312 lines
11 KiB
C
312 lines
11 KiB
C
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/*
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* APNG muxer
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* Copyright (c) 2015 Donny Yang
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*
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* first version by Donny Yang <work@kota.moe>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "avformat.h"
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#include "internal.h"
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#include "libavutil/avassert.h"
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#include "libavutil/crc.h"
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#include "libavutil/intreadwrite.h"
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#include "libavutil/log.h"
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#include "libavutil/opt.h"
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#include "libavcodec/png.h"
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#include "libavcodec/apng.h"
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typedef struct APNGMuxContext {
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AVClass *class;
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uint32_t plays;
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AVRational last_delay;
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uint64_t acTL_offset;
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uint32_t frame_number;
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AVPacket *prev_packet;
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AVRational prev_delay;
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int framerate_warned;
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uint8_t *extra_data;
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int extra_data_size;
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} APNGMuxContext;
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static uint8_t *apng_find_chunk(uint32_t tag, uint8_t *buf, size_t length)
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{
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size_t b;
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for (b = 0; b < length; b += AV_RB32(buf + b) + 12)
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if (AV_RB32(&buf[b + 4]) == tag)
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return &buf[b];
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return NULL;
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}
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static void apng_write_chunk(AVIOContext *io_context, uint32_t tag,
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uint8_t *buf, size_t length)
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{
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const AVCRC *crc_table = av_crc_get_table(AV_CRC_32_IEEE_LE);
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uint32_t crc = ~0U;
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uint8_t tagbuf[4];
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av_assert0(crc_table);
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avio_wb32(io_context, length);
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AV_WB32(tagbuf, tag);
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crc = av_crc(crc_table, crc, tagbuf, 4);
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avio_wb32(io_context, tag);
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if (length > 0) {
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crc = av_crc(crc_table, crc, buf, length);
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avio_write(io_context, buf, length);
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}
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avio_wb32(io_context, ~crc);
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}
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static int apng_write_header(AVFormatContext *format_context)
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{
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APNGMuxContext *apng = format_context->priv_data;
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AVCodecParameters *par = format_context->streams[0]->codecpar;
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if (format_context->nb_streams != 1 ||
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format_context->streams[0]->codecpar->codec_type != AVMEDIA_TYPE_VIDEO ||
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format_context->streams[0]->codecpar->codec_id != AV_CODEC_ID_APNG) {
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av_log(format_context, AV_LOG_ERROR,
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"APNG muxer supports only a single video APNG stream.\n");
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return AVERROR(EINVAL);
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}
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if (apng->last_delay.num > USHRT_MAX || apng->last_delay.den > USHRT_MAX) {
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av_reduce(&apng->last_delay.num, &apng->last_delay.den,
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apng->last_delay.num, apng->last_delay.den, USHRT_MAX);
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av_log(format_context, AV_LOG_WARNING,
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"Last frame delay is too precise. Reducing to %d/%d (%f).\n",
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apng->last_delay.num, apng->last_delay.den, (double)apng->last_delay.num / apng->last_delay.den);
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}
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avio_wb64(format_context->pb, PNGSIG);
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// Remaining headers are written when they are copied from the encoder
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if (par->extradata_size) {
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apng->extra_data = av_mallocz(par->extradata_size + AV_INPUT_BUFFER_PADDING_SIZE);
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if (!apng->extra_data)
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return AVERROR(ENOMEM);
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apng->extra_data_size = par->extradata_size;
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memcpy(apng->extra_data, par->extradata, par->extradata_size);
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}
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return 0;
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}
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static int flush_packet(AVFormatContext *format_context, AVPacket *packet)
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{
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APNGMuxContext *apng = format_context->priv_data;
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AVIOContext *io_context = format_context->pb;
