On Sat, Apr 17, 2010 at 05:27:30PM +0300, Sviatoslav Chagaev wrote:
quoted text
> DELL Latitude D400 laptop reporting in!
> 
> At first, I accidentally compiled the kernel without the GEM option, as
> a result, when I ran X, the screen just went black, and even when I 
> killed the server through ssh, the screen never recovered.
> 
> Everything seems to be working ok.
> 
> I played with Mplayer a bit and noticed that the good old 'stroboscopy'
> video was still there. I.e. when there is a lot of motion, the video
> kinda like slows down periodically (each second or so) and then goes to
> normal, possibly dropping some frames or effectively dropping them by
> playing the frames which are being late very fast so that the brain
> doesn't have a chance to perceive them. Then it occured to me to try
> Mplayer's -nosound option, and the video then played real smoothly.
> Then I `pkill aucat` and tried playing the video again, it was just as
> smooth as with '-nosound'. Here's a video which demonstrates the
> effect: (I suggest watching it with aucat not running, since if it does
> the same effect for you, you won't be able to see the difference)
> 
> http://yy.lv/download.php?f=122601
> 
> first, the video is played with mplayer's -nosound option
> then, `aucat -l` is started and the video is played
> finally, `pkill aucat` and the video is played
> 
> This problem, 'stroboscopic' video when there's a lot of motion, has
> been bugging me for a long time now, as long as I can remember in fact.
> So I can't really tell whether earlier it was due to bad performance of
> the video drivers or because of aucat, since it never occured to me
> before to try -nosound.
> 

This effect is caused by the clock resolution not being high
enough.

Mplayer is using the sound card clock ticks (determined by
the audio block size) to sync video to audio, and the
default block size of aucat is too large.

Could you confirm that video is smooth if you
use ``aucat -l -z 480'' ?

-- Alexandre