[mythtv-users] Re: mpeg2 playback performance issue makes no sense

[Grant Edwards]

On Tue, Oct 12, 2004 at 07:54:35AM -0500, Michael J. Lynch wrote:

> First I ripped a DVD and used mplayer (via "watch videos") to
> playback the ripped VOB(s).  I checked CPU idle time and it
> was about 70% idle.

[...]

> I went to "watch recordings" and sure enough the VOB file was
> watchable under the name of what I had recorded.
> 
> Now this is where it get's weird.  The playback was skipping
> and generally acting like there was not enough processor to do
> the playback, so I checked it out.  Sure enough, playback
> using Myth's internal playback was pegging the processor.

Yup.  Works that way for me too.  When running Myth on my
laptop, it can only play MPEG2 files (these happen to be
created by Myth/PVR-350) at a couple frames-per-second.  OTOH,
mplayer and Xine play the files fine at full frame-rate.

> First, is the test methodology I described valid?

I believe so.

> If so, what could account for the large difference in
> processor usage between "watch videos" and "watch recordings"
> playing the same file?

AFAICT, Myth's SW decoding/playback functions are an order of
magnitude slower than those used by xine and mplayer.

> My system is 733 PIII with 384M, FC1, and Myth 0.16.

Mine was 600MHz PIII, 128M, KnoppMyth (Myth 0.16).

-- 
Grant Edwards
grante at visi.com