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AVStream *codec_stream = format_context->streams[0];
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uint8_t *side_data = NULL;
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int side_data_size = 0;
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av_assert0(apng->prev_packet);
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side_data = av_packet_get_side_data(apng->prev_packet, AV_PKT_DATA_NEW_EXTRADATA, &side_data_size);
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if (side_data_size) {
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av_freep(&apng->extra_data);
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apng->extra_data = av_mallocz(side_data_size + AV_INPUT_BUFFER_PADDING_SIZE);
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if (!apng->extra_data)
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return AVERROR(ENOMEM);
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apng->extra_data_size = side_data_size;
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memcpy(apng->extra_data, side_data, apng->extra_data_size);
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}
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if (apng->frame_number == 0 && !packet) {
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uint8_t *existing_acTL_chunk;
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uint8_t *existing_fcTL_chunk;
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av_log(format_context, AV_LOG_INFO, "Only a single frame so saving as a normal PNG.\n");
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// Write normal PNG headers without acTL chunk
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existing_acTL_chunk = apng_find_chunk(MKBETAG('a', 'c', 'T', 'L'), apng->extra_data, apng->extra_data_size);
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if (existing_acTL_chunk) {
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uint8_t *chunk_after_acTL = existing_acTL_chunk + AV_RB32(existing_acTL_chunk) + 12;
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avio_write(io_context, apng->extra_data, existing_acTL_chunk - apng->extra_data);
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avio_write(io_context, chunk_after_acTL, apng->extra_data + apng->extra_data_size - chunk_after_acTL);
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} else {
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avio_write(io_context, apng->extra_data, apng->extra_data_size);
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}
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// Write frame data without fcTL chunk
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existing_fcTL_chunk = apng_find_chunk(MKBETAG('f', 'c', 'T', 'L'), apng->prev_packet->data, apng->prev_packet->size);
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if (existing_fcTL_chunk) {
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uint8_t *chunk_after_fcTL = existing_fcTL_chunk + AV_RB32(existing_fcTL_chunk) + 12;
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avio_write(io_context, apng->prev_packet->data, existing_fcTL_chunk - apng->prev_packet->data);
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avio_write(io_context, chunk_after_fcTL, apng->prev_packet->data + apng->prev_packet->size - chunk_after_fcTL);
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} else {
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avio_write(io_context, apng->prev_packet->data, apng->prev_packet->size);
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}
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} else {
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uint8_t *existing_fcTL_chunk;
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if (apng->frame_number == 0) {
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uint8_t *existing_acTL_chunk;
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// Write normal PNG headers
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avio_write(io_context, apng->extra_data, apng->extra_data_size);
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existing_acTL_chunk = apng_find_chunk(MKBETAG('a', 'c', 'T', 'L'), apng->extra_data, apng->extra_data_size);
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if (!existing_acTL_chunk) {
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uint8_t buf[8];
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// Write animation control header
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apng->acTL_offset = avio_tell(io_context);
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AV_WB32(buf, UINT_MAX); // number of frames (filled in later)
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AV_WB32(buf + 4, apng->plays);
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apng_write_chunk(io_context, MKBETAG('a', 'c', 'T', 'L'), buf, 8);
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}
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}
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existing_fcTL_chunk = apng_find_chunk(MKBETAG('f', 'c', 'T', 'L'), apng->prev_packet->data, apng->prev_packet->size);
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if (existing_fcTL_chunk) {
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AVRational delay;
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existing_fcTL_chunk += 8;
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delay.num = AV_RB16(existing_fcTL_chunk + 20);
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delay.den = AV_RB16(existing_fcTL_chunk + 22);
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if (delay.num == 0 && delay.den == 0) {
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if (packet) {
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int64_t delay_num_raw = (packet->dts - apng->prev_packet->dts) * codec_stream->time_base.num;
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int64_t delay_den_raw = codec_stream->time_base.den;
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if (!av_reduce(&delay.num, &delay.den, delay_num_raw, delay_den_raw, USHRT_MAX) &&
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!apng->framerate_warned) {
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av_log(format_context, AV_LOG_WARNING,
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"Frame rate is too high or specified too precisely. Unable to copy losslessly.\n");
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apng->framerate_warned = 1;
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}
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} else if (apng->last_delay.num > 0) {
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delay = apng->last_delay;
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} else {
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delay = apng->prev_delay;
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}
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// Update frame control header with new delay
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AV_WB16(existing_fcTL_chunk + 20, delay.num);
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AV_WB16(existing_fcTL_chunk + 22, delay.den);
