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avformat/webp: add Animated WebP demuxer

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Original work by Josef Zlomek <josef@pex.com>

Signed-off-by: Ramiro Polla <ramiro.polla@gmail.com>
This commit is contained in:
Ramiro Polla committed 2026-05-19 11:36:10 +02:00
1 parent a3d8ba6613
commit 20b009e301
6 files changed
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Changelog
+1
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@@ -13,6 +13,7 @@ version <next>:
- ProRes RAW VideoToolbox hwaccel
- APV Vulkan hwaccel
- Animated WebP decoder
- Animated WebP demuxer
version 8.1:
doc/demuxers.texi
+35
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@@ -1187,4 +1187,39 @@ this is set to 0, which means that a sensible value is chosen based on the
input format.
@end table
@section webp
Animated WebP demuxer.
It accepts the following options:
@table @option
@item -min_delay @var{int}
Set the minimum valid delay between frames in milliseconds.
Range is 0 to 60000. Default value is 10.
@item -max_webp_delay @var{int}
Set the maximum valid delay between frames in milliseconds.
Range is 0 to 16777215. Default value is 16777215 (over four hours),
the maximum value allowed by the specification.
@item -default_delay @var{int}
Set the default delay between frames in milliseconds.
Range is 0 to 60000. Default value is 100.
@item -ignore_loop @var{bool}
WebP files can contain information to loop a certain number of times
(or infinitely). If @option{ignore_loop} is set to true, then the loop
setting from the input will be ignored and looping will not occur.
If set to false, then looping will occur and will cycle the number
of times according to the WebP. Default value is true.
@item usebgcolor @var{bool}
WebP files contain a background color hint in the ANIM chunk, but the
WebP specification says that viewer applications are not required to
use it. If @option{usebgcolor} is set to true, then the background
color hint will be used, otherwise transparent black will be used for
the background. Default value is false.
@end table
@c man end DEMUXERS
libavformat/Makefile
+1
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@@ -646,6 +646,7 @@ OBJS-$(CONFIG_WEBM_MUXER) += matroskaenc.o matroska.o \
avlanguage.o
OBJS-$(CONFIG_WEBM_DASH_MANIFEST_MUXER) += webmdashenc.o
OBJS-$(CONFIG_WEBM_CHUNK_MUXER) += webm_chunk.o
OBJS-$(CONFIG_WEBP_ANIM_DEMUXER) += webp_anim_dec.o
OBJS-$(CONFIG_WEBP_MUXER) += webpenc.o
OBJS-$(CONFIG_WEBVTT_DEMUXER) += webvttdec.o subtitles.o
OBJS-$(CONFIG_WEBVTT_MUXER) += webvttenc.o
libavformat/allformats.c
+1
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@@ -516,6 +516,7 @@ extern const FFInputFormat ff_webm_dash_manifest_demuxer;
extern const FFOutputFormat ff_webm_dash_manifest_muxer;
extern const FFOutputFormat ff_webm_chunk_muxer;
extern const FFOutputFormat ff_webp_muxer;
extern const FFInputFormat ff_webp_anim_demuxer;
extern const FFInputFormat ff_webvtt_demuxer;
extern const FFOutputFormat ff_webvtt_muxer;
extern const FFInputFormat ff_wsaud_demuxer;
libavformat/version.h
+1 -1
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@@ -31,7 +31,7 @@
#include "version_major.h"
#define LIBAVFORMAT_VERSION_MINOR 17
#define LIBAVFORMAT_VERSION_MINOR 18
#define LIBAVFORMAT_VERSION_MICRO 100
#define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
libavformat/webp_anim_dec.c
+371
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@@ -0,0 +1,371 @@
/*
* Animated WebP demuxer
* Copyright (c) 2020 Pexeso Inc.
* Copyright (c) 2026 Ramiro Polla
*
* 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
* Animated WebP demuxer.
*/
#include "avio_internal.h"
#include "demux.h"
#include "avformat.h"
#include "internal.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/mem.h"
#include "libavutil/opt.h"
#define VP8X_FLAG_ANIMATION 0x02
#define VP8X_FLAG_XMP_METADATA 0x04
#define VP8X_FLAG_EXIF_METADATA 0x08
#define VP8X_FLAG_ALPHA 0x10
#define VP8X_FLAG_ICC 0x20
typedef struct WebPAnimDemuxContext {
const AVClass *class;
/**
* Minimum allowed delay between frames in milliseconds.
