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apng: Add a basic APNG muxer

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Additionally, update some documentation with support for APNG

Signed-off-by: Donny Yang <work@kota.moe>
Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Donny Yang 2015-03-28 19:06:24 +11:00 committed by Michael Niedermayer
parent d759844863
commit 80be7daaa8
5 changed files with 276 additions and 1 deletions
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1
Changelog
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@ -12,6 +12,7 @@ version <next>:
- Detelecine filter
- Intel QSV-accelerated H.264 encoding
- MMAL-accelerated H.264 decoding
- basic APNG encoder and muxer
version 2.6:

2
doc/general.texi
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@ -222,6 +222,7 @@ library:
@tab Audio format used on the Nintendo Gamecube.
@item AFC @tab @tab X
@tab Audio format used on the Nintendo Gamecube.
@item APNG @tab X @tab X
@item ASF @tab X @tab X
@item AST @tab X @tab X
@tab Audio format used on the Nintendo Wii.
@ -508,6 +509,7 @@ following image formats are supported:
@item Alias PIX @tab X @tab X
@tab Alias/Wavefront PIX image format
@item animated GIF @tab X @tab X
@item APNG @tab X @tab X
@item BMP @tab X @tab X
@tab Microsoft BMP image
@item BRender PIX @tab @tab X

1
libavformat/Makefile
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@ -80,6 +80,7 @@ OBJS-$(CONFIG_ANM_DEMUXER) += anm.o
OBJS-$(CONFIG_APC_DEMUXER) += apc.o
OBJS-$(CONFIG_APE_DEMUXER) += ape.o apetag.o img2.o
OBJS-$(CONFIG_APNG_DEMUXER) += apngdec.o
OBJS-$(CONFIG_APNG_MUXER) += apngenc.o
OBJS-$(CONFIG_AQTITLE_DEMUXER) += aqtitledec.o subtitles.o
OBJS-$(CONFIG_ASF_DEMUXER) += asfdec.o asf.o asfcrypt.o \
avlanguage.o

2
libavformat/allformats.c
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@ -74,7 +74,7 @@ void av_register_all(void)
REGISTER_DEMUXER (ANM, anm);
REGISTER_DEMUXER (APC, apc);
REGISTER_DEMUXER (APE, ape);
REGISTER_DEMUXER (APNG, apng);
REGISTER_MUXDEMUX(APNG, apng);
REGISTER_DEMUXER (AQTITLE, aqtitle);
REGISTER_MUXDEMUX(ASF, asf);
REGISTER_MUXDEMUX(ASS, ass);

