[mythtv-users] VDPAU field report

Seth Daniel mythtv.org at sethdaniel.org
Sat Jan 31 06:12:21 UTC 2009


Thanks Yeechang, an interesting report.

On Fri, Jan 30, 2009 at 09:32:32PM -0800, Yeechang Lee wrote:
[...snip...very interesting report...]
> 1. Playback with the Advanced 1x deinterlacer is perfect, with no skips
> at all in the mythfrontend log output (except maybe during OSD fading)
> (<URL:http://pastebin.com/f1e3299c6>); Advanced 2x exhibits the
> occasional brief skip that's hardly visible in the actual
> playback. CPU usage is 2-5%, with occasional jumps to
> >10%. But . . .
> 
> The above holds only for the first playback. Once exiting, all
> subsequent playbacks until telinit 3/rmmod nvidia/telinit 5 skip
> continuously, regardless of Advanced/Temporal 1x/2x
> (<URL:http://pastebin.com/d3303f5dd>). Bob 2x is relatively
> OK. Switching between RTC and OpenGL vertical sync does not change
> this behavior.

FWIW, I don't have this particular issue.  I have been using OpenGL
vertical sync for as long as I can remember.  I have not tried RTC in
some time.


> 2. A more serious issue is that I can reliably hang the frontend by,
> during playback, bringing up Program Finder, Program Guide, or
> Upcoming Recordings. Ctrl-Alt-Backspace does not work and any SSH
> session into the frontend hangs too. Magic SysRq does work,
> fortunately.

I have noticed this issue, but I can ssh in and kill the frontend no
problem.  I also have my remote's power button setup to kill the running
frontend if I press it.  This works just fine also.  So I have the
hanging issue, but it is not a 'hard' hang.


> 3. A third, minor, peculiarity is that VDPAU output does not seem to
> be affected by my specified gamma settings, whether in xorg.conf or in
> nvidia-settings, so the video is far too dark for my tastes.

I cannot comment on this.

Related to VDPAU and of interest to those of us with interlaced
televisions is the following:

In the U.S., of the major stations, I believe only NBC and CBS and at
least some PBS stations are interlaced.  For those of us that want to
play 1080i material at 1080i we typically have to use a deinterlacer,
like Bob, and patch our mythtv builds (I don't wish to go into all the
gory details here.  Anyone that interested can simply go to
gossamer-threads and search for my e-mail address).  All of this is done
to keep the video from horrible tearing.  

With VDPAU I notice that NBC seems to play just fine.  I watched 6 or 7
minutes of 'The Office' and an equal amount of time of '30 Rock' and I
didn't notice any tearing.  This is with no deinterlacing and the 180.25
Nvidia driver.  *However*, CBS is just as awful as ever.  Lots of
tearing during the first 30 seconds of an episode of CSI: NY.  So along
with the VDPAU -fixes patch I still have to patch my mythtv to accept 2x
refresh rate with interlaced material so that I can run Bob 2x.  FWIW, I
see the same results using the VDPAU mplayer (using the Nvidia patches).

That said, the VDPAU Bob 2x is fantastic.  The video is very smooth and I
use less than 10% of total CPU (I have a dual CPU combined fe/be setup).
Compare that with 60-80% of total CPU w/o VDPAU.  Now I just have to
decide how to use all my new CPU time!

I tried the temporal and the advanced, but Bob seemed to be the best for
my setup.  Temporal 2x and, I believe, Advanced 2x I found to be
unusable.

-- 
seth /\ sethdaniel.org


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