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

[Zach C]

On Thu, Mar 25, 2010 at 9:59 AM, Brian Wood <beww at beww.org> wrote:
> 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.

Actually I'm finding the torrents to be of extremely high production
quality--they look gorgeous and are flawless, which is why I thought
they'd serve as a good baseline for what my frontends can handle.  Not
sure about the bitrate on the HD-PVR vs torrents, though.  Will check
that.

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

Yeah--a valid point.  I've checked swap usage, which is staying at 0,
so I'm fine there.

> There are some sites with test video files recorded at different resolutions and
> bitrates. You might try those, thus reducing the variables involved.
Good point.  The mythtv wiki links to a few I think.  Will try those.


-- 
:wq!