[mythtv-users] XvMC at 1080i output

[Jarod C. Wilson]

On Oct 3, 2004, at 10:49 PM, Mr Joe Barnhart wrote:

> I'm going nuts trying to get smooth playback of HDTV
> files captured at 1080i and 720P.

I feel (some) of your pain. :-)

> My setup is a
> KnoppMyth box (R4V5) with Abit NF7-M m/b with onboard
> GeForce 4MX graphics, Athlon 2800+, 1G RAM,
> 200G+250G+250G disk (XFS+LVM).  I'm using a Pioneer
> rear-projection TV with a VGA input locked to 1080i.

Fedora Core 2, custom pcHDTV-patched kernel, GeForce FX 5200, Athlon XP 
3200+, 512MB of RAM and a Panasonic RPTV, feeding both 540p and 1080i 
modes (540p for GUI & standard-def programming, 1080i for HD 
programming). You didn't explicitly mention it, but I presume you're 
running the latest nVidia driver like I am.

> The video output from this combination is unwatchable.
>  With 720p source material, the image flashes back and
> forth in time rapidly, "stuttering" in video.  At
> times the flashing back and forward stops, but the
> video slows down and the audio has gaps.  This is with
> straight XvMC with no added filtering.

This sounds *very* similar to what I see w/720p sources (which happen 
to play just fine w/mplayer and on other people's boxes). Your debug 
output has some of the same curious lines I saw that Doug Larrick 
didn't see when playing back a problematic clip I'd posted. I'm 
currently recompiling with some different options to see if some 
particular combinations are causing the problem, because I've tried 
just about everything else. There are two threads on the dev list in 
which this has been discussed, you might give them a look also.

> With 1080i source material, the A/V streams are
> smooth, but the video resolution is reduced.  It
> appears to be something like 500 lines instead of
> 1080.  The jaggies are so bad that it makes it
> difficult to watch a football game, because of the
> artifacts on the lines on the field.  If I use the
> skip back or forward buttons, the image hangs, forcing
> me to restart gdm.

That's an odd one. I have zero issues with any 1080i channels now. (Had 
some minor audio initialization problems that don't exist once passing 
raw ac3 to my amp). Are you sure you're running a 1080i modeline and 
not a 540p one? That could account for both the lines and the severe 
jaggies. No clue on the restarts.

> I tried using Xv, but unfortunately my system just
> isn't up to decoding and playing 1080i streams in
> software.  I can't get smooth playback, or continuous
> audio.  The 720p stream plays better but it also
> suffers from reduced resolution and isn't up to HD
> quality.

I'm not using XvMC at all, with a deint filter enabled, and my 3200 
sits between 70-80% utilization.

> I am using all stock software from the 0.16 release.
> I'm a little surprised to find that XvMC does not work
> as expected.  Am I doing something obviously wrong?

Probably not. I can't find anything I'm doing obviously wrong either, 
and I've been digging into this for a while now.

> I have attached a log from the frontend during playback.
> I'm searching for suggestions here.  I'm so close,
> but this just isn't watchable.  I'll consider ANY
> modification to the system (i.e. dump the video,
> faster processor, etc.)  My only unchangable item is
> the TV set.

Hold that thought for the moment. I don't think a jump to 3200 or a 
switch up to a GeForce FX 5200 is going to make the difference just 
yet. You should probably join up w/the thread in the dev list, I'm 
actually somewhat happy to find I'm not the only one with the 720p 
problem. :-)

Odd coincidence that we both use Athlon processors though... Once my 
current recompile is complete and I can run through a few tests, I'll 
be reporting back...

-- 
Jarod C. Wilson, RHCE
jcw at wilsonet.com

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