271
libavformat/apngenc.c Normal file
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@ -0,0 +1,271 @@
/*
* APNG muxer
* Copyright (c) 2015 Donny Yang
*
* first version by Donny Yang <work@kota.moe>
*
* 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
*/
#include "avformat.h"
#include "internal.h"
#include "libavutil/avassert.h"
#include "libavutil/crc.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/log.h"
#include "libavutil/opt.h"
#include "libavcodec/png.h"
#include "libavcodec/apng.h"
typedef struct APNGMuxContext {
AVClass *class;
uint32_t plays;
AVRational last_delay;
uint64_t acTL_offset;
uint32_t frame_number;
AVPacket *prev_packet;
AVRational prev_delay;
int framerate_warned;
} APNGMuxContext;
static uint8_t *apng_find_chunk(uint32_t tag, uint8_t *buf, size_t length)
{
size_t b;
for (b = 0; b < length; b += AV_RB32(buf + b) + 12)
if (AV_RB32(&buf[b + 4]) == tag)
return &buf[b];
return NULL;
}
static void apng_write_chunk(AVIOContext *io_context, uint32_t tag,
uint8_t *buf, size_t length)
{
const AVCRC *crc_table = av_crc_get_table(AV_CRC_32_IEEE_LE);
uint32_t crc = ~0U;
uint8_t tagbuf[4];
av_assert0(crc_table);
avio_wb32(io_context, length);
AV_WB32(tagbuf, tag);
crc = av_crc(crc_table, crc, tagbuf, 4);
avio_wb32(io_context, tag);
if (length > 0) {
crc = av_crc(crc_table, crc, buf, length);
avio_write(io_context, buf, length);
}
avio_wb32(io_context, ~crc);
}
static int apng_write_header(AVFormatContext *format_context)
{
APNGMuxContext *apng = format_context->priv_data;
if (format_context->nb_streams != 1 ||
format_context->streams[0]->codec->codec_type != AVMEDIA_TYPE_VIDEO ||
format_context->streams[0]->codec->codec_id != AV_CODEC_ID_APNG) {
av_log(format_context, AV_LOG_ERROR,
"APNG muxer supports only a single video APNG stream.\n");
return AVERROR(EINVAL);
}
if (apng->last_delay.num > USHRT_MAX || apng->last_delay.den > USHRT_MAX) {
av_reduce(&apng->last_delay.num, &apng->last_delay.den,
apng->last_delay.num, apng->last_delay.den, USHRT_MAX);
av_log(format_context, AV_LOG_WARNING,
"Last frame delay is too precise. Reducing to %d/%d (%f).\n",
apng->last_delay.num, apng->last_delay.den, (double)apng->last_delay.num / apng->last_delay.den);
}
avio_wb64(format_context->pb, PNGSIG);
// Remaining headers are written when they are copied from the encoder
return 0;
}
static void flush_packet(AVFormatContext *format_context, AVPacket *packet)
{
APNGMuxContext *apng = format_context->priv_data;
AVIOContext *io_context = format_context->pb;
AVStream *codec_stream = format_context->streams[0];
AVCodecContext *codec_context = codec_stream->codec;
av_assert0(apng->prev_packet);
if (apng->frame_number == 0 && !packet) {
uint8_t *existing_acTL_chunk;
uint8_t *existing_fcTL_chunk;
av_log(format_context, AV_LOG_WARNING, "Only a single frame so saving as a normal PNG.\n");
// Write normal PNG headers without acTL chunk
existing_acTL_chunk = apng_find_chunk(MKBETAG('a', 'c', 'T', 'L'), codec_context->extradata, codec_context->extradata_size);
if (existing_acTL_chunk) {
uint8_t *chunk_after_acTL = existing_acTL_chunk + AV_RB32(existing_acTL_chunk) + 12;
avio_write(io_context, codec_context->extradata, existing_acTL_chunk - codec_context->extradata);
avio_write(io_context, chunk_after_acTL, codec_context->extradata + codec_context->extradata_size - chunk_after_acTL);
} else {
avio_write(io_context, codec_context->extradata, codec_context->extradata_size);
}
// Write frame data without fcTL chunk
existing_fcTL_chunk = apng_find_chunk(MKBETAG('f', 'c', 'T', 'L'), apng->prev_packet->data, apng->prev_packet->size);
if (existing_fcTL_chunk) {
uint8_t *chunk_after_fcTL = existing_fcTL_chunk + AV_RB32(existing_fcTL_chunk) + 12;
avio_write(io_context, apng->prev_packet->data, existing_fcTL_chunk - apng->prev_packet->data);
avio_write(io_context, chunk_after_fcTL, apng->prev_packet->data + apng->prev_packet->size - chunk_after_fcTL);
} else {
avio_write(io_context, apng->prev_packet->data, apng->prev_packet->size);
