[mythtv-users] High-Definition Playback performance data

[Brian Foddy]

On Sunday 03 April 2005 11:48 pm, Brad Templeton wrote:
> On Sun, Apr 03, 2005 at 08:51:50PM -0500, Pete wrote:
> > I'd like to know what I can do get that kind of performance. I've got an
> > Athlon XP 3000 (512 MB RAM) and an FX 5200 (AGP) running myth .17 and
> > FC3 (everything is from atrpms) where HD is close, but not quite. After
> > a lot of hacking to get the channels to work, it finally comes up, but
> > I'm getting lousy performance, with a lot of audio buffer underrun's
> > (using spdif through an on board nvidia audio chip) and video stutter's.
>
> We should try to build a list of all the things that can go wrong in
> making HD work smoothly.  There are many.
>
> They include:
>
>
>     a) Right drivers for card with your kernel
>     b) Proper AGP bus speed and AGP interface driver in use
>     c) Proper user of openGL sync for retrace
>     d) Proper settings for deinterlace and, if used, xvmc
>     e) Proper sound settings and handling of 5.1 sound and multiple streams
>     f) Real time scheduling of playback thread
>     g) Making sure disk or network speed is adequate
>     h) Nothing else sucking up CPU on the machine
>
> And of course having the right cards and memory itself.

I have found in my set that raising the write internal buffering helps too.
I like to bump the standard write buffer to 8MB, and HD to 16MB, each
4x what the current code is at.  Seems to help reduce Buffer Overflows
when there are a lot of streams all writing to the same network nfs drive
(even for gigabit networks).  NFS is not real efficient at streaming large
volumes of data.