/*
* APNG demuxer
* Copyright (c) 2014 Benoit Fouet
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* APNG demuxer.
* @see https://wiki.mozilla.org/APNG_Specification
* @see http://www.w3.org/TR/PNG
*/
#include "avformat.h"
#include "avio_internal.h"
#include "internal.h"
#include "libavutil/imgutils.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/opt.h"
#include "libavcodec/apng.h"
#include "libavcodec/png.h"
#include "libavcodec/bytestream.h"
#define DEFAULT_APNG_FPS 15
typedef struct APNGDemuxContext {
const AVClass *class;
int max_fps;
int default_fps;
int64_t pkt_pts;
int pkt_duration;
int is_key_frame;
/*
* loop options
*/
int ignore_loop;
uint32_t num_frames;
uint32_t num_play;
uint32_t cur_loop;
} APNGDemuxContext;
/*
* To be a valid APNG file, we mandate, in this order:
* PNGSIG
* IHDR
* ...
* acTL
* ...
* IDAT
*/
static int apng_probe(AVProbeData *p)
{
GetByteContext gb;
int state = 0;
uint32_t len, tag;
bytestream2_init(&gb, p->buf, p->buf_size);
if (bytestream2_get_be64(&gb) != PNGSIG)
return 0;
for (;;) {
len = bytestream2_get_be32(&gb);
if (len > 0x7fffffff)
return 0;
tag = bytestream2_get_le32(&gb);
/* we don't check IDAT size, as this is the last tag
* we check, and it may be larger than the probe buffer */
if (tag != MKTAG('I', 'D', 'A', 'T') &&
len + 4 > bytestream2_get_bytes_left(&gb))
return 0;
switch (tag) {
case MKTAG('I', 'H', 'D', 'R'):
if (len != 13)
return 0;
if (av_image_check_size(bytestream2_get_be32(&gb), bytestream2_get_be32(&gb), 0, NULL))
return 0;
bytestream2_skip(&gb, 9);
state++;
break;
case MKTAG('a', 'c', 'T', 'L'):
if (state != 1 ||
len != 8 ||
bytestream2_get_be32(&gb) == 0) /* 0 is not a valid value for number of frames */
return 0;
bytestream2_skip(&gb, 8);
state++;
break;
case MKTAG('I', 'D', 'A', 'T'):
if (state != 2)
return 0;
goto end;
default:
/* skip other tags */
bytestream2_skip(&gb, len + 4);
break;
}
}
end:
return AVPROBE_SCORE_MAX;
}
static int append_extradata(AVCodecContext *s, AVIOContext *pb, int len)
{
int previous_size = s->extradata_size;
int new_size, ret;
uint8_t *new_extradata;
if (previous_size > INT_MAX - len)
return AVERROR_INVALIDDATA;
new_size = previous_size + len;
new_extradata = av_realloc(s->extradata, new_size + AV_INPUT_BUFFER_PADDING_SIZE);
if (!new_extradata)
return AVERROR(ENOMEM);
s->extradata = new_extradata;
s->extradata_size = new_size;
if ((ret = avio_read(pb, s->extradata + previous_size, len)) < 0)
return ret;
return previous_size;
}
static int apng_read_header(AVFormatContext *s)
{
APNGDemuxContext *ctx = s->priv_data;
AVIOContext *pb = s->pb;
uint32_t len, tag;
AVStream *st;
int acTL_found = 0;
int64_t ret = AVERROR_INVALIDDATA;
/* verify PNGSIG */
if (avio_rb64(pb) != PNGSIG)
return ret;
/* parse IHDR (must be first chunk) */
len = avio_rb32(pb);
tag = avio_rl32(pb);
if (len != 13 || tag != MKTAG('I', 'H', 'D', 'R'))
return ret;
st = avformat_new_stream(s, NULL);
if (!st)
return AVERROR(ENOMEM);
/* set the timebase to something large enough (1/100,000 of second)
* to hopefully cope with all sane frame durations */
avpriv_set_pts_info(st, 64, 1, 100000);
st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
st->codec->codec_id = AV_CODEC_ID_APNG;
st->codec->width = avio_rb32(pb);
st->codec->height = avio_rb32(pb);
if ((ret = av_image_check_size(st->codec->width, st->codec->height, 0, s)) < 0)
return ret;
/* extradata will contain every chunk up to the first fcTL (excluded) */
st->codec->extradata = av_malloc(len + 12 + AV_INPUT_BUFFER_PADDING_SIZE);
