[mythtv-users] Fwd: Problem with XvMC being slow

Steve Malenfant smalenfant at gmail.com
Mon Jan 16 22:24:09 UTC 2006


The problem I've seen on my system are :

- Use Video as Time Base (experimental).  For some reason mine was
checked and sometime it would work just fine.  Disabling that solved
my problem.
- Not using Alsa drivers, every time a new kernel gets out you have to
go get the alsa driver, pain that it doesn't upgrade on it's own.
- Ring Buffer Size is a problem when too high on my backend, looks
like every few seconds my frontend would have to wait for I/O from the
backend and pause frames for a few milliseconds.  When you check with
"top" and you see "wa" using CPU time, that's a problem.
- My 100$ PC from fry's (Duron 1600) with PCI MX4400 is enough to play 1080i HD.

Steve M.

On 1/15/06, Jerry Rubinow <jerrymr at gmail.com> wrote:
> On 1/7/06, Jerry Rubinow <jerrymr at gmail.com> wrote:
> >
> > On 1/6/06, Steve Adeff <adeffs at gmail.com> wrote:
> > > On Friday 06 January 2006 00:05, Jerry Rubinow wrote:
> > > > On 1/5/06, Jerry Rubinow < jerrymr at gmail.com> wrote:
> > > > > On 1/5/06, Joseph A. Caputo <jcaputo1 at comcast.net> wrote:
> > > > > > On Thursday 05 January 2006 1:21, Jerry Rubinow wrote:
> > > > > > > When using XvMC to play back video, CPU usage is low (30% for HD,
> > 10%
> > > > > > > for SD), but the video plays back slower than realtime.  I'm using
> > an
> > > > > > > Nvidia 5200 card, with driver version 7667 (although I've tried
> > every
> > > > > > > version up to the current 8XXX).
> > > > > > >
> > > > > > >  Is there anything I should check?  Anything obviously wrong from
> > the
> > > > > > > following details?  Or is this the XvMC slowdown I've read about?
> > > > > > > What are my options for fixing this?
> > > > > >
> > > > > > I could be way off base on this, but something in my memory is
> > nagging
> > > > > > me... something about maybe Nvidia's XvMC not supporting/performing
> > > > > > well at certain resolutions?  Have you tried changing your
> > horizontal
> > > > > > resolution to something smaller, like 1024?
> > > > >
> > > > > No, but that's a good suggestion - I'll try it tonight.  Thanks.
> > > >
> > > > No luck.  I tried setting both X and the GUI setup in myth to 800x600
> > > > and it's still slow playing HD.  Not stuttering, just slower than real
> > > > time.  I didn't mention before, but I'm using pretty much a straight
> > > > following of Jarod's guide with FC4, 2.6.14, on a P4 2.8.
> > > >
> > > > I'm so close to having beautiful HD playback, can anybody suggest things
> > to
> > > > try?
> > >
> > > poney up for a faster processor? I know its prbly not an optioin, but with
> > a
> > > 3.0 or 3.2GHz cpu you'll be able to play back HD without XvMC.
> > > Does OpenGL sync work with XvMC? I dunno, but might be worth a try. Also,
> > try
> > > disabling any deinterlacing? Oh, what about audio buffering options, have
> > you
> > > played with those?
> > > Also, don't forget you have to restart mythfrontend everytime you make one
> > of
> > > these changes. minor bug...
> >
> >
> > I'm already at the fastest processor a Pundit will accept, so I'd have to
> > scrap my whole nice form factor frontend to do that.  I'm using OpenGL sync,
> > and deinterlacing is already disabled.  I haven't played with audio options
> > at all, but I don't think that can be it, since if I turn off XvMC, NTSC
> > plays back fine, but with it on, it plays back slow (not stuttering, just
> > slow-mo).
> > I'm out of town this weekend, but when I get back, I'm going to try
> > compiling mplayer with xvmc support and see if that has problems playing
> > back too.  That will at least either eliminate myth from the equation or
> > point to myth as the culprit.
>
> For anybody following this thread, increasing the ringbuffer size was
> what finally fixed this problem.
>
> -Jerry
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