[mythtv-users] Epia-M10K (Nehemiah) software mpeg2 decoder performance

[Kenneth Aafløy]

On Wednesday 25 February 2004 03:53, Mikhail D'Vane wrote:
> Hello,
>
> I have set up an Epia-M10000 (Nehemiah) as a mythtv remote
> frontend.  Unfortunately, the system has a problem that I have
> been trying to debug for months (literally).
>
> My problem is that when using software mpeg2 decoding (encoded
> with a PVR-250 on my backend system), the CPU utilization for
> the frontend jumps to ~100%.  This results in very poor playback
> performance (crackly audio, periodic video pauses).

Normal (at least for MythTV)!

> Here's the odd thing, though - I know that the Nehemiah can
> handle mpeg2 software decoding at the resolution/bit rate I have
> set (480x480, 4500/6000max bitrate).  I know this because I have
> set up a system for a friend with the exact