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AV_WB32(existing_fcTL_chunk + 26, ~av_crc(av_crc_get_table(AV_CRC_32_IEEE_LE), ~0U, existing_fcTL_chunk - 4, 26 + 4));
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}
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apng->prev_delay = delay;
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}
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// Write frame data
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avio_write(io_context, apng->prev_packet->data, apng->prev_packet->size);
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}
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++apng->frame_number;
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av_packet_unref(apng->prev_packet);
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if (packet)
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av_packet_ref(apng->prev_packet, packet);
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return 0;
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}
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static int apng_write_packet(AVFormatContext *format_context, AVPacket *packet)
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{
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APNGMuxContext *apng = format_context->priv_data;
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int ret;
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if (!apng->prev_packet) {
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apng->prev_packet = av_packet_alloc();
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if (!apng->prev_packet)
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return AVERROR(ENOMEM);
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av_packet_ref(apng->prev_packet, packet);
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} else {
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ret = flush_packet(format_context, packet);
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if (ret < 0)
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return ret;
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}
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return 0;
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}
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static int apng_write_trailer(AVFormatContext *format_context)
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{
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APNGMuxContext *apng = format_context->priv_data;
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AVIOContext *io_context = format_context->pb;
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uint8_t buf[8];
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int ret;
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if (apng->prev_packet) {
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ret = flush_packet(format_context, NULL);
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if (ret < 0)
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return ret;
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}
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apng_write_chunk(io_context, MKBETAG('I', 'E', 'N', 'D'), NULL, 0);
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if (apng->acTL_offset && (io_context->seekable & AVIO_SEEKABLE_NORMAL)) {
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avio_seek(io_context, apng->acTL_offset, SEEK_SET);
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AV_WB32(buf, apng->frame_number);
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AV_WB32(buf + 4, apng->plays);
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apng_write_chunk(io_context, MKBETAG('a', 'c', 'T', 'L'), buf, 8);
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}
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return 0;
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}
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static void apng_deinit(AVFormatContext *s)
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{
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APNGMuxContext *apng = s->priv_data;
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av_packet_free(&apng->prev_packet);
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av_freep(&apng->extra_data);
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apng->extra_data_size = 0;
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}
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#define OFFSET(x) offsetof(APNGMuxContext, x)
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#define ENC AV_OPT_FLAG_ENCODING_PARAM
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static const AVOption options[] = {
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{ "plays", "Number of times to play the output: 0 - infinite loop, 1 - no loop", OFFSET(plays),
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AV_OPT_TYPE_INT, { .i64 = 1 }, 0, UINT_MAX, ENC },
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{ "final_delay", "Force delay after the last frame", OFFSET(last_delay),
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AV_OPT_TYPE_RATIONAL, { .dbl = 0 }, 0, USHRT_MAX, ENC },
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{ NULL },
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};
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static const AVClass apng_muxer_class = {
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.class_name = "APNG muxer",
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.item_name = av_default_item_name,
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.version = LIBAVUTIL_VERSION_INT,
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.option = options,
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};
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AVOutputFormat ff_apng_muxer = {
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.name = "apng",
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.long_name = NULL_IF_CONFIG_SMALL("Animated Portable Network Graphics"),
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.mime_type = "image/png",
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.extensions = "apng",
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.priv_data_size = sizeof(APNGMuxContext),
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.audio_codec = AV_CODEC_ID_NONE,
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.video_codec = AV_CODEC_ID_APNG,
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.write_header = apng_write_header,
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.write_packet = apng_write_packet,
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.write_trailer = apng_write_trailer,
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.deinit = apng_deinit,
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.priv_class = &apng_muxer_class,
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.flags = AVFMT_VARIABLE_FPS,
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};
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