[mythtv-users] Another performance question...

[Jeremy Hanmer]

I'm running the following system with no problems:

1.43ghz athlon-xp
512MB ram
7200rpm drive connected via firewire for all recordings (hdparm reports
28MB/s read speed)
basically the same capture card (WinTV-DBX)
Nvidia GeForce4MX with 64 megs

so it looks like you should have more than enough power.  My first guess
would be either motherboard (DMA issues, perhaps?) or buggy video
drivers since it's a relatively new card (or are you maybe just not
running the binary nvidia drivers?).

It may also be a matter of compilation flags, but with a 2ghz machine,
I'd expect smooth recording/playback even with very laid-back
optimizations.

To rule out a problem with Fedora (which I've heard there are plenty
of), you could try KnoppMyth.  It's just a bootable cdrom image with a
debian installation on it...should to the trick for testing.

http://hust.la/KnoppMyth/

On Fri, 2003-12-05 at 22:14, Mark Frey wrote:
> Not to add more noise on this sort of issue, but...I suppose I am
> going to add more noise ;)
>  
> I find myself unable to get live tv stutter-free on the following
> machine:
>  
> Intel P4 2.0GHz
> 512 MB ram
> 5400rpm HD (hdparm says throughput = 30MB/s, DMA is on)
> NVidia GeforceFX 5200 video card with open source drivers
> Latest Alsa with drivers for MAudio Delta66 soundcard
> bt878 capture card, using btaudio (quite new version of bttv, whatever
> installed with Fedora Core)
> Latest MythTV from CVS
>  
> If I try and run with the default live-TV settings (480x480, RTJpeg),
> I'll be fine for "talking-head" type shows (News, etc.), but sports
> programming (basketball for example) will cause more-or-less constant
> stuttering (quarter second lurches every 1 or 2 seconds). Processor
> usage stays near but below 50%.
>  
> I've read through all the posts I can find, and it seems like some
> people have no problem with performance with this spec machine, while
> others have trouble with even beefier machines. I'm trying to figure
> out what the magic is to make this work. I've instrumented the code to
> try and determine where my machine is falling down. So far, from what
> I can tell the decoder thread winds up spending alot of time waiting
> for the ring buffer read thread to fetch data. Whether this is because
> the hard drive is unable to keep up (the size on disk of each frame is
> bigger for sports programming because it doesn't compress as well), or
> because the read thread is getting starved because
> compression/decompression is taking alot of processor time I don't
> know. I'm kind of new to Linux so I don't know the best way to monitor
> hard drive use (any pointers?)
>  
> I've turned jitter reduction on and off, messed with the audio
> buffering settings, all to no avail.
>  
> My question is: Should this machine be able to do this? Are others
> able to get smooth playback with this sort of setup, specifically for
> sports programming?
>  
> Thanks for any tips anyone can offer.
>  
> -Mark
>  
> 
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