[mythtv-users] Myth/HDHR impressions & issues

Mike Perkins mikep at randomtraveller.org.uk
Fri May 29 17:39:09 UTC 2009

Alan Marchiori wrote:
>>> I am using QAM sources from the cable co.  I wonder if that has
>>> anything to do with it?  I know the quality is not as good as ATSC,
>>> but I get more channels this way.
>> I'm pretty sure that this doesn't haven't anything to do with the HDHR as
>> commercials are flagged after they are recorded and the HDHR simply receives
>> the stream from the broadcaster without any modifications.
> I agree, but I think it may actually be possible.  The ATSC stream is
> whatever the broadcaster sends out (good quality).  The QAM stream is
> re-encoded by Comcast and sent over their network.  From my limited
> knowledge on the subject I believe comcast applies much more
> compression than the original stream had (to save bandwidth at the
> cost of image quality).  My theory is that this extra compression
> makes comm flag unhappy.  If the original poster also uses QAM my
> theory holds, for now, if they use ATSC we can toss that theory out
> the window.
You may also get a less consistent stream. I know other people here talk about 
framerates/bitrates/transmission standards/whatever being changed on the fly. If 
the ad is transmitted in a format that's not the same as the show the code may 
have problems detecting it, perhaps.


Mike Perkins

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