diff --git a/Changelog b/Changelog index 5b2899d05b..4e7c1ce2c1 100644 --- a/Changelog +++ b/Changelog @@ -18,6 +18,7 @@ version : - lavu/eval: introduce randomi() function in expressions - VVC decoder - fsync filter +- Raw Captions with Time (RCWT) closed caption muxer version 6.1: - libaribcaption decoder diff --git a/doc/muxers.texi b/doc/muxers.texi index 1c88816c3c..4862540f79 100644 --- a/doc/muxers.texi +++ b/doc/muxers.texi @@ -2583,6 +2583,28 @@ ogg files can be safely chained. @end table +@anchor{rcwt} +@section rcwt + +Raw Captions With Time (RCWT) is a format native to ccextractor, a commonly +used open source tool for processing 608/708 closed caption (CC) sources. +It can be used to archive the original, raw CC bitstream and to produce +a source file for later CC processing or conversion. As a result, +it also allows for interopability with ccextractor for processing CC data +extracted via ffmpeg. The format is simple to parse and can be used +to retain all lines and variants of CC. + +This muxer implements the specification as of 2024-01-05, which has +been stable and unchanged for 10 years as of this writing. + +This muxer will have some nuances from the way that ccextractor muxes RCWT. +No compatibility issues when processing the output with ccextractor +have been observed as a result of this so far, but mileage may vary +and outputs will not be a bit-exact match. + +A free specification of RCWT can be found here: +@url{https://github.com/CCExtractor/ccextractor/blob/master/docs/BINARY_FILE_FORMAT.TXT} + @anchor{segment} @section segment, stream_segment, ssegment diff --git a/libavformat/Makefile b/libavformat/Makefile index 581e378d95..dcc99eeac4 100644 --- a/libavformat/Makefile +++ b/libavformat/Makefile @@ -490,6 +490,7 @@ OBJS-$(CONFIG_QOA_DEMUXER) += qoadec.o OBJS-$(CONFIG_R3D_DEMUXER) += r3d.o OBJS-$(CONFIG_RAWVIDEO_DEMUXER) += rawvideodec.o OBJS-$(CONFIG_RAWVIDEO_MUXER) += rawenc.o +OBJS-$(CONFIG_RCWT_MUXER) += rcwtenc.o subtitles.o OBJS-$(CONFIG_REALTEXT_DEMUXER) += realtextdec.o subtitles.o OBJS-$(CONFIG_REDSPARK_DEMUXER) += redspark.o OBJS-$(CONFIG_RKA_DEMUXER) += rka.o apetag.o img2.o diff --git a/libavformat/allformats.c b/libavformat/allformats.c index ce6be5f04d..b04b43cab3 100644 --- a/libavformat/allformats.c +++ b/libavformat/allformats.c @@ -389,6 +389,7 @@ extern const AVInputFormat ff_qoa_demuxer; extern const AVInputFormat ff_r3d_demuxer; extern const AVInputFormat ff_rawvideo_demuxer; extern const FFOutputFormat ff_rawvideo_muxer; +extern const FFOutputFormat ff_rcwt_muxer; extern const AVInputFormat ff_realtext_demuxer; extern const AVInputFormat ff_redspark_demuxer; extern const AVInputFormat ff_rka_demuxer; diff --git a/libavformat/rcwtenc.c b/libavformat/rcwtenc.c new file mode 100644 index 0000000000..839436ce84 --- /dev/null +++ b/libavformat/rcwtenc.c @@ -0,0 +1,202 @@ +/* + * Raw Captions With Time (RCWT) muxer + * Author: Marth64 + * + * 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 + */ + +/* + * Raw Captions With Time (RCWT) is a format native to ccextractor, a commonly + * used open source tool for processing 608/708 closed caption (CC) sources. + * It can be used to archive the original, raw CC bitstream and to produce + * a source file for later CC processing or conversion. As a result, + * it also allows for interopability with ccextractor for processing CC data + * extracted via ffmpeg. The format is simple to parse and can be used + * to retain all lines and variants of CC. + * + * This muxer implements the specification as of 2024-01-05, which has + * been stable and unchanged for 10 years as of this writing. + * + * This muxer will have some nuances from the way that ccextractor muxes RCWT. + * No compatibility issues when processing the output with ccextractor + * have been observed as a result of this so far, but mileage may vary + * and outputs will not be a bit-exact match. + * + * Specifically, the differences are: + * (1) This muxer will identify as "FF" as the writing program identifier, so + * as to be honest about the output's origin. + * + * (2) ffmpeg's MPEG-1/2, H264, HEVC, etc. decoders extract closed captioning + * data differently than ccextractor from embedded SEI/user data. + * For example, DVD captioning bytes will be translated to ATSC A53 format. + * This allows ffmpeg to handle 608/708 in a consistant way downstream. + * This is a lossless conversion and the meaningful data is retained. + * + * (3) This muxer will not alter the extracted data except to remove invalid + * packets in