Marth64: > RCWT (Raw Captions With Time) is a format native to ccextractor, > a commonly used OSS tool for processing 608/708 Closed Captions (CC). > RCWT can be used to archive the original extracted CC bitstream. > The muxer was added in January 2024. In this commit, add the demuxer. > > One can now demux RCWT files for rendering in ccaption_dec or interop > with ccextractor (which produces RCWT). Using the muxer/demuxer combo, > the CC bits can be kept for processing or rendering with either tool. > This can be an effective way to backup an original CC stream, including > format extensions like EIA-708 and overall original presentation. > > Signed-off-by: Marth64 <mart...@proxyid.net> > --- > Changelog | 2 +- > doc/demuxers.texi | 30 ++++++++++ > libavformat/Makefile | 1 + > libavformat/allformats.c | 1 + > libavformat/rcwtdec.c | 123 +++++++++++++++++++++++++++++++++++++++ > 5 files changed, 156 insertions(+), 1 deletion(-) > create mode 100644 libavformat/rcwtdec.c > > diff --git a/Changelog b/Changelog > index e3ca52430c..0ae05c6cce 100644 > --- a/Changelog > +++ b/Changelog > @@ -19,7 +19,7 @@ version <next>: > - lavu/eval: introduce randomi() function in expressions > - VVC decoder > - fsync filter > -- Raw Captions with Time (RCWT) closed caption muxer > +- RCWT (Raw Captions with Time) Closed Captions muxer and demuxer > - ffmpeg CLI -bsf option may now be used for input as well as output > - ffmpeg CLI options may now be used as -/opt <path>, which is equivalent > to -opt <contents of file <path>> > diff --git a/doc/demuxers.texi b/doc/demuxers.texi > index b70f3a38d7..b4c4daacd9 100644 > --- a/doc/demuxers.texi > +++ b/doc/demuxers.texi > @@ -1038,6 +1038,36 @@ the command: > ffplay -f rawvideo -pixel_format rgb24 -video_size 320x240 -framerate 10 > input.raw > @end example > > +@anchor{rcwtdec} > +@section rcwt > + > +RCWT (Raw Captions With Time) is a format native to ccextractor, a commonly > +used open source tool for processing 608/708 Closed Captions (CC) sources. > +For more information on the format, see @ref{rcwtenc,,,ffmpeg-formats}. > + > +This demuxer implements the specification as of March 2024, which has > +been stable and unchanged since April 2014. > + > +@subsection Examples > + > +@itemize > +@item > +Render Closed Captions to ASS, using the CC decoder (cc_dec): > +@example > +ffmpeg -i CC.rcwt.bin CC.ass > +@end example > +Note that if your output appears to be empty, you may have to manually > +set the decoder's @option{data_field} option to pick the desired CC > substream. > + > +@item > +Convert an RCWT backup to SCC format, using the SCC muxer (scc): > +@example > +ffmpeg -i CC.rcwt.bin -c:s copy CC.scc > +@end example > +Note that the SCC format does not support all of the possible CC formats > +that can be stored in RCWT. > +@end itemize > + > @section sbg > > SBaGen script demuxer. > diff --git a/libavformat/Makefile b/libavformat/Makefile > index 94a949f555..a6de720d8c 100644 > --- a/libavformat/Makefile > +++ b/libavformat/Makefile > @@ -493,6 +493,7 @@ 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-$(CONFIG_RCWT_DEMUXER) += rcwtdec.o subtitles.o > OBJS-$(CONFIG_RCWT_MUXER) += rcwtenc.o subtitles.o > OBJS-$(CONFIG_REALTEXT_DEMUXER) += realtextdec.o subtitles.o > OBJS-$(CONFIG_REDSPARK_DEMUXER) += redspark.o > diff --git a/libavformat/allformats.c b/libavformat/allformats.c > index e15d0fa6d7..3140018f8d 100644 > --- a/libavformat/allformats.c > +++ b/libavformat/allformats.c > @@ -391,6 +391,7 @@ extern const FFInputFormat ff_qoa_demuxer; > extern const FFInputFormat ff_r3d_demuxer; > extern const FFInputFormat ff_rawvideo_demuxer; > extern const FFOutputFormat ff_rawvideo_muxer; > +extern const FFInputFormat ff_rcwt_demuxer; > extern