Re: Performance issue

On Sat, 4 Mar 2006 22:49:28 +0000
David Mulcahy <[email protected]> wrote:

> I am having a performance issue with mplayer using mga_vid in debian stable.  
> Looking at all the advice online seems to indicate that -vo xmga will give 
> the best performace.  However I have been seeing a slight jerky picture when 
> the camera starts panning across a room or scenery.

It's actualy a problem of the codec eating more cpu time. When
you have a lot of movement, then the codec needs to access more of
the picture in a way that will most probably destroy all advantage
you get from L2 cache.

>  I started adjusting lots 
> of thinks to rectify this (hdparm upgrading kernel and debian to unstable, 
> tweaking things) but what seems to work best is the following command.
> 
> mplayer -ao alsa -channels 2 -vo xv -dr -double -dvd-device /dev/cdrom dvd://1 

For me, using -cache 10000 mostly solves these issues.
If it's not related to cpu usage (have a look at the "suposedly droped frames"
counter), then -mc & co might be of use.

> I guess the question is why this works better because direct rendering is (as 
> far as i know) is more likely to work with xmga than xv, but in my case it 
> works with xv and again as far as i can tell doesnt work with xmga.

Hm.. dr is some kind of black magic. It only works in very special
cases and is silently disabled in all other. I haven't checked
the code myself so i cannot say whether mga should perform better or
not.

Just BTW: If you have a dual cpu machine, Xv will actualy give you better
performance than mga (around 20% or so) as it splits the load onto two
programs which are then able to use both cpus

> Now i thought I best check with the experts to see if I am in fact using the 
> best settings because I have a feeling that -vo xmga -dr should work and give 
> me better performance.  Am I right or do am I using the best way with -vo xv 
> -dr.

I'd need a -v log at least be able to say anything.

				Attila Kinali

-- 
心をこめて聞け心をこめて話せ