if (!st->codec->extradata)
return AVERROR(ENOMEM);
st->codec->extradata_size = len + 12;
AV_WB32(st->codec->extradata, len);
AV_WL32(st->codec->extradata+4, tag);
AV_WB32(st->codec->extradata+8, st->codec->width);
AV_WB32(st->codec->extradata+12, st->codec->height);
if ((ret = avio_read(pb, st->codec->extradata+16, 9)) < 0)
goto fail;
while (!avio_feof(pb)) {
if (acTL_found && ctx->num_play != 1) {
int64_t size = avio_size(pb);
int64_t offset = avio_tell(pb);
if (size < 0) {
ret = size;
goto fail;
} else if (offset < 0) {
ret = offset;
goto fail;
} else if ((ret = ffio_ensure_seekback(pb, size - offset)) < 0) {
av_log(s, AV_LOG_WARNING, "Could not ensure seekback, will not loop\n");
ctx->num_play = 1;
}
}
if ((ctx->num_play == 1 || !acTL_found) &&
((ret = ffio_ensure_seekback(pb, 4 /* len */ + 4 /* tag */)) < 0))
goto fail;
len = avio_rb32(pb);
if (len > 0x7fffffff) {
ret = AVERROR_INVALIDDATA;
goto fail;
}
tag = avio_rl32(pb);
switch (tag) {
case MKTAG('a', 'c', 'T', 'L'):
if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0 ||
(ret = append_extradata(st->codec, pb, len + 12)) < 0)
goto fail;
acTL_found = 1;
ctx->num_frames = AV_RB32(st->codec->extradata + ret + 8);
ctx->num_play = AV_RB32(st->codec->extradata + ret + 12);
av_log(s, AV_LOG_DEBUG, "num_frames: %"PRIu32", num_play: %"PRIu32"\n",
ctx->num_frames, ctx->num_play);
break;
case MKTAG('f', 'c', 'T', 'L'):
if (!acTL_found) {
ret = AVERROR_INVALIDDATA;
goto fail;
}
if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0)
goto fail;
return 0;
default:
if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0 ||
(ret = append_extradata(st->codec, pb, len + 12)) < 0)
goto fail;
}
}
fail:
if (st->codec->extradata_size) {
av_freep(&st->codec->extradata);
st->codec->extradata_size = 0;
}
return ret;
}
static int decode_fctl_chunk(AVFormatContext *s, APNGDemuxContext *ctx, AVPacket *pkt)
{
uint32_t sequence_number, width, height, x_offset, y_offset;
uint16_t delay_num, delay_den;
uint8_t dispose_op, blend_op;
sequence_number = avio_rb32(s->pb);
width = avio_rb32(s->pb);
height = avio_rb32(s->pb);
x_offset = avio_rb32(s->pb);
y_offset = avio_rb32(s->pb);
delay_num = avio_rb16(s->pb);
delay_den = avio_rb16(s->pb);
dispose_op = avio_r8(s->pb);
blend_op = avio_r8(s->pb);
avio_skip(s->pb, 4); /* crc */
/* default is hundredths of seconds */
if (!delay_den)
delay_den = 100;
if (!delay_num || delay_den / delay_num > ctx->max_fps) {
delay_num = 1;
delay_den = ctx->default_fps;
}
ctx->pkt_duration = av_rescale_q(delay_num,
(AVRational){ 1, delay_den },
s->streams[0]->time_base);
av_log(s, AV_LOG_DEBUG, "%s: "
"sequence_number: %"PRId32", "
"width: %"PRIu32", "
"height: %"PRIu32", "
"x_offset: %"PRIu32", "
"y_offset: %"PRIu32", "
"delay_num: %"PRIu16", "
"delay_den: %"PRIu16", "
"dispose_op: %d, "
"blend_op: %d\n",
__FUNCTION__,
sequence_number,
width,
height,
x_offset,
y_offset,
delay_num,
delay_den,
dispose_op,
blend_op);
if (width != s->streams[0]->codec->width ||
height != s->streams[0]->codec->height ||
x_offset != 0 ||
y_offset != 0) {
if (sequence_number == 0 ||
x_offset >= s->streams[0]->codec->width ||
width > s->streams[0]->codec->width - x_offset ||
y_offset >= s->streams[0]->codec->height ||
height > s->streams[0]->codec->height - y_offset)
return AVERROR_INVALIDDATA;
ctx->is_key_frame = 0;
} else {
if (sequence_number == 0 && dispose_op == APNG_DISPOSE_OP_PREVIOUS)
dispose_op = APNG_DISPOSE_OP_BACKGROUND;
ctx->is_key_frame = dispose_op == APNG_DISPOSE_OP_BACKGROUND ||
blend_op == APNG_BLEND_OP_SOURCE;
