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

[Jarod Wilson]

On Thursday, Sep 18, 2003, at 09:10 US/Pacific, Brandon Beattie wrote:

> 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).

Gotcha. This is all starting to make more sense. I spent a goodly 
amount of time browsing avsforum today...

>> 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.

It's a mix, actually. The HD channels are mostly 100-119 or so, along 
with ESPN out on 173. I'm not certain where the HBO and Showtime HD 
channels are. 0-99 is all NTSC, 120-172 NTSC, 174 and up NTSC (there 
are channels ranging all the way up to like 950, like music-only 
channels, a bazillion ppv channels, etc; I think I get at least 300 
channels with my package).

>> 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.

Both to save disk space and to save wear and tear on the disk... I 
think that would definitely be a good thing...

--Jarod

-- 
Jarod C. Wilson, RHCE

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