Comcast/Mythtv (OT?)

[Jarod Wilson]

On Mon, 2008-11-24 at 10:47 -0500, Dan Ritter wrote:
> On Mon, Nov 24, 2008 at 10:09:42AM -0500, Bill Bogstad wrote:
> > This is slightly off-topic, but does involve Linux...
> > 
> > * What are my options for encrypted QAM and Mythtv?  (Note: I'm
> > currently SD only and HD would be nice, but not a requirement.)
> 
> The Hauppauge HD-PVR is currently being sold, and has
> preliminary (i.e. patch-the-source) support in MythTV.
> 
> That pulls component signals out of the cable box. It's
> expensive, and the encoding is apparently difficult to decode
> without either serious CPU utilization

The HD-PVR can be configured such that it isn't so bad for many systems
already capable of mpeg2 HDTV playback. The default encoding settings
are 13.5Mbit streams, constant bitrate. That kicks underpowered systems
in the teeth. If you go to variable bitrate and a slightly lower max
bitrate, even a mere 2GHz machine w/Intel graphics can play back the
resulting recording. (yes, I say "mere" somewhat tongue-in-cheek). My
2.16GHz Core 2 Duo, Intel X3100 graphics Dell Studio Hybrid can play
back 10Mbit VBR recordings from the HD-PVR just fine, chokes on the
13Mbit CBR stuff. Not sure what the actual thresholds are, haven't
played w/my HD-PVR all that much.

At the moment, the HD-PVR's recordings can't be decoded in a
multi-threaded way, i.e., it has to be done entirely by one cpu core.
Once that's remedied (not sure on ETA), it should be less painful for
multi-core systems to decode it. That, and as Dan mentioned, hardware
offload is slowly becoming a possibility too...

--jarod