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
28 * Not supported (yet):
29 * - streams with chunks other than fcTL / fdAT / IEND after the first fcTL
30 * - streams with multiple fdAT chunks after an fcTL one
34 #include "avio_internal.h"
36 #include "libavutil/imgutils.h"
37 #include "libavutil/intreadwrite.h"
38 #include "libavutil/opt.h"
39 #include "libavcodec/png.h"
40 #include "libavcodec/bytestream.h"
42 #define DEFAULT_APNG_FPS 15
44 typedef struct APNGDemuxContext {
62 * To be a valid APNG file, we mandate, in this order:
70 static int apng_probe(AVProbeData *p)
76 bytestream2_init(&gb, p->buf, p->buf_size);
78 if (bytestream2_get_be64(&gb) != PNGSIG)
82 len = bytestream2_get_be32(&gb);
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 > bytestream2_get_bytes_left(&gb))
94 case MKTAG('I', 'H', 'D', 'R'):
97 if (av_image_check_size(bytestream2_get_be32(&gb), bytestream2_get_be32(&gb), 0, NULL))
99 bytestream2_skip(&gb, 9);
102 case MKTAG('a', 'c', 'T', 'L'):
105 bytestream2_get_be32(&gb) == 0) /* 0 is not a valid value for number of frames */
107 bytestream2_skip(&gb, 8);
110 case MKTAG('I', 'D', 'A', 'T'):
115 /* skip other tags */
116 bytestream2_skip(&gb, len + 4);
122 return AVPROBE_SCORE_MAX;
125 static int append_extradata(AVCodecContext *s, AVIOContext *pb, int len)
127 int previous_size = s->extradata_size;
129 uint8_t *new_extradata;
131 if (previous_size > INT_MAX - len)
132 return AVERROR_INVALIDDATA;
134 new_size = previous_size + len;
135 new_extradata = av_realloc(s->extradata, new_size + FF_INPUT_BUFFER_PADDING_SIZE);
137 return AVERROR(ENOMEM);
138 s->extradata = new_extradata;
139 s->extradata_size = new_size;
141 if ((ret = avio_read(pb, s->extradata + previous_size, len)) < 0)
144 return previous_size;
147 static int apng_read_header(AVFormatContext *s)
149 APNGDemuxContext *ctx = s->priv_data;
150 AVIOContext *pb = s->pb;
153 int ret = AVERROR_INVALIDDATA, acTL_found = 0;
156 if (avio_rb64(pb) != PNGSIG)
159 /* parse IHDR (must be first chunk) */
162 if (len != 13 || tag != MKTAG('I', 'H', 'D', 'R'))
165 st = avformat_new_stream(s, NULL);
167 return AVERROR(ENOMEM);
169 st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
170 st->codec->codec_id = AV_CODEC_ID_APNG;
171 st->codec->width = avio_rb32(pb);
172 st->codec->height = avio_rb32(pb);
173 if ((ret = av_image_check_size(st->codec->width, st->codec->height, 0, s)) < 0)
176 /* extradata will contain every chunk up to the first fcTL (excluded) */
177 st->codec->extradata = av_malloc(len + 12 + FF_INPUT_BUFFER_PADDING_SIZE);
178 if (!st->codec->extradata)
179 return AVERROR(ENOMEM);
180 st->codec->extradata_size = len + 12;
181 AV_WB32(st->codec->extradata, len);
182 AV_WL32(st->codec->extradata+4, tag);
183 AV_WB32(st->codec->extradata+8, st->codec->width);
184 AV_WB32(st->codec->extradata+12, st->codec->height);
185 if ((ret = avio_read(pb, st->codec->extradata+16, 9)) < 0)
188 while (!avio_feof(pb)) {
189 if (acTL_found && ctx->num_play != 1) {
190 int64_t size = avio_size(pb);
191 int64_t offset = avio_tell(pb);
195 } else if (offset < 0) {
198 } else if ((ret = ffio_ensure_seekback(pb, size - offset)) < 0) {
199 av_log(s, AV_LOG_WARNING, "Could not ensure seekback, will not loop\n");
203 if ((ctx->num_play == 1 || !acTL_found) &&
204 ((ret = ffio_ensure_seekback(pb, 4 /* len */ + 4 /* tag */)) < 0))
208 if (len > 0x7fffffff) {
209 ret = AVERROR_INVALIDDATA;
215 case MKTAG('a', 'c', 'T', 'L'):
216 if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0 ||
217 (ret = append_extradata(st->codec, pb, len + 12)) < 0)
220 ctx->num_frames = AV_RB32(st->codec->extradata + ret + 8);
221 ctx->num_play = AV_RB32(st->codec->extradata + ret + 12);
222 av_log(s, AV_LOG_DEBUG, "num_frames: %"PRIu32", num_play: %"PRIu32"\n",
223 ctx->num_frames, ctx->num_play);
225 case MKTAG('f', 'c', 'T', 'L'):
227 ret = AVERROR_INVALIDDATA;
230 if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0)
234 if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0 ||
