[mythtv-users] Upgrade old or cut my losses and buy new?

Steven Adeff adeffs.mythtv at gmail.com
Wed Mar 7 15:06:06 UTC 2007

On 3/6/07, David Murphy <dm1000 at gmail.com> wrote:
> matthew.garman at gmail.com wrote:
> > How bad is the "occasional jerk or stutter"?
> Well, 99.9% of the playback is smooth but this is one of those things
> where once you start to notice it you can't stop and it will slowly
> begin to drive you crazy.  For me, the libmpeg2 decoder seems to work
> much, much better than XvMC and uses substantially less cpu than XvMC
> which is counter to what I anticipated.
> I've been testing on a 1080i recording from my first gen air2pc card.
> It's from the local PBS station and the on-screen display for this
> station always says I am getting 100% signal.
> I've narrowed down a couple of scenes that can fairly reliably generate
> a visual stutter.  For example, there is a scene that involves a fairly
> quick horizontal pan across an audience of people.  Usually, once I
> queue up this scene I will see the stutter.  Then if I skip back a few
> seconds and play it again the stutter may or may not be there.  I
> haven't quantified it but let's say the stutter will occur at least 50%
> of the time that the scene is played but it will NEVER occur 100% of the
>   time.
> In other cases the stutter occurs on scenes that I wouldn't think should
> be problematic, such as static camera shots of talking heads against
> black backgrounds that should not be very complex at all.
> I have an AMD Athlon X2 3600 Brisbane core cpu coming for my seperate
> backend machine.  I'll have the opportunity to temporarily replace the
> Sempron 3400 in my frontend while maintaining the exact same software
> configuration so it will be interesting to see if there is any change
> but I'm not holding my breath.
> I've been doing a lot of research of the stuttering issue and there
> seems to be a lot of grumbling and suspicion of the OpenGL vertical sync
>   options but basically I still have no idea what is causing the problem.

I was just going to say, if your CPU is known to be fast enough (ie
others with the same CPU have no issue), check that your output
frequency is correct.

I also *highly* recommend using the 9xxx series drivers for HDTV,
enabling Vsync with the UseTextures=True xorg option. I noticed on my
already working system that doing this dropped my CPU use down while
clearing up any picture issues I was having before (slight tearing
near the top of the screen). The 9xxx series also has the nice
ModePool capabilities.

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