[mythtv-users] Myth, ivtv, and VBI. Is it possible?

Ian Trider iantri at gmail.com
Fri May 27 18:37:21 UTC 2005


> And there is another.  I explicity remember Isaac's response stating
> that myth will support ivtv cc when ivtv puts the data in the mpeg
> stream "where it belongs".

I had thought that the code has not implemented in Myth yet to display
closed captions from MPEG-embedded VBI data, but IANAD and so have no
idea.

> I believe the stream type may have something to do with it. MPEG-PS,
> MPEG-TS.  But I cannot yet understand what the difference is.  I've
> tried both on my box a while back, and didn't see any visual
> difference, but I've noticed my current setting (which I believe is
> DVD-Special something or other) seems to result in good video quality
> and minimal storage space.  I will check this out over the weekend and
> see what I can determine.

DVD-Special is esentially an Program Stream designed to automatically
conform to the DVD specs (I think NAV packets get inserted
automatically).

There is no visual difference at all between the various different
stream types; it simply affects the way the audio and video streams
are multiplexed together.

The README.vbi file says that CC data is only embedded in program
streams -- keep in mind all this is done in hardware, AFAIK -- but
since the Windows driver requires you to set (hidden) type 14
(Dvd-Special 2) to embed (with  a registry hack) cc data, I would
think it would work..

to check, capture some brief mpegs from a source known to have CC as
each stream type and load them p on a Windows box running the free
tool Restream -- the CC data is stored as 'user data', in the 'user
data' segment you should see random-looking trash if the CC has been
embedded.

Good luck,

-- 
Ian Trider
iantri at gmail.com


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