* Values below this threshold are considered to be invalid
* and set to value of default_delay.
*/
int min_delay;
int max_delay;
int default_delay;
/*
* loop options
*/
int ignore_loop; ///< ignore loop setting
int loop_count; ///< number of times to loop the animation
int cur_loop; ///< current loop counter
/*
* variables for the key frame detection
*/
int cur_frame; ///< number of frames of the current animation file
int vp8x_flags;
int has_iccp;
int has_exif;
int has_anim;
int has_xmp;
int usebgcolor;
int64_t first_anmf_offset;
} WebPAnimDemuxContext;
/**
* Major web browsers display WebPs at ~10-15fps when rate is not
* explicitly set or have too low values. We assume default rate to be 10.
* Default delay = 1000 microseconds / 10fps = 100 milliseconds per frame.
*/
#define WEBP_DEFAULT_DELAY 100
/**
* By default delay values less than this threshold considered to be invalid.
*/
#define WEBP_MIN_DELAY 10
static int webp_anim_probe(const AVProbeData *p)
{
const uint8_t *b = p->buf;
if (AV_RL32(b) == MKTAG('R', 'I', 'F', 'F') &&
AV_RL32(b + 8) == MKTAG('W', 'E', 'B', 'P') &&
AV_RL32(b + 12) == MKTAG('V', 'P', '8', 'X') &&
AV_RL32(b + 16) == 10 &&
(b[20] & VP8X_FLAG_ANIMATION))
return AVPROBE_SCORE_MAX;
return 0;
}
static int webp_anim_read_header(AVFormatContext *s)
{
WebPAnimDemuxContext *ctx = s->priv_data;
AVIOContext *pb = s->pb;
int ret;
/* Check for signature. */
if (avio_rl32(pb) != MKTAG('R', 'I', 'F', 'F'))
return AVERROR_INVALIDDATA;
avio_skip(pb, 4); /* file size */
if (avio_rl32(pb) != MKTAG('W', 'E', 'B', 'P'))
return AVERROR_INVALIDDATA;
/* VP8X must be first chunk */
if (avio_rl32(pb) != MKTAG('V', 'P', '8', 'X') ||
avio_rl32(pb) != 10 /* chunk size */)
return AVERROR_INVALIDDATA;
ctx->vp8x_flags = avio_r8(pb);
if (!(ctx->vp8x_flags & VP8X_FLAG_ANIMATION))
return AVERROR_INVALIDDATA;
avio_skip(pb, 3);
AVStream *st = avformat_new_stream(s, NULL);
if (!st)
return AVERROR(ENOMEM);
avpriv_set_pts_info(st, 64, 1, 1000);
st->codecpar->format = AV_PIX_FMT_ARGB;
st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
st->codecpar->codec_id = AV_CODEC_ID_WEBP_ANIM;
st->codecpar->width = avio_rl24(pb) + 1;
st->codecpar->height = avio_rl24(pb) + 1;
st->start_time = 0;
int explode = (s->error_recognition & AV_EF_EXPLODE);
int loglevel = explode ? AV_LOG_ERROR : AV_LOG_WARNING;
while (1) {
int64_t offset = avio_tell(pb);
uint32_t fourcc = avio_rl32(pb);
uint32_t size = avio_rl32(pb);
av_log(s, AV_LOG_DEBUG, "Chunk %s of size %u at offset %" PRId64 "\n",
av_fourcc2str(fourcc), size, offset);
if (size == UINT32_MAX)
return AVERROR_INVALIDDATA;
size += size & 1;
if (avio_feof(pb))
break;
switch (fourcc) {
case MKTAG('I', 'C', 'C', 'P'):
if (ctx->has_iccp) {
av_log(s, loglevel, "Extra ICCP chunk found\n");
if (explode)
return AVERROR_INVALIDDATA;
avio_skip(pb, size);
} else {
if (!(ctx->vp8x_flags & VP8X_FLAG_ICC)) {
av_log(s, loglevel,
"ICCP chunk present, but ICC Profile bit not set in the VP8X header\n");
