On 09/03/2016 11:26 PM, Andrey Turkin wrote: > AVFrame already has some support for embedded 608/708 subtitles in a form > of side data (AV_FRAME_DATA_A53_CC tag), and some decoders/encoders already > can handle that. > Main issue with this approach is that video frames can be modified, removed > or duplicated (mainly by video filters but also by ffmpeg's video sync > code). > > 2016-09-04 6:14 GMT+03:00 Jonathan Campbell <jonat...@impactstudiopro.com>: > >> While I'm finishing up the CNG patch, I'd like to start developing another >> feature that I think FFMPEG should be able to at least expose through the >> API. >> >> I'm aware that FFMPEG supports subtitle tracks, but as far as I know, >> doesn't support caption data embedded in the video stream itself. >> >> Some scenarios especially in broadcast TV transmit MPEG-2 or H.264 video >> with caption data embedded in the encoded frame. I would like to write a >> patch that can read the caption data embedded in MPEG-2 user packets and >> expose it in the AVFrame. >> >> There are two common forms I work with in software: One carries EIA 608 >> closed caption packets per keyframe (typically seen on DVDs here in >> America), the other carries CEA 708 closed caption data (Caption >> Description Packets) every frame (or every I/P frame) with a side channel >> for 608 (typically seen in terrestrial HDTV broadcast here in America). How >> could I modify the MPEG-2 decoder and/or bitstream parser to read and >> expose this data through the API for software that needs it? I'm also >> interested in modding the MPEG-2 encoder to take this data through the API >> and encode it into the frame. If done right, the extension could allow >> FFMPEG to transcode DVD or HDTV broadcasts while keeping the caption data >> intact. >> >> Similar standards exist to carry caption data packets in H.264 (as SEI >> packets) and DV video (as DIF packets). >> >> Jonathan Campbell >> _______________________________________________ >> ffmpeg-devel mailing list >> ffmpeg-devel@ffmpeg.org >> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel >> > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel > Cool, that's why I asked. I see it now in mpeg12dec.c
It looks like mpeg12enc.c though is lacking the code to read the A53_CC side data and put the caption data into the encoded frame. Mind if I write a patch to do that? Jonathan Campbell _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
