3 * Copyright (c) 2014 Benoit Fouet
5 * This file is part of FFmpeg.
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.
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.
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
25 * @see https://wiki.mozilla.org/APNG_Specification
26 * @see http://www.w3.org/TR/PNG
30 #include "avio_internal.h"
32 #include "libavutil/imgutils.h"
33 #include "libavutil/intreadwrite.h"
34 #include "libavutil/opt.h"
35 #include "libavcodec/png.h"
36 #include "libavcodec/bytestream.h"
38 #define DEFAULT_APNG_FPS 15
40 typedef struct APNGDemuxContext {
58 * To be a valid APNG file, we mandate, in this order:
66 static int apng_probe(AVProbeData *p)
72 bytestream2_init(&gb, p->buf, p->buf_size);
74 if (bytestream2_get_be64(&gb) != PNGSIG)
78 len = bytestream2_get_be32(&gb);
82 tag = bytestream2_get_le32(&gb);
83 /* we don't check IDAT size, as this is the last tag
84 * we check, and it may be larger than the probe buffer */
85 if (tag != MKTAG('I', 'D', 'A', 'T') &&
86 len > bytestream2_get_bytes_left(&gb))
90 case MKTAG('I', 'H', 'D', 'R'):
93 if (av_image_check_size(bytestream2_get_be32(&gb), bytestream2_get_be32(&gb), 0, NULL))
95 bytestream2_skip(&gb, 9);
98 case MKTAG('a', 'c', 'T', 'L'):
101 bytestream2_get_be32(&gb) == 0) /* 0 is not a valid value for number of frames */
103 bytestream2_skip(&gb, 8);
106 case MKTAG('I', 'D', 'A', 'T'):
111 /* skip other tags */
112 bytestream2_skip(&gb, len + 4);
118 return AVPROBE_SCORE_MAX;
121 static int append_extradata(AVCodecContext *s, AVIOContext *pb, int len)
123 int previous_size = s->extradata_size;
125 uint8_t *new_extradata;
127 if (previous_size > INT_MAX - len)
128 return AVERROR_INVALIDDATA;
130 new_size = previous_size + len;
131 new_extradata = av_realloc(s->extradata, new_size + FF_INPUT_BUFFER_PADDING_SIZE);
133 return AVERROR(ENOMEM);
134 s->extradata = new_extradata;
135 s->extradata_size = new_size;
137 if ((ret = avio_read(pb, s->extradata + previous_size, len)) < 0)
140 return previous_size;
143 static int apng_read_header(AVFormatContext *s)
145 APNGDemuxContext *ctx = s->priv_data;
146 AVIOContext *pb = s->pb;
149 int ret = AVERROR_INVALIDDATA, acTL_found = 0;
152 if (avio_rb64(pb) != PNGSIG)
155 /* parse IHDR (must be first chunk) */
158 if (len != 13 || tag != MKTAG('I', 'H', 'D', 'R'))
161 st = avformat_new_stream(s, NULL);
163 return AVERROR(ENOMEM);
165 st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
166 st->codec->codec_id = AV_CODEC_ID_APNG;
167 st->codec->width = avio_rb32(pb);
168 st->codec->height = avio_rb32(pb);
169 if ((ret = av_image_check_size(st->codec->width, st->codec->height, 0, s)) < 0)
172 /* extradata will contain every chunk up to the first fcTL (excluded) */
173 st->codec->extradata = av_malloc(len + 12 + FF_INPUT_BUFFER_PADDING_SIZE);
174 if (!st->codec->extradata)
175 return AVERROR(ENOMEM);
176 st->codec->extradata_size = len + 12;
177 AV_WB32(st->codec->extradata, len);
178 AV_WL32(st->codec->extradata+4, tag);
179 AV_WB32(st->codec->extradata+8, st->codec->width);
180 AV_WB32(st->codec->extradata+12, st->codec->height);
181 if ((ret = avio_read(pb, st->codec->extradata+16, 9)) < 0)
184 while (!avio_feof(pb)) {
185 if (acTL_found && ctx->num_play != 1) {
186 int64_t size = avio_size(pb);
187 int64_t offset = avio_tell(pb);
191 } else if (offset < 0) {
194 } else if ((ret = ffio_ensure_seekback(pb, size - offset)) < 0) {
195 av_log(s, AV_LOG_WARNING, "Could not ensure seekback, will not loop\n");
199 if ((ctx->num_play == 1 || !acTL_found) &&
200 ((ret = ffio_ensure_seekback(pb, 4 /* len */ + 4 /* tag */)) < 0))
204 if (len > 0x7fffffff) {
205 ret = AVERROR_INVALIDDATA;
211 case MKTAG('a', 'c', 'T', 'L'):
212 if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0 ||
213 (ret = append_extradata(st->codec, pb, len + 12)) < 0)
216 ctx->num_frames = AV_RB32(st->codec->extradata + ret + 8);
217 ctx->num_play = AV_RB32(st->codec->extradata + ret + 12);
218 av_log(s, AV_LOG_DEBUG, "num_frames: %"PRIu32", num_play: %"PRIu32"\n",
219 ctx->num_frames, ctx->num_play);
221 case MKTAG('f', 'c', 'T', 'L'):
223 ret = AVERROR_INVALIDDATA;
226 if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0)
230 if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0 ||
231 (ret = append_extradata(st->codec, pb, len + 12)) < 0)