between valid CC blocks. On the other hand, ccextractor + * will by default remove mid-stream padding, and add padding at the end + * of the stream (in order to convey the end time of the source video). + * + * A free specification of RCWT can be found here: + * @url{https://github.com/CCExtractor/ccextractor/blob/master/docs/BINARY_FILE_FORMAT.TXT} + */ + +#include "avformat.h" +#include "internal.h" +#include "mux.h" +#include "libavutil/log.h" +#include "libavutil/intreadwrite.h" + +#define RCWT_CLUSTER_MAX_BLOCKS 65535 +#define RCWT_BLOCK_SIZE 3 + +typedef struct RCWTContext { + int cluster_nb_blocks; + int cluster_pos; + int64_t cluster_pts; + uint8_t cluster_buf[RCWT_CLUSTER_MAX_BLOCKS * RCWT_BLOCK_SIZE]; +} RCWTContext; + +static void rcwt_init_cluster(AVFormatContext *avf) +{ + RCWTContext *rcwt = avf->priv_data; + + rcwt->cluster_nb_blocks = 0; + rcwt->cluster_pos = 0; + rcwt->cluster_pts = AV_NOPTS_VALUE; + memset(rcwt->cluster_buf, 0, sizeof(rcwt->cluster_buf)); +} + +static void rcwt_flush_cluster(AVFormatContext *avf) +{ + RCWTContext *rcwt = avf->priv_data; + + if (rcwt->cluster_nb_blocks > 0) { + avio_wl64(avf->pb, rcwt->cluster_pts); + avio_wl16(avf->pb, rcwt->cluster_nb_blocks); + avio_write(avf->pb, rcwt->cluster_buf, (rcwt->cluster_nb_blocks * RCWT_BLOCK_SIZE)); + } + + rcwt_init_cluster(avf); +} + +static int rcwt_write_header(AVFormatContext *avf) +{ + if (avf->nb_streams != 1 || avf->streams[0]->codecpar->codec_id != AV_CODEC_ID_EIA_608) { + av_log(avf, AV_LOG_ERROR, + "RCWT supports only one CC (608/708) stream, more than one stream was " + "provided or its codec type was not CC (608/708)\n"); + return AVERROR(EINVAL); + } + + avpriv_set_pts_info(avf->streams[0], 64, 1, 1000); + + /* magic number */ + avio_wb16(avf->pb, 0xCCCC); + avio_w8(avf->pb, 0xED); + + /* program version (identify as ffmpeg) */ + avio_wb16(avf->pb, 0xFF00); + avio_w8(avf->pb, 0x60); + + /* format version, only version 0.001 supported for now */ + avio_wb16(avf->pb, 0x0001); + + /* reserved */ + avio_wb16(avf->pb, 0x000); + avio_w8(avf->pb, 0x00); + + rcwt_init_cluster(avf); + + return 0; +} + +static int rcwt_write_packet(AVFormatContext *avf, AVPacket *pkt) +{ + RCWTContext *rcwt = avf->priv_data; + + int in_block = 0; + int nb_block_bytes = 0; + + if (pkt->size == 0) + return 0; + + /* new PTS, new cluster */ + if (pkt->pts != rcwt->cluster_pts) { + rcwt_flush_cluster(avf); + rcwt->cluster_pts = pkt->pts; + } + + if (pkt->pts == AV_NOPTS_VALUE) { + av_log(avf, AV_LOG_WARNING, "Ignoring CC packet with no PTS\n"); + return 0; + } + + for (int i = 0; i < pkt->size; i++) { + uint8_t cc_valid; + uint8_t cc_type; + + if (rcwt->cluster_nb_blocks == RCWT_CLUSTER_MAX_BLOCKS) { + av_log(avf, AV_LOG_WARNING, "Starting new cluster due to size\n"); + rcwt_flush_cluster(avf); + } + + cc_valid = (pkt->data[i] & 0x04) >> 2; + cc_type = pkt->data[i] & 0x03; + + if (!in_block && !(cc_valid || cc_type == 3)) + continue; + + memcpy(&rcwt->cluster_buf[rcwt->cluster_pos], &pkt->data[i], 1); + rcwt->cluster_pos++; + + if (!in_block) { + in_block = 1; + nb_block_bytes = 1; + continue; + } + + nb_block_bytes++; + + if (nb_block_bytes == RCWT_BLOCK_SIZE) { + in_block = 0; + nb_block_bytes = 0; + rcwt->cluster_nb_blocks++; + } + } + + return 0; +} + +static int rcwt_write_trailer(AVFormatContext *avf) +{ + rcwt_flush_cluster(avf); + + return 0; +} + +const FFOutputFormat ff_rcwt_muxer = { + .p.name = "rcwt", + .p.long_name = NULL_IF_CONFIG_SMALL("Raw Captions With Time"), + .p.extensions = "bin", + .p.flags = AVFMT_GLOBALHEADER | AVFMT_VARIABLE_FPS | AVFMT_TS_NONSTRICT, + .p.subtitle_codec = AV_CODEC_ID_EIA_608, + .priv_data_size = sizeof(RCWTContext), + .write_header = rcwt_write_header, + .write_packet = rcwt_write_packet, + .write_trailer = rcwt_write_trailer +}; diff --git a/tests/fate/subtitles.mak b/tests/fate/subtitles.mak index 59595b9cc1..d7edd31e85 100644 --- a/tests/fate/subtitles.mak +++ b/tests/fate/subtitles.mak @@ -118,6 +118,9 @@ fate-sub-scc: CMD = fmtstdout ass -ss 57 -i $(TARGET_SAMPLES)/sub/witch.scc FATE_SUBTITLES-$(call DEMMUX, SCC, SCC) += fate-sub-scc-remux fate-sub-scc-remux: CMD = fmtstdout scc -i $(TARGET_SAMPLES)/sub/witch.scc -ss 4:00 -map 0 -c copy +FATE_SUBTITLES-$(call DEMMUX, SCC, RCWT) += fate-sub-rcwt +fate-sub-rcwt: CMD = md5 -i $(TARGET_SAMPLES)/sub/witch.scc -map 0 -c copy -f rcwt + FATE_SUBTITLES-$(call ALLYES, MPEGTS_DEMUXER DVBSUB_DECODER DVBSUB_ENCODER) += fate-sub-dvb fate-sub-dvb: CMD = framecrc -i $(TARGET_SAMPLES)/sub/dvbsubtest_filter.ts -map s:0 -c dvbsub