[mythtv-users] CONFIG_HZ setting in Linux kernel improved video playback for me
lists at wilsonet.com
Tue Feb 13 14:20:16 UTC 2007
> Like many MythTV Gentoo users I've built my own kernel. I have a
> fairly hefty FE/BE box (core2 6600, 1GB RAM, SATA 500GB drive, Nvidia
> 7600GT) that is primarily used for HDTV recording and DVD watching.
> The problem was I was still not seeing butter-smooth video,
> especially when the camera would pan across the screen. The problem
> was noticeable on both DVDs and HDTV sources.
> Reading up on the 2.6.20 kernel changes I found this i386 kernel change:
> 300Hz support. It is useful to have 300Hz support
> when doing multimedia work: 250 is fine for us in
> Europe but the US frame rate is 30fps (29.99 blah for
> pedants). 300 gives us a tick divisible by both 25 and 30,
> and for interlace work 50 and 60. It's also giving similar
> performance to 250Hz.
> I rebuilt my 2.6.20 kernel changing CONFIG_HZ from the default 100Hz
> to 300Hz and happily saw butter-smooth video playback for both HDTV
> and DVDs.
> Chances are this is my own fault as I'm sure the Gentoo stock kernels
> are already set to 1000Hz or 512Hz like FC kernels used to be. So as
> a tip, if you're trying various tweaks to improve your video playback
> and building kernels on Gentoo, don't forget to check your CONFIG_HZ
> setting as I forgot to.
250 and 1000 were previously your only choices unless you had some extra
patching. I'm currently using 1000Hz Fedora kernels without a problem,
but the real wave of the future it tickless kernels. Coming Real Soon
jarod at wilsonet.com
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