if (explode)
return AVERROR_INVALIDDATA;
}
AVPacketSideData *sd = av_packet_side_data_new(&st->codecpar->coded_side_data,
&st->codecpar->nb_coded_side_data,
AV_PKT_DATA_ICC_PROFILE, size, 0);
if (!sd)
return AVERROR(ENOMEM);
ret = avio_read(pb, sd->data, size);
if (ret < 0)
return ret;
ctx->has_iccp = 1;
}
break;
case MKTAG('A', 'N', 'I', 'M'):
if (ctx->has_anim) {
av_log(s, loglevel, "Extra ANIM chunk found\n");
if (explode)
return AVERROR_INVALIDDATA;
avio_skip(pb, size);
} else {
if (size != 6)
return AVERROR_INVALIDDATA;
uint32_t bg_color = avio_rb32(pb);
ctx->loop_count = avio_rl16(pb);
if (ctx->usebgcolor) {
st->codecpar->extradata = av_mallocz(4 + AV_INPUT_BUFFER_PADDING_SIZE);
if (!st->codecpar->extradata)
return AVERROR(ENOMEM);
AV_WB32(st->codecpar->extradata, bg_color);
st->codecpar->extradata_size = 4;
}
av_log(s, AV_LOG_DEBUG,
"ANIM: background BGRA 0x%08x loop count %d\n",
bg_color, ctx->loop_count);
ctx->has_anim = 1;
}
break;
case MKTAG('A', 'N', 'M', 'F'):
if (!ctx->has_anim) {
av_log(s, loglevel,
"ANMF chunk present, but no previous ANIM chunk found\n");
if (explode)
return AVERROR_INVALIDDATA;
ctx->loop_count = 1;
} else if (!ctx->ignore_loop && ctx->loop_count != 1) {
int64_t file_size = avio_size(pb);
if (file_size < 0 || offset < 0 ||
(ret = ffio_ensure_seekback(pb, file_size - offset)) < 0) {
av_log(s, AV_LOG_WARNING,
"Could not ensure seekback, will not loop\n");
ctx->loop_count = 1;
}
}
ctx->first_anmf_offset = offset;
ret = avio_seek(pb, -8, SEEK_CUR);
if (ret < 0)
return ret;
return 0;
default:
av_log(s, AV_LOG_WARNING, "Skipping chunk: %s\n", av_fourcc2str(fourcc));
avio_skip(pb, size);
break;
}
}
return AVERROR_INVALIDDATA;
}
static int webp_anim_read_packet(AVFormatContext *s, AVPacket *pkt)
{
WebPAnimDemuxContext *ctx = s->priv_data;
AVIOContext *pb = s->pb;
int ret;
int explode = (s->error_recognition & AV_EF_EXPLODE);
int loglevel = explode ? AV_LOG_ERROR : AV_LOG_WARNING;
while (1) {
int64_t offset = avio_tell(pb);
uint32_t fourcc = avio_rl32(pb);
uint32_t size = avio_rl32(pb);
if (size == UINT32_MAX)
return AVERROR_INVALIDDATA;
size += size & 1;
if (avio_feof(pb)) {
if (!ctx->ignore_loop &&
(ctx->loop_count == 0 || ++ctx->cur_loop < ctx->loop_count)) {
ctx->cur_frame = 0;
ret = avio_seek(pb, ctx->first_anmf_offset, SEEK_SET);
if (ret < 0)
return ret;
continue;
}
break;
}
av_log(s, AV_LOG_DEBUG, "Chunk %s of size %u at offset %" PRId64 "\n",
av_fourcc2str(fourcc), size, offset);
switch (fourcc) {
case MKTAG('A', 'N', 'M', 'F'):
if (size < 16)
return AVERROR_INVALIDDATA;
ret = av_get_packet(pb, pkt, size);
if (ret < 0)
return ret;
if (!ctx->cur_frame++)
pkt->flags |= AV_PKT_FLAG_KEY;
pkt->pts = AV_NOPTS_VALUE;
pkt->dts = AV_NOPTS_VALUE;
uint32_t duration = AV_RL24(pkt->data + 12);
if (duration <= ctx->min_delay)
duration = ctx->default_delay;
pkt->duration = FFMIN(duration, ctx->max_delay);
return ret;
