[mythtv-users] HD-PVR playback--high CPU usage

[Brian Wood]

On Thursday 25 March 2010 07:41:06 am Zach C wrote:
> On Thu, Mar 25, 2010 at 9:32 AM, Brian Wood <beww at beww.org> wrote:
> > On Thursday 25 March 2010 07:22:26 am Zach C wrote:
> >> Hi,
> >>
> >> I'm having trouble playing back recordings from my Hauppauge HD-PVR.
> >> The CPU on my Pentium dual core frontend is pegged and playback is
> >> unwatchable.
> >>
> >> What is weird is that I can play back 720p h.264 torrented video files
> >> with no problem.  In that case playback is perfect and cpu is probably
> >> around 30%-50%.  I would think the 720p h.264 video coming from the
> >> HD-PVR should be roughly equivalent to the video files.  I don't
> >> understand why the system can't handle it.
> >
> > Files acquired by "unofficial" means are often encoded at low bitrates.
> > If your HD-PVR recordings are at a significantly higher bitrate this
> > might explain things.
> >
> > Are you using VDPAU? Pure software decoding of HD recordings does take a
> > lot of CPU.
> >
> > What (if any) de-interlacer are you using?
> >
> > Playback with Myth's internal player does take more CPU than some other
> > methods, since it is doing more (checking the DB for commercials etc.).
> > Have you tried playing the recordings back with some other program?
> >
> > You might try a simpler playback profile (Slim?).
> 
> No--not using VDPAU, but nor am I using it on the 720p mkv files
> either.  Playback profile is the same for recordings and mkvs.  In
> fact, as far as I can tell everything is the same between the two,
> configuration wise. Also the mkv files are being played with the
> internal player, so hopefully that is equivalent to recording
> playback.
> 
> I will muck with the HD-PVR's bitrate and see if that helps, but I've
> already got it ratcheted down pretty low.  I'll check and see what the
> approximate bitrate is on the mkv files is.

Files acquired by torrents are often encoded poorly, often by rank amateurs 
(though there are exceptions).

I'd guess you will find the files that play well are at a much lower bitrate 
than the HD-PVR recordings.

Check your RAM usage as well as CPU, if you are hitting swap that will slow 
things down, obviously.

There are some sites with test video files recorded at different resolutions and 
bitrates. You might try those, thus reducing the variables involved.