[mythtv-users] VDPAU playback issues

Mark Greenwood fatgerman at gmail.com
Sun Nov 4 22:01:18 UTC 2012

On Monday 05 Nov 2012 07:18:38 HP-mini wrote:
> > Thanks. I read on the wiki that for glitch-free playback you should
> > only use the 295 series drivers, as something changed in the 3xx
> > series which meant that glitch free would not work. That's why I'm on
> > the 295 driver still. I've also tried the VDPAU Normal profile but it
> > has made no difference to this problem.
> > 
> Haven't noticed this problem (yet).. 
> Sounds like a composite effects interaction (unity compiz etc).

Composite is disabled, otherwise I'd agree with you :)

> > 
> > So from the replies I've had there doesn't seem to be anything
> > specifically wrong with my mythtv setup, which is a releif :). This
> > problem is specific to certain mkv files, and those same files also
> > play jerkily in mplayer (which also uses ffmpeg) so I don't think it's
> > actually a mythtv issue.
> > 
> >  
> > 
> > Does anybody know of any tools which could look for problems in the
> > files I'm having trouble with? I've tried loading them into avidemux
> > but that loads them fine. I'm just intrigued as to why some files are
> > maxing out the CPU and some apparently identical ones are not.
> > 
> If your vdpau decoder does not support your media format then CPU decode
> is used.
> MPEG4-ASP DivX Xvid are only supported from 2xx series vdpau.
> The 1st gen ION & 8400/9400/etc have some resolution
> "no-go-operating-areas"

OK this is MPEG-4 AVC and it must be using VDPAU because once it has settled down it plays fine with only 5% CPU usage, and other files encoded at the same resolution play perfectly. It's just that initial burst of 100% CPU at the start that seems to be the issue.

Using mediainfo I can't see any difference between the bad file and another one that plays perfectly, nor is there any difference in the output when playing them through mplayer with the verbose option, and yet the first one glitches at the start every time. Unless the glitch is actually encoded into the video itself, which is something that has only just occurred to me... :o

One final thing I want to check though - at the start of playing any high-resolution video, there is a huge spike in CPU usage and mythfrontend is the culprit. What might it be doing during those first few seconds that could cause that? (If it's normal I'll just put this one down to a few bad video files).



> You could probe the files with ffprobe or mediainfo.
> The nVidia driver readme tables the vdpau limitations in appendix A.
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