[mythtv-users] HD-PVR clip trials with 5.1

Yeechang Lee ylee at pobox.com
Wed Oct 1 18:35:02 UTC 2008

I have tested, on my Pentium 4 3.0GHz frontend using MythVideo, the following 5.1-encoded
720p HD-PVR clips that have been posted to AVSForum:
(maximum 13.5Mbps encoding) and
(unspecified, but my guess is 6Mbps). I use 0.21-fixes with the
and Mark Kendall's (which I don't think would make a difference as I
don't use the OpenGL output anyway) patches, with the Standard
decocer, xv-blit renderer, and RTC timer settings.

The baseball clip has excellent video quality, as expected. As with
other high-bitrate clips I've tested, it "almost" plays; that is,
0.5 to one second or so of smooth playback (a bit longer when there is
little motion on the screen, such as during the instant replay early
on) is interrupted by briefer blips of 'NVP: Waiting for prebuffer'
messages. top says mythfrontend is using 75-99% of CPU averaging at
85-90%. That said, the performance seems better than other, non-5.1
13.5mbps clips I've tested, so it seems that passing the AC3 track
straight through to the receiver does help ease the playback load

The _Chuck_ clip plays with no problems whatsoever, even with a
mythcommflag job running in the background. The picture is grainier
than the baseball clip (but then the source is grainier, as I know
from watching the show), but is certainly more than usable. I'd quite
happily encode recordings at this bitrate until I get a faster

Two things I have not yet tried:

* Playing "real" encodings I've made myself from within the actual
  internal player, as opposed to MythVideo's internal player. It's
  possible that with a proper seektable a higher bitrate could be
* The CoreAVC
  indicates issues with patching 0.21-fixes; anyone with luck with this?

Yeechang Lee <ylee at pobox.com> | San Francisco CA US

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