[mythtv-users] HDTV question

Jason Schloer schloer.jason at tangoinc.com
Tue Oct 21 10:50:51 EDT 2003


On Mon, Oct 20, 2003 at 09:26:25AM -0400, Jason Schloer wrote:
> Okay so I've had the pcHDTV a couple weeks now and haven't had much
> chance to play with it. I did notice fairly quickly though that it
> wasn't playing things back quickly enough. So I went out and bought a
> different GeForce with IDCT acceleration so I could use that. Compiled
> myth for it tried it out, got the black and white overlays indicative
> that it was working, but it was still slow, if not slower than before.
> So I took it back and bought a faster processor, from XP 2000+ to XP
> 2600+. Tried it out again and again it was choppy audio and video. So
I
> think my bottleneck may be elsewhere. I need to do more testing, like
> checking CPU usage while watching to find out if it is pegged or has
> some room. I was wondering if anyone who's had some experience with HD
> streams could be of any help. Where should I check? I've got a 7200
RPM
> HD, 512 megs of ram, Asus A7N8X mobo. I'm running a vanilla Mandrake
9.1
> kernel. Also, will any of the hardware decoders help with this? Thanks
> for all your help can't wait to start really using this stuff. 
> 
> Jason Schloer
> P.S.
> The stream I was trying to watch is a 0 fps 480P stream with a 48000
hz
> AC3 audio track.
> 
> 

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-----Original Message-----
From: mythtv-users-bounces at mythtv.org
[mailto:mythtv-users-bounces at mythtv.org] On Behalf Of Brandon Beattie
Sent: Monday, October 20, 2003 11:43 AM
To: Discussion about mythtv
Subject: Re: [mythtv-users] HDTV question

I'm running a 2600+ (333fsb) AMD XP system (Via motherboard that is
junk).  Every once in a while I get choppy audio/video but this is due
to bugs, not lack of hardware resources.  Try running 'mplayer
/dev/video32' and see how that runs, or run xine.  If both of those are
still choppy, then check bios settings.  Sometimes running optimal
settings actually slows down a system as I have found out.  Also check
how much disk io you're using.  It shouldn't be a problem, but maybe
your drive is very slow?  (I run a 7200 ATA 100 drive, with my root
filesystem on another drive than where I store data to, but I've seen,
and also at one time, ran it off a single 7200 rpm drive).  Running that
mplayer command won't store to disk, just memory.  I still need to try
xvmc support in Myth.  I spent my few hours this weekend debugging
another pchdtv issue with the 2.4.20 debian kernel, (buffer
overrun/btatsc irq mask clearing) and upgrading to 2.4.22 fixed this
problem, but that's all I had time for, and to find out that
mythfrontend locks when changing a channel for myself).


I just noticed your specs, not sure how I missed them before, but you
should be fine.  I use about 87% CPU when watching a 1080i stream and
about 14% when watching a 480p stream.  Let me know how mplayer (Latest
version) and xine-hd work.

--Brandon


Okay, so I got home last night and took a look at it, turns out I still
had my XvMC enabled version of Myth installed. Noticed when I brought up
the pause menu. Recompiled without XvMC and it worked much better. Still
a little choppy but not maxing out CPU, so I turned on the experimental
AV sync and it works nice and smooth. Oh the other thing I realized is I
wasn't watching a 480p stream. Got confused because it had those nice
black bars on the sides, but it was actually a 60 fps 720p stream. So
I'm a little less worried now. I think a little more tweaking and it
should be all good. Anyway, thanks all for the help.

-Jason
PS
My drive seems to be okay btw. I sent the whole file to /dev/null in
under 3 minutes, for a 1 hour show. 




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