237 if (st->codec->extradata_size) {
238 av_freep(&st->codec->extradata);
239 st->codec->extradata_size = 0;
244 static int decode_fctl_chunk(AVFormatContext *s, APNGDemuxContext *ctx, AVPacket *pkt)
246 uint32_t sequence_number, width, height, x_offset, y_offset;
247 uint16_t delay_num, delay_den;
248 uint8_t dispose_op, blend_op;
250 sequence_number = avio_rb32(s->pb);
251 width = avio_rb32(s->pb);
252 height = avio_rb32(s->pb);
253 x_offset = avio_rb32(s->pb);
254 y_offset = avio_rb32(s->pb);
255 delay_num = avio_rb16(s->pb);
256 delay_den = avio_rb16(s->pb);
257 dispose_op = avio_r8(s->pb);
258 blend_op = avio_r8(s->pb);
259 avio_skip(s->pb, 4); /* crc */
261 /* default is hundredths of seconds */
264 if (!delay_num || delay_den / delay_num > ctx->max_fps) {
266 delay_den = ctx->default_fps;
268 s->streams[0]->r_frame_rate.num = delay_den;
269 s->streams[0]->r_frame_rate.den = delay_num;
272 av_log(s, AV_LOG_DEBUG, "%s: "
273 "sequence_number: %"PRId32", "
275 "height: %"PRIu32", "
276 "x_offset: %"PRIu32", "
277 "y_offset: %"PRIu32", "
278 "delay_num: %"PRIu16", "
279 "delay_den: %"PRIu16", "
293 if (width != s->streams[0]->codec->width ||
294 height != s->streams[0]->codec->height ||
297 if (sequence_number == 0)
298 return AVERROR_INVALIDDATA;
299 ctx->is_key_frame = 0;
301 ctx->is_key_frame = 1;
307 static int apng_read_packet(AVFormatContext *s, AVPacket *pkt)
309 APNGDemuxContext *ctx = s->priv_data;
312 AVIOContext *pb = s->pb;
316 * fcTL chunk length, in bytes:
323 * 4 (tag (must be fdAT or IDAT))
325 /* if num_play is not 1, then the seekback is already guaranteed */
326 if (ctx->num_play == 1 && (ret = ffio_ensure_seekback(pb, 46)) < 0)
332 case MKTAG('f', 'c', 'T', 'L'):
334 return AVERROR_INVALIDDATA;
336 if ((ret = decode_fctl_chunk(s, ctx, pkt)) < 0)
339 /* fcTL must precede fdAT or IDAT */
342 if (len > 0x7fffffff ||
343 tag != MKTAG('f', 'd', 'A', 'T') &&
344 tag != MKTAG('I', 'D', 'A', 'T'))
345 return AVERROR_INVALIDDATA;
347 size = 38 /* fcTL */ + 8 /* len, tag */ + len + 4 /* crc */;
349 return AVERROR(EINVAL);
351 if ((ret = avio_seek(pb, -46, SEEK_CUR)) < 0 ||
352 (ret = av_append_packet(pb, pkt, size)) < 0)
355 if (ctx->num_play == 1 && (ret = ffio_ensure_seekback(pb, 8)) < 0)
361 tag != MKTAG('f', 'c', 'T', 'L') &&
362 tag != MKTAG('I', 'E', 'N', 'D')) {
363 if (len > 0x7fffffff)
364 return AVERROR_INVALIDDATA;
365 if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0 ||
366 (ret = av_append_packet(pb, pkt, len + 12)) < 0)
368 if (ctx->num_play == 1 && (ret = ffio_ensure_seekback(pb, 8)) < 0)
373 if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0)
376 if (ctx->is_key_frame)
377 pkt->flags |= AV_PKT_FLAG_KEY;
379 case MKTAG('I', 'E', 'N', 'D'):
381 if (ctx->ignore_loop || ctx->num_play >= 1 && ctx->cur_loop == ctx->num_play) {
382 avio_seek(pb, -8, SEEK_CUR);
385 if ((ret = avio_seek(pb, s->streams[0]->codec->extradata_size + 8, SEEK_SET)) < 0)
392 av_get_codec_tag_string(tag_buf, sizeof(tag_buf), tag);
393 avpriv_request_sample(s, "In-stream tag=%s (0x%08X) len=%"PRIu32, tag_buf, tag, len);
394 avio_skip(pb, len + 4);
398 /* Handle the unsupported yet cases */
399 return AVERROR_PATCHWELCOME;
402 static const AVOption options[] = {
403 { "ignore_loop", "ignore loop setting" , offsetof(APNGDemuxContext, ignore_loop),
404 AV_OPT_TYPE_INT, { .i64 = 1 } , 0, 1 , AV_OPT_FLAG_DECODING_PARAM },
405 { "max_fps" , "maximum framerate (0 is no limit)" , offsetof(APNGDemuxContext, max_fps),
406 AV_OPT_TYPE_INT, { .i64 = DEFAULT_APNG_FPS }, 0, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
407 { "default_fps", "default framerate (0 is as fast as possible)", offsetof(APNGDemuxContext, default_fps),
408 AV_OPT_TYPE_INT, { .i64 = DEFAULT_APNG_FPS }, 0, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
412 static const AVClass demuxer_class = {
413 .class_name = "APNG demuxer",
414 .item_name = av_default_item_name,
416 .version = LIBAVUTIL_VERSION_INT,
417 .category = AV_CLASS_CATEGORY_DEMUXER,
420 AVInputFormat ff_apng_demuxer = {
422 .long_name = NULL_IF_CONFIG_SMALL("Animated Portable Network Graphics"),
423 .priv_data_size = sizeof(APNGDemuxContext),
424 .read_probe = apng_probe,
425 .read_header = apng_read_header,
426 .read_packet = apng_read_packet,
427 .flags = AVFMT_GENERIC_INDEX,
428 .priv_class = &demuxer_class,