}
} else {
uint8_t *existing_fcTL_chunk;
if (apng->frame_number == 0) {
uint8_t *existing_acTL_chunk;
// Write normal PNG headers
avio_write(io_context, codec_context->extradata, codec_context->extradata_size);
existing_acTL_chunk = apng_find_chunk(MKBETAG('a', 'c', 'T', 'L'), codec_context->extradata, codec_context->extradata_size);
if (!existing_acTL_chunk) {
uint8_t buf[8];
// Write animation control header
apng->acTL_offset = avio_tell(io_context);
AV_WB32(buf, UINT_MAX); // number of frames (filled in later)
AV_WB32(buf + 4, apng->plays);
apng_write_chunk(io_context, MKBETAG('a', 'c', 'T', 'L'), buf, 8);
}
}
existing_fcTL_chunk = apng_find_chunk(MKBETAG('f', 'c', 'T', 'L'), apng->prev_packet->data, apng->prev_packet->size);
if (existing_fcTL_chunk) {
AVRational delay;
existing_fcTL_chunk += 8;
delay.num = AV_RB16(existing_fcTL_chunk + 20);
delay.den = AV_RB16(existing_fcTL_chunk + 22);
if (delay.num == 0 && delay.den == 0) {
if (packet) {
int64_t delay_num_raw = (packet->dts - apng->prev_packet->dts) * codec_stream->time_base.num;
int64_t delay_den_raw = codec_stream->time_base.den;
if (!av_reduce(&delay.num, &delay.den, delay_num_raw, delay_den_raw, USHRT_MAX) &&
!apng->framerate_warned) {
av_log(format_context, AV_LOG_WARNING,
"Frame rate is too high or specified too precisely. Unable to copy losslessly.\n");
apng->framerate_warned = 1;
}
} else if (apng->last_delay.den > 0) {
delay = apng->last_delay;
} else {
delay = apng->prev_delay;
}
// Update frame control header with new delay
AV_WB16(existing_fcTL_chunk + 20, delay.num);
AV_WB16(existing_fcTL_chunk + 22, delay.den);
AV_WB32(existing_fcTL_chunk + 26, ~av_crc(av_crc_get_table(AV_CRC_32_IEEE_LE), ~0U, existing_fcTL_chunk - 4, 26 + 4));
}
apng->prev_delay = delay;
}
// Write frame data
avio_write(io_context, apng->prev_packet->data, apng->prev_packet->size);
}
++apng->frame_number;
av_free_packet(apng->prev_packet);
if (packet)
av_copy_packet(apng->prev_packet, packet);
}
static int apng_write_packet(AVFormatContext *format_context, AVPacket *packet)
{
APNGMuxContext *apng = format_context->priv_data;
if (!apng->prev_packet) {
apng->prev_packet = av_malloc(sizeof(*apng->prev_packet));
if (!apng->prev_packet)
return AVERROR(ENOMEM);
av_copy_packet(apng->prev_packet, packet);
} else {
flush_packet(format_context, packet);
}
return 0;
}
static int apng_write_trailer(AVFormatContext *format_context)
{
APNGMuxContext *apng = format_context->priv_data;
AVIOContext *io_context = format_context->pb;
uint8_t buf[8];
if (apng->prev_packet) {
flush_packet(format_context, NULL);
av_freep(&apng->prev_packet);
}
apng_write_chunk(io_context, MKBETAG('I', 'E', 'N', 'D'), NULL, 0);
if (apng->acTL_offset && io_context->seekable) {
avio_seek(io_context, apng->acTL_offset, SEEK_SET);
AV_WB32(buf, apng->frame_number);
AV_WB32(buf + 4, apng->plays);
apng_write_chunk(io_context, MKBETAG('a', 'c', 'T', 'L'), buf, 8);
}
return 0;
}
#define OFFSET(x) offsetof(APNGMuxContext, x)
#define ENC AV_OPT_FLAG_ENCODING_PARAM
static const AVOption options[] = {
{ "plays", "Number of times to play the output: 0 - infinite loop, 1 - no loop", OFFSET(plays),
AV_OPT_TYPE_INT, { .i64 = 1 }, 0, UINT_MAX, ENC },
{ "final_delay", "Force delay after the last frame", OFFSET(last_delay),
AV_OPT_TYPE_RATIONAL, { .dbl = 0 }, 0, USHRT_MAX, ENC },
{ NULL },
};
static const AVClass apng_muxer_class = {
.class_name = "APNG muxer",
.item_name = av_default_item_name,
.version = LIBAVUTIL_VERSION_INT,
.option = options,
};
AVOutputFormat ff_apng_muxer = {
.name = "apng",
.long_name = NULL_IF_CONFIG_SMALL("Animated Portable Network Graphics"),
.mime_type = "image/png",
.extensions = "png",
.priv_data_size = sizeof(APNGMuxContext),
.audio_codec = AV_CODEC_ID_NONE,
.video_codec = AV_CODEC_ID_APNG,
.write_header = apng_write_header,
.write_packet = apng_write_packet,
.write_trailer = apng_write_trailer,
.priv_class = &apng_muxer_class,
.flags = AVFMT_VARIABLE_FPS,
};