case MKTAG('E', 'X', 'I', 'F'):
if (ctx->has_exif) {
av_log(s, loglevel, "Extra EXIF chunk found\n");
if (explode)
return AVERROR_INVALIDDATA;
avio_skip(pb, size);
} else {
if (!(ctx->vp8x_flags & VP8X_FLAG_EXIF_METADATA)) {
av_log(s, loglevel,
"EXIF chunk present, but EXIF bit not set in the VP8X header\n");
if (explode)
return AVERROR_INVALIDDATA;
}
AVStream *st = s->streams[0];
AVPacketSideData *sd = av_packet_side_data_new(&st->codecpar->coded_side_data,
&st->codecpar->nb_coded_side_data,
AV_PKT_DATA_EXIF, size, 0);
if (!sd)
return AVERROR(ENOMEM);
ret = avio_read(pb, sd->data, size);
if (ret < 0)
return ret;
ctx->has_exif = 1;
}
break;
case MKTAG('X', 'M', 'P', ' '):
if (ctx->has_xmp) {
av_log(s, loglevel, "Extra XMP chunk found\n");
if (explode)
return AVERROR_INVALIDDATA;
avio_skip(pb, size);
} else {
if (!(ctx->vp8x_flags & VP8X_FLAG_XMP_METADATA)) {
av_log(s, loglevel,
"XMP chunk present, but XMP bit not set in the VP8X header\n");
if (explode)
return AVERROR_INVALIDDATA;
}
uint8_t *xmp = av_malloc(size + 1);
if (!xmp)
return AVERROR(ENOMEM);
ret = ffio_read_size(pb, xmp, size);
if (ret < 0) {
av_free(xmp);
return ret;
}
xmp[size] = '\0';
av_dict_set(&s->metadata, "xmp", xmp, AV_DICT_DONT_STRDUP_VAL);
ctx->has_xmp = 1;
}
break;
default:
av_log(s, AV_LOG_WARNING, "Skipping chunk: %s\n", av_fourcc2str(fourcc));
avio_skip(pb, size);
break;
}
}
return AVERROR_EOF;
}
static const AVOption options[] = {
{ "min_delay", "minimum valid delay between frames (in milliseconds)", offsetof(WebPAnimDemuxContext, min_delay), AV_OPT_TYPE_INT, {.i64 = WEBP_MIN_DELAY}, 0, 1000 * 60, AV_OPT_FLAG_DECODING_PARAM },
{ "max_webp_delay", "maximum valid delay between frames (in milliseconds)", offsetof(WebPAnimDemuxContext, max_delay), AV_OPT_TYPE_INT, {.i64 = 0xffffff}, 0, 0xffffff, AV_OPT_FLAG_DECODING_PARAM },
{ "default_delay", "default delay between frames (in milliseconds)", offsetof(WebPAnimDemuxContext, default_delay), AV_OPT_TYPE_INT, {.i64 = WEBP_DEFAULT_DELAY}, 0, 1000 * 60, AV_OPT_FLAG_DECODING_PARAM },
{ "ignore_loop", "ignore loop setting", offsetof(WebPAnimDemuxContext, ignore_loop), AV_OPT_TYPE_BOOL, {.i64 = 1}, 0, 1, AV_OPT_FLAG_DECODING_PARAM },
{ "usebgcolor", "use background color from ANIM chunk", offsetof(WebPAnimDemuxContext, usebgcolor), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, AV_OPT_FLAG_DECODING_PARAM },
{ NULL },
};
static const AVClass demuxer_class = {
.class_name = "Animated WebP demuxer",
.item_name = av_default_item_name,
.option = options,
.version = LIBAVUTIL_VERSION_INT,
.category = AV_CLASS_CATEGORY_DEMUXER,
};
const FFInputFormat ff_webp_anim_demuxer = {
.p.name = "webp_anim",
.p.long_name = NULL_IF_CONFIG_SMALL("Animated WebP"),
.p.flags = AVFMT_GENERIC_INDEX,
.p.priv_class = &demuxer_class,
.priv_data_size = sizeof(WebPAnimDemuxContext),
.read_probe = webp_anim_probe,
.read_header = webp_anim_read_header,
.read_packet = webp_anim_read_packet,
};