[FFmpeg-devel] [PATCH 1/2] lavc: add CEA-708 codec id.

[Nicolas George]

Le septidi 27 ventôse, an CCXXII, Reimar Döffinger a écrit :
> It was kind of my idea that we would just have all under a single ID for
> the moment since filtering out the part you want isn't hard, but that was
> in large part due to laziness...
> I believe most if not all wtv samples we have include combined 608 and 708
> data, but I can't test right now (and don't even know they are on the
> sample server).

I have made a small survey of the samles that were pointed in this thread:

http://samples.ffmpeg.org/MPEG2/subcc/HK_DVB_sample.ts
http://samples.ffmpeg.org/MPEG2/subcc/HK_DVB_w_subtitle.ts
http://samples.ffmpeg.org/MPEG2/subcc/HigashiNoEden8CCs.ts
http://samples.ffmpeg.org/MPEG2/subcc/arib-captions.ts
http://samples.ffmpeg.org/MPEG2/subcc/DVR-ClosedCaption/

seem to contain nothing exploitable: either dvb_sub, or nothing visible
(possibly subcc inside H.264 like inside mpeg2video: is it possible? the
decoder does not export it).

http://samples.ffmpeg.org/MPEG2/subcc/test1.mpg
http://samples.ffmpeg.org/MPEG2/subcc/ClosedCaptions/Starship_Troopers.vob
http://samples.ffmpeg.org/MPEG2/subcc/ClosedCaptions/subccItalic.mpg
http://samples.ffmpeg.org/sub/atsc-cea-708-dtvcc-and-cea-608.ts

contain subcc-inside-mpeg2video, and the packets look very much like the
sample I was working with:

00000000: fcd3 68ff 0322 fe53 68fe 0000 fa00 00fa  ..h..".Sh.......
00000010: 0000 fa00 00fa 0000 fa00 00fa 0000       ..............
00000000: fd80 80fa 0000 fa00 00fa 0000 fa00 00fa  ................
00000010: 0000 fa00 00fa 0000 fa00 00fa 0000       ..............
00000000: fce9 6eff 4322 fe69 6efe 0000 fa00 00fa  ..n.C".in.......
00000010: 0000 fa00 00fa 0000 fa00 00fa 0000       ..............
00000000: fd80 80fa 0000 fa00 00fa 0000 fa00 00fa  ................
00000010: 0000 fa00 00fa 0000 fa00 00fa 0000       ..............
00000000: fc79 20ff 8322 fe79 20fe 0000 fa00 00fa  .y ..".y .......
00000010: 0000 fa00 00fa 0000 fa00 00fa 0000       ..............

I can see the subtitles in MPlayer for test1.mpg, subccItalic.mpg and
Starship_Troopers.vob, that gives me a starting point to work.

http://samples.ffmpeg.org/ffmpeg-bugs/trac/ticket1482/NCIS.wtv

contains a stream flagged "eia_608" with packets that look like that:

00000000: 8527 7320 6f6e 2074 0300                 .'s on t..

Reimar's commit message says it should 

http://archive.org/download/FfmpegTest/BCSPA039_pre.mov
http://samples.ffmpeg.org/MPEG2/subcc/Test%20for%20Quicktime%20608%20CC%20file.mov

contain a stream flagged "eia_608" with packets that look like that:

00000000: 0000 000a 6364 6174 8080 0000 000a 6364  ....cdat......cd
00000010: 7432 8080                                t2..

That looks very different from the WTV packet format, there may be something
wrong.

Regarding the issue of this thread, I now believe that CEA-708 really
deserves a different codec-id. I will try to get something working with the
samples I have and MPlayer's code.

Regards,

-- 
  Nicolas George
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