diff options
Diffstat (limited to 'libavformat/apngenc.c')
| -rw-r--r-- | libavformat/apngenc.c | 271 |
1 files changed, 271 insertions, 0 deletions
diff --git a/libavformat/apngenc.c b/libavformat/apngenc.c new file mode 100644 index 0000000000..9b2c634b95 --- /dev/null +++ b/libavformat/apngenc.c @@ -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_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'), 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.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_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 = "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, +}; |