[mythtv-users] How to improve 720p playback (1080i ok)?

Jerry Rubinow jerrymr at gmail.com
Sat Dec 4 20:48:43 UTC 2010


On Sat, Dec 4, 2010 at 3:20 PM, Taylor Ralph <taylor.ralph at gmail.com> wrote:

> On Sat, Dec 4, 2010 at 3:13 PM, Jerry Rubinow <jerrymr at gmail.com> wrote:
> > On Fri, Dec 3, 2010 at 8:45 AM, Jerry Rubinow <jerrymr at gmail.com> wrote:
> >>
> >> On Fri, Dec 3, 2010 at 2:28 AM, Raymond Wagner <raymond at wagnerrp.com>
> >> wrote:
> >>>
> >>> On 12/3/2010 00:34, Jerry Rubinow wrote:
> >>>>
> >>>> With more investigation, I've found mpeg 480p, 720p and 1080i all play
> >>>> back ok.  It is H264 720p which does not.  Any ideas what to look
> into?
> >>>
> >>> 720p60 means these are HDPVR recordings? What bitrate do you have it
> set
> >>> to?
> >>
> >> Yes.  The mpeg recordings are all HDHomerun, and the H264 720p60 is from
> >> the HDPVR.  It's set to whatever the default is - I've never changed it.
> >>  I'll try changing the bitrate and see what happens.  I do observe
> though
> >> that the CPU hovers in the low 30 percent range when playing back.  So I
> >> don't understand the reason for the pauses, if it's caused by too high a
> >> bitrate.
> >
> > I lowered the bitrate down to 2000 in the profile and recorded a show,
> but
> > it still has the same problem.
> > To reiterate, 720p H264 recordings from the HDPVR exhibit pauses during
> > playback.  The log shows that frames are repeatedy being dropped because
> the
> > audio is ahead of the video.  I have no problem with 720p or 1080i mpeg
> > files from the HDHomeRun.  Playback is under mythfrontend compiled on a
> > Window box with ION video.  CPU usage during playback is low (around the
> low
> > 30s percent).   Lower than with the mpeg playback.
> > I tried forcing the NVideo vsync setting off, didn't help.  Tried
> different
> > recording bitrates, as mentioned, didn't help.  Playback is configured to
> > use Direct3D / ffmpeg.
> > Can someone fill in any details about how mpeg decode differs from H264
> > decode in myth?
> > -Jerry
>
> It would be much more helpful if you posted a log with the video in
> question playing with the -v playback,timestamp options.


Indeed, enclosed is the log of a session.   At the user end, I started MFE,
told the recording to play, immediately hit Esc to clear the OSD, waited a
few seconds to observe the undesired behavior, and exited playback and then
MFE.

-Jerry
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