}
return 0;
}
static int apng_read_packet(AVFormatContext *s, AVPacket *pkt)
{
APNGDemuxContext *ctx = s->priv_data;
int64_t ret;
int64_t size;
AVIOContext *pb = s->pb;
uint32_t len, tag;
/*
* fcTL chunk length, in bytes:
* 4 (length)
* 4 (tag)
* 26 (actual chunk)
* 4 (crc) bytes
* and needed next:
* 4 (length)
* 4 (tag (must be fdAT or IDAT))
*/
/* if num_play is not 1, then the seekback is already guaranteed */
if (ctx->num_play == 1 && (ret = ffio_ensure_seekback(pb, 46)) < 0)
return ret;
len = avio_rb32(pb);
tag = avio_rl32(pb);
switch (tag) {
case MKTAG('f', 'c', 'T', 'L'):
if (len != 26)
return AVERROR_INVALIDDATA;
if ((ret = decode_fctl_chunk(s, ctx, pkt)) < 0)
return ret;
/* fcTL must precede fdAT or IDAT */
len = avio_rb32(pb);
tag = avio_rl32(pb);
if (len > 0x7fffffff ||
tag != MKTAG('f', 'd', 'A', 'T') &&
tag != MKTAG('I', 'D', 'A', 'T'))
return AVERROR_INVALIDDATA;
size = 38 /* fcTL */ + 8 /* len, tag */ + len + 4 /* crc */;
if (size > INT_MAX)
return AVERROR(EINVAL);
if ((ret = avio_seek(pb, -46, SEEK_CUR)) < 0 ||
(ret = av_append_packet(pb, pkt, size)) < 0)
return ret;
if (ctx->num_play == 1 && (ret = ffio_ensure_seekback(pb, 8)) < 0)
return ret;
len = avio_rb32(pb);
tag = avio_rl32(pb);
while (tag &&
tag != MKTAG('f', 'c', 'T', 'L') &&
tag != MKTAG('I', 'E', 'N', 'D')) {
if (len > 0x7fffffff)
return AVERROR_INVALIDDATA;
if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0 ||
(ret = av_append_packet(pb, pkt, len + 12)) < 0)
return ret;
if (ctx->num_play == 1 && (ret = ffio_ensure_seekback(pb, 8)) < 0)
return ret;
len = avio_rb32(pb);
tag = avio_rl32(pb);
}
if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0)
return ret;
if (ctx->is_key_frame)
pkt->flags |= AV_PKT_FLAG_KEY;
pkt->pts = ctx->pkt_pts;
pkt->duration = ctx->pkt_duration;
ctx->pkt_pts += ctx->pkt_duration;
return ret;
case MKTAG('I', 'E', 'N', 'D'):
ctx->cur_loop++;
if (ctx->ignore_loop || ctx->num_play >= 1 && ctx->cur_loop == ctx->num_play) {
avio_seek(pb, -8, SEEK_CUR);
return AVERROR_EOF;
}
if ((ret = avio_seek(pb, s->streams[0]->codec->extradata_size + 8, SEEK_SET)) < 0)
return ret;
return 0;
default:
{
char tag_buf[32];
av_get_codec_tag_string(tag_buf, sizeof(tag_buf), tag);
avpriv_request_sample(s, "In-stream tag=%s (0x%08X) len=%"PRIu32, tag_buf, tag, len);
avio_skip(pb, len + 4);
}
}
/* Handle the unsupported yet cases */
return AVERROR_PATCHWELCOME;
}
static const AVOption options[] = {
{ "ignore_loop", "ignore loop setting" , offsetof(APNGDemuxContext
, ignore_loop
), AV_OPT_TYPE_INT, { .i64 = 1 } , 0, 1 , AV_OPT_FLAG_DECODING_PARAM },
{ "max_fps" , "maximum framerate (0 is no limit)" , offsetof(APNGDemuxContext
, max_fps
), AV_OPT_TYPE_INT, { .i64 = DEFAULT_APNG_FPS }, 0, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
{ "default_fps", "default framerate (0 is as fast as possible)", offsetof(APNGDemuxContext
, default_fps
), AV_OPT_TYPE_INT, { .i64 = DEFAULT_APNG_FPS }, 0, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
{ NULL },
};
static const AVClass demuxer_class = {
.class_name = "APNG demuxer",
.item_name = av_default_item_name,
.option = options,
.version = LIBAVUTIL_VERSION_INT,
.category = AV_CLASS_CATEGORY_DEMUXER,
};
AVInputFormat ff_apng_demuxer = {
.name = "apng",
.long_name = NULL_IF_CONFIG_SMALL("Animated Portable Network Graphics"),
.priv_data_size = sizeof(APNGDemuxContext),
.read_probe = apng_probe,
.read_header = apng_read_header,
.read_packet = apng_read_packet,
.flags = AVFMT_GENERIC_INDEX,
.priv_class = &demuxer_class,
};