[mythtv-users] N00b question about video playback

chris at cpr.homelinux.net chris at cpr.homelinux.net
Wed Jul 20 15:46:43 EDT 2005

On Wed, Jul 20, 2005 at 09:26:30AM -0400, Erich Beckmann wrote:
>   When I try to playback a lot of my movie files, the playback is very 
> jerky. Is there somewhere I can look to tweak the settings of Mplayer to 
> get the playback to be smoother? OR What is the recommended way to go 
> about configuring the string to launch Mplayer?

You should probably start by clearly identifying the bottleneck.  The 
big four on a MythTV system will be hard drive speed (transfer rate, 
DMA), network speed (on split front/back systems), video output limits 
and CPU usage.

For example, instead of running TV capture and playback at full screen 
sizes on high resolution, make sure the recorder is idle and then do a 
playback into a 320x200 window.  If the playback stops stuttering then 
your hard drive and/or network are keeping up and the problem is in 
computation.  If it still stutters then you have a transport problem.

Of course the resolution of the display also plays a role, but the 
difference can sometimes be counter-intuitive.  One of my front-end 
machines uses an LCD display rather than TV-out.  On that machine I get 
*far* better performance if I run MythTV at 1280x1024 resolution than 
at 640x480 resolution.  I assume this is because the LCD has to display 
at its native resolution no matter what the computer generates, and the 
video card's hardware accelleration is more efficient at scaling the 
image than the LCD is.

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