235 (ret = append_extradata(st->codec, pb, len + 12)) < 0)
241 if (st->codec->extradata_size) {
242 av_freep(&st->codec->extradata);
243 st->codec->extradata_size = 0;
248 static int decode_fctl_chunk(AVFormatContext *s, APNGDemuxContext *ctx, AVPacket *pkt)
250 uint32_t sequence_number, width, height, x_offset, y_offset;
251 uint16_t delay_num, delay_den;
252 uint8_t dispose_op, blend_op;
254 sequence_number = avio_rb32(s->pb);
255 width = avio_rb32(s->pb);
256 height = avio_rb32(s->pb);
257 x_offset = avio_rb32(s->pb);
258 y_offset = avio_rb32(s->pb);
259 delay_num = avio_rb16(s->pb);
260 delay_den = avio_rb16(s->pb);
261 dispose_op = avio_r8(s->pb);
262 blend_op = avio_r8(s->pb);
263 avio_skip(s->pb, 4); /* crc */
265 /* default is hundredths of seconds */
268 if (!delay_num || delay_den / delay_num > ctx->max_fps) {
270 delay_den = ctx->default_fps;
272 s->streams[0]->r_frame_rate.num = delay_den;
273 s->streams[0]->r_frame_rate.den = delay_num;
276 av_log(s, AV_LOG_DEBUG, "%s: "
277 "sequence_number: %"PRId32", "
279 "height: %"PRIu32", "
280 "x_offset: %"PRIu32", "
281 "y_offset: %"PRIu32", "
282 "delay_num: %"PRIu16", "
283 "delay_den: %"PRIu16", "
297 if (width != s->streams[0]->codec->width ||
298 height != s->streams[0]->codec->height ||
301 if (sequence_number == 0)
302 return AVERROR_INVALIDDATA;
303 ctx->is_key_frame = 0;
305 ctx->is_key_frame = 1;
311 static int apng_read_packet(AVFormatContext *s, AVPacket *pkt)
313 APNGDemuxContext *ctx = s->priv_data;
316 AVIOContext *pb = s->pb;
320 * fcTL chunk length, in bytes:
327 * 4 (tag (must be fdAT or IDAT))
329 * TODO: support multiple fdAT following an fcTL
331 /* if num_play is not 1, then the seekback is already guaranteed */
332 if (ctx->num_play == 1 && (ret = ffio_ensure_seekback(pb, 46)) < 0)
338 case MKTAG('f', 'c', 'T', 'L'):
340 return AVERROR_INVALIDDATA;
342 if ((ret = decode_fctl_chunk(s, ctx, pkt)) < 0)
345 /* fcTL must precede fdAT or IDAT */
348 if (len > 0x7fffffff ||
349 tag != MKTAG('f', 'd', 'A', 'T') &&
350 tag != MKTAG('I', 'D', 'A', 'T'))
351 return AVERROR_INVALIDDATA;
353 if ((ret = avio_seek(pb, -46, SEEK_CUR)) < 0)
356 size = 38 /* fcTL */ + 8 /* len, tag */ + len + 4 /* crc */;
358 return AVERROR(EINVAL);
360 if ((ret = av_get_packet(pb, pkt, size)) < 0)
362 if (ctx->is_key_frame)
363 pkt->flags |= AV_PKT_FLAG_KEY;
365 case MKTAG('I', 'E', 'N', 'D'):
367 if (ctx->ignore_loop || ctx->num_play >= 1 && ctx->cur_loop == ctx->num_play) {
368 avio_seek(pb, -8, SEEK_CUR);
371 if ((ret = avio_seek(pb, s->streams[0]->codec->extradata_size + 8, SEEK_SET)) < 0)
378 av_get_codec_tag_string(tag_buf, sizeof(tag_buf), tag);
379 avpriv_request_sample(s, "In-stream tag=%s (0x%08X) len=%"PRIu32, tag_buf, tag, len);
380 avio_skip(pb, len + 4);
384 /* Handle the unsupported yet cases */
385 return AVERROR_PATCHWELCOME;
388 static const AVOption options[] = {
389 { "ignore_loop", "ignore loop setting" , offsetof(APNGDemuxContext, ignore_loop),
390 AV_OPT_TYPE_INT, { .i64 = 1 } , 0, 1 , AV_OPT_FLAG_DECODING_PARAM },
391 { "max_fps" , "maximum framerate (0 is no limit)" , offsetof(APNGDemuxContext, max_fps),
392 AV_OPT_TYPE_INT, { .i64 = DEFAULT_APNG_FPS }, 0, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
393 { "default_fps", "default framerate (0 is as fast as possible)", offsetof(APNGDemuxContext, default_fps),
394 AV_OPT_TYPE_INT, { .i64 = DEFAULT_APNG_FPS }, 0, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
398 static const AVClass demuxer_class = {
399 .class_name = "APNG demuxer",
400 .item_name = av_default_item_name,
402 .version = LIBAVUTIL_VERSION_INT,
403 .category = AV_CLASS_CATEGORY_DEMUXER,
406 AVInputFormat ff_apng_demuxer = {
408 .long_name = NULL_IF_CONFIG_SMALL("Animated Portable Network Graphics"),
409 .priv_data_size = sizeof(APNGDemuxContext),
410 .read_probe = apng_probe,
411 .read_header = apng_read_header,
412 .read_packet = apng_read_packet,
413 .flags = AVFMT_GENERIC_INDEX,
414 .priv_class = &demuxer_class,