[Matroska-devel] New Matroska field: extra broadcast data

Jerome Martinez jerome at mediaarea.net
Thu Sep 24 20:00:07 CEST 2015


Le 23/09/2015 18:13, Steve Lhomme a écrit :
> In addition to close caption, broadcasting often carries data in some
> non displayed pixels, especially in analog videos. We should be able
> to store those invisible information in the container as well.
>
> The first that comes to might is Teletext in Europe. There might be others.

I think to:
- VBI raw content (dump of non visible part of a video stream, and 
should sometimes not be lossy compressed, so not in the compressed video 
stream directly), which can contain SMPTE ST-12 timecodes (real time 
codes, not timestamps ;-) ), CEA-608 captions...
- VANC (SMPTE ST-291, we must be careful because there are 10-bit / 
synchro bytes / checksum "options", because MXF uses 8-bit +no synchro 
bytes + no checksum , GXF uses 10-bit + no synchro bytes + checksum, LXF 
uses 8-bit + synchro bytes + checksum, if we define VANC in Matroska we 
need to say how we transport it), which can contain SMPTE ST-12 
timecodes, CEA-608 captions, CDP, Bar data, Teletext (WST actually), 
Acquisition Metadata (SMPTE RDD 18)...
- CDP from a serial link (captions only).

BTW, same issue with "Teletext": Teletext can contain a programs list + 
subtitles in the same track.

>
> Given it's in the video frames it should probably be a kind of
> track(s). We already extract the closed caption. We could extra some
> others with different "codec" and/or keep the rest of the data raw to
> be handled by other processes, outside of the scope of Matroska.
>

Isn't TrackType = 3 (Complex) enough for that?
and we try to define C_VBI, C_VANC, C_TELETEXT... codec identifiers.


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