[mythtv-users] Is the pchdtv card looking good?

[Brandon Beattie]

On Thu, Sep 18, 2003 at 12:27:26AM -0700, Jarod C. Wilson wrote:
> Never heard of them sending only one rez and audio track, or never 
> heard of them putting NTSC and HD on distinct channels (even when they 
> are the same show)?

By NTSC on HD, I mean that they have taken their NTSC signal and
transcoded it into 480i or 480p ATSC and put that into a subchannel
(Often in realtime).

> Aha. This further leads me to believe Comcast breaks stuff up. ABC is 
> channel 4, ABC-HD is channel 104. PBS is channel 9, PBS-HD is channles 
> 108, 109 & 110. ESPN is channel 30, ESPNHD is channel 173, etc, etc.

I'm not sure how they do things, If your HD tuner also does NTSC
tuning/display, you may be getting channels sub 100 are NTSC (Real NTSC)
and over 100 are NTSC transcoded to ATSC/HD in realtime, or true HD
channels.

> So when you are capturing HD channels w/the pcHDTV in mythtv, is it 
> using dtvdump for the actual capture, then picking out the subchannel 
> to play back?

It grabs data from /dev/video32 (The device for the pcHDTV card) and
puts it into the mythTV video buffer, either for livetv, or for writing
it to disk.  But yes, same idea as used in dtvdump.  Possibly in the
future though, spliting the full dump up may occur so we only save or
record 1 of the several subchannels, and throw everything out.  Possibly
even transcoding from mpeg2-ts to mpeg2-ps in realtime to get rid of the
redundant data in the ts (transport stream) to save disk space.

--Brandon