[mythtv-users] PVR350 TVOUT

f-myth-users at media.mit.edu f-myth-users at media.mit.edu
Tue Jan 19 08:05:56 UTC 2010

    > Date: Mon, 18 Jan 2010 19:39:28 -0500
    > From: "Michael T. Dean" <mtdean at thirdcontact.com>

    > Correct.  But, really, the PVR-350 decoder is useless, as with even
    > almost-modern hardware, decoding 9.6Mbps 480i60 or 576i60 MPEG-2 in
    > software on a general-purpose CPU is trivial.

    > OK, actually, "useless" isn't the right term.  The PVR-350 decoder
    > hardware is an anachronism.  It's not 1999, anymore.  :)

What about handling closed captions?

My understanding is that the 350 can only pass embedded VBI CC using
its mpeg decoder and not via the X framebuffer.  But the PVR's use a
nonstandard VBI embedding, so while one can pass CC into the stream
and back out to the TV that way, it's not clear to me at all how this
would work if using a 350 FB or a normal video card---something has
to take that nonstandard encoding and make it available for Myth's
internal player, so it can superimpose the captions on the screen
instead of the TV doing so from line 21 data.

What's the toolchain here?  Is it automatic, or do people have to set
up user jobs to run cc-srt (or whatever) over the stream?  Does it
work in LiveTV as well?  (LiveTV CC seems to imply a toolchain that
can do continuous conversion on the file being generated, or native
understanding in Myth's internal player of PVR-style VBI CC embedding;
I don't know if that exists sans 350 support.  The last time I tried
to research this topic, I found too many suspiciously ancient and
contradictory sources.)

In other words, you've said many times that you regretted buying your
350, but for SDTV people, it serves a very definite need and one that
has some unique features---and not just CC either; witness WSS in PAL/
SECAM, etc.  Being able to have built-in alternatives for those needs
that are as painless as using the 350 seems important if you're going
to dismiss the 350 as "useless"; can you explain how to get equivalent
functionality?  This is something that many people decommissioning
350's will need to know, and the whole story isn't immediately obvious
to me.

[I hate to keep hammering on this issue, but for some people, lacking
CC support means they might as well not bother trying to watch TV at
all.  Like many accessibility issues, it often seems trivial to those
who don't need it and often ignored, but is absolutely essential to a
small population.]


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