const FFOutputFormat ff_rcwt_muxer; > extern const FFInputFormat ff_realtext_demuxer; > extern const FFInputFormat ff_redspark_demuxer; > diff --git a/libavformat/rcwtdec.c b/libavformat/rcwtdec.c > new file mode 100644 > index 0000000000..e5cd05ea3e > --- /dev/null > +++ b/libavformat/rcwtdec.c > @@ -0,0 +1,123 @@ > +/* > + * RCWT (Raw Captions With Time) demuxer > + * > + * 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 > + */ > + > +/* > + * RCWT (Raw Captions With Time) is a format native to ccextractor, a > commonly > + * used open source tool for processing 608/708 Closed Captions (CC) sources. > + * > + * This demuxer implements the specification as of March 2024, which has > + * been stable and unchanged since April 2014. > + * > + * 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 "demux.h" > +#include "internal.h" > +#include "subtitles.h" > +#include "libavutil/intreadwrite.h" > + > +#define RCWT_HEADER_SIZE 11 > + > +typedef struct RCWTContext { > + FFDemuxSubtitlesQueue q; > +} RCWTContext; > + > +static int rcwt_read_header(AVFormatContext *avf) > +{ > + RCWTContext *rcwt = avf->priv_data; > + > + AVStream *st; > + uint8_t header[RCWT_HEADER_SIZE]; > + int nb_bytes; > + > + /* read header */ > + nb_bytes = ffio_read_size(avf->pb, header, RCWT_HEADER_SIZE); > + if (nb_bytes != RCWT_HEADER_SIZE) > + return AVERROR_INVALIDDATA;
ret = ffio_read_size() if (ret < 0) return ret; (I dislike that we return AVERROR_INVALIDDATA when a file is truncated; IMO a dedicated error code for that would be better and if one were ever introduced, my code above would automatically use if ffio_read_size() alone is updated.) > + > + if (AV_RB16(header + 6) != 0x0001) { > + av_log(avf, AV_LOG_ERROR, "RCWT format version is not compatible " > + "(only version 0.001 is known)\n"); > + return AVERROR_INVALIDDATA; > + } > + > + av_log(avf, AV_LOG_DEBUG, "RCWT writer application: %02X version: > %02x\n", > + header[3], header[5]); > + > + /* setup stream */ > + st = avformat_new_stream(avf, NULL); > + if (!st) > + return AVERROR(ENOMEM); > + > + st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE; > + st->codecpar->codec_id = AV_CODEC_ID_EIA_608; > + > + avpriv_set_pts_info(st, 64, 1, 1000); > + > + /* demux */ > + while (!avio_feof(avf->pb)) { > + AVPacket *sub; > + int ret; > + int64_t cluster_pos = avio_tell(avf->pb); > + int64_t cluster_pts = avio_rl64(avf->pb); > + int cluster_nb_blocks = avio_rl16(avf->pb); > + > + if (cluster_nb_blocks == 0) > + continue; > + > + sub = ff_subtitles_queue_insert(&rcwt->q, NULL, 0, 0); > + if (!sub) > + return AVERROR(ENOMEM); > + > + if ((ret = av_get_packet(avf->pb, sub, cluster_nb_blocks * 3)) < 0) Please avoid the "if ((ret = func()) < 0)" style (see fbf1e5135298b for why; I am not claiming that your code is affected by this). > + return ret; > + > + sub->pos = cluster_pos; > + sub->pts = cluster_pts; > + } > + > + ff_subtitles_queue_finalize(avf, &rcwt->q); > + > + return 0; > +} > + > +static int rcwt_probe(const AVProbeData *p) > +{ > + return p->buf_size > RCWT_HEADER_SIZE && > + AV_RB16(p->buf) == 0xCCCC && > + AV_RB8(p->buf + 2) == 0xED && > + AV_RB16(p->buf + 6) == 0x0001 ? 50 : 0; > +} > + > +const FFInputFormat ff_rcwt_demuxer = { > + .p.name = "rcwt", > + .p.long_name = NULL_IF_CONFIG_SMALL("RCWT (Raw Captions With Time)"), > + .p.extensions = "bin", > + .p.flags = AVFMT_TS_DISCONT, > + .priv_data_size = sizeof(RCWTContext), > + .flags_internal = FF_FMT_INIT_CLEANUP, > + .read_probe = rcwt_probe, > + .read_header = rcwt_read_header, > + .read_packet = ff_subtitles_read_packet, > + .read_seek2 = ff_subtitles_read_seek, > + .read_close = ff_subtitles_read_close > +}; _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".