[MPlayer-users] Optimize video output from tv card

[Reimar Döffinger]

On Wed, Aug 26, 2009 at 11:44:27AM +0200, Michael wrote:
> Reimar Döffinger wrote:
> > Look at the "Cpu(s):" line in top, the 3rd line. It splits overall CPU
> > usage up.
> > The one you were looking at is all of those summed up as far as they can
> > be associated to MPlayer - which might include whatever e.g. the USB
> > driver is doing on MPlayer's behalf.
> 86.4%us,  3.4%sy,  0.0%ni,  0.0%id,  0.0%wa, 10.2%hi,  0.0%si,  0.0%st
> 
> Does that help?

Not really. Not without e.g. an oprofile trace. I'd recommend getting a
newer MPlayer version first though.

> >> The resolution and the framerate, however, is the same between the webcam
> >> and the TV card (604x480, 25fps). So, I thought, if displaying the webcam
> >> takes app. 50% of CPU usage, while displaying the TV card take 100%,
> >> mplayer seems to be doing more stuff ("internal processing") on the video
> >> data it gets from the TV card than from the webcam.
> > 
> > Well, you have specified 25 fps, but that doesn't mean that either of
> > them actually delivers 25 fps.
> > 
> 
> Well, if I don't specify the fps, mplayer states that it gets 25fps. If I 
> specify 15 fps, CPU usage goes down significantly (to app. 50%).
> 
> Taken together:
> TV card:
> -fps 25 (or no -fps):
> 86.4%us,  3.4%sy,  0.0%ni,  0.0%id,  0.0%wa, 10.2%hi,  0.0%si,  0.0%st
> -fps 15:
> 39.7%us,  0.0%sy,  0.0%ni, 57.6%id,  0.0%wa,  2.6%hi,  0.0%si,  0.0%st

It doesn't look like it, but there is a small chance something does some
busy waiting on the TV card and the TV card does less than 25 fps.
In that case there should be a rather sudden drop in CPU usage if you
slowly reduce -fps.
Also try some high value for -tv buffersize.

> Concerning "proper" hardware: You mean, graphics card, right? Unfortunately, 
> I don't have an option there. But I am fine with the ~50% CPU usage of the 
> webcam. Would be nice if the tv card would be there, too, instead of 100%.

No I mean plug the thing in a normal PC and see how it works.
If e.g. it uses 100% CPU in the latest i7 processor there is something
seriously wrong.