/* * 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; uint8_t *extra_data; int extra_data_size; } 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; AVCodecParameters *par = format_context->streams[0]->codecpar; if (format_context->nb_streams != 1 || format_context->streams[0]->codecpar->codec_type != AVMEDIA_TYPE_VIDEO || format_context->streams[0]->codecpar->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 if (par->extradata_size) { apng->extra_data = av_mallocz(par->extradata_size + AV_INPUT_BUFFER_PADDING_SIZE); if (!apng->extra_data) return AVERROR(ENOMEM); apng->extra_data_size = par->extradata_size; memcpy(apng->extra_data, par->extradata, par->extradata_size); } return 0; } static int 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]; uint8_t *side_data = NULL; int side_data_size = 0; av_assert0(apng->prev_packet); side_data = av_packet_get_side_data(apng->prev_packet, AV_PKT_DATA_NEW_EXTRADATA, &side_data_size); if (side_data_size) { av_freep(&apng->extra_data); apng->extra_data = av_mallocz(side_data_size + AV_INPUT_BUFFER_PADDING_SIZE); if (!apng->extra_data) return AVERROR(ENOMEM); apng->extra_data_size = side_data_size; memcpy(apng->extra_data, side_data, apng->extra_data_size); } if (apng->frame_number == 0 && !packet) { uint8_t *existing_acTL_chunk; uint8_t *existing_fcTL_chunk; av_log(format_context, AV_LOG_INFO, "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'), apng->extra_data, apng->extra_data_size); if (existing_acTL_chunk) { uint8_t *chunk_after_acTL = existing_acTL_chunk + AV_RB32(existing_acTL_chunk) + 12; avio_write(io_context, apng->extra_data, existing_acTL_chunk - apng->extra_data); avio_write(io_context, chunk_after_acTL, apng->extra_data + apng->extra_data_size - chunk_after_acTL); } else { avio_write(io_context, apng->extra_data, apng->extra_data_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, apng->extra_data, apng->extra_data_size); existing_acTL_chunk = apng_find_chunk(MKBETAG('a', 'c', 'T', 'L'), apng->extra_data, apng->extra_data_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.num > 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_packet_unref(apng->prev_packet); if (packet) av_copy_packet(apng->prev_packet, packet); return 0; } static int apng_write_packet(AVFormatContext *format_context, AVPacket *packet) { APNGMuxContext *apng = format_context->priv_data; int ret; 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 { ret = flush_packet(format_context, packet); if (ret < 0) return ret; } 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]; int ret; if (apng->prev_packet) { ret = flush_packet(format_context, NULL); av_freep(&apng->prev_packet); if (ret < 0) return ret; } 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); } av_freep(&apng->extra_data); apng->extra_data = 0; 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 = "apng", .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, };