[mythtv-users] High-Definition Playback performance data

[Paul Leppert]

On 4/3/05, Brad Templeton <brad+myth at templetons.com> wrote:
<snip>
> 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.

Brad,  I think this is great.  Even better would be how one goes about
checking each of these items.  As a relative newbie, I'm not sure how
to *confirm* your list items a, b, e, f, and g.  I'll take a shot at
the others:

a) Right drivers for card with your kernel

Don't know how to confirm which one is loaded...

b) Proper AGP bus speed and AGP interface driver in use

Don't know.  Do you look in dmesg for this?  If so, what are we
looking for?  I can change my xorg.conf to use NvAGP = 1 or 2, but
don't know a way to confirm that it actually "took".

c) Proper user of openGL sync for retrace

Start mythfrontend with the "--verbose playback" option and redirect
output to a file.  Check for Open GL Sync messages (GLX SGI OPENGL
VSYNC or something like that) when a recording or live tv is played
back.  Possibly could also use glxinfo to check for the GLX SGI OPENGL
VSYNC as supported.

d) Proper settings for deinterlace and, if used, xvmc

These are set via mythtv in the settings->tv->playback screens
(deinterlace on the first and xvmc on the fourth or fifth, IIRC).  If
xvmc is set properly, the OSD will be black and white.  If xvmc
doesn't show up on the options screen, then it wasn't compiled into
the program.  If xvmc is used, the "filters" field (which can also be
used to set deinterlace) isn't used.  My personal opinion is that
kernel deint appears to give a better picture (in terms of motion
artifacts) than the others (including BOB).

e) Proper sound settings and handling of 5.1 sound and multiple streams

Not sure...  I am using ALSA:spdif for sound and I can confirm that it
works since my DD receiver switches to digital mode.  Not sure what
exactly to check here.

f) Real time scheduling of playback thread

Don't know...  Even after using chmod a+s on mythfrontend, my logs
still say that running as SUID would help, so don't know if I'm doing
this correctly or not (or even if that message is relevant).

h) Nothing else sucking up CPU on the machine

Check using "top" and confirm that mythfrontend and X are the top two
items (X may be lower if XvMC is used).  Remaining items should be
substantially less (not sure how to define "substantial"...).


Feel free to amend or add to my descriptions.  Anyone have a standard
place for this?  I'd be happy to add to the wiki if that's the right
place...

thanks,
phlepper

-- 
I hear and I forget. I see and I remember. I do and I understand.  --  Confucius