECODING_PARAM },
419 { "max_fps" , "maximum framerate (0 is no limit)" , offsetof(APNGDemuxContext, max_fps),
420 AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
421 { "default_fps", "default framerate (0 is as fast as possible)", offsetof(APNGDemuxContext, default_fps),
422 AV_OPT_TYPE_INT, { .i64 = DEFAULT_APNG_FPS }, 0, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
423 { NULL },
424};
425
426static const AVClass demuxer_class = {
427 .class_name = "APNG demuxer",
428 .item_name = av_default_item_name,
429 .option = options,
430 .version = LIBAVUTIL_VERSION_INT,
431 .category = AV_CLASS_CATEGORY_DEMUXER,
432};
433
434AVInputFormat ff_apng_demuxer = {
435 .name = "apng",
436 .long_name = NULL_IF_CONFIG_SMALL("Animated Portable Network Graphics"),
437 .priv_data_size = sizeof(APNGDemuxContext),
438 .read_probe = apng_probe,
439 .read_header = apng_read_header,
440 .read_packet = apng_read_packet,
441 .flags = AVFMT_GENERIC_INDEX,
442 .priv_class = &demuxer_class,
443};
444
generated by cgit at 2024-05-17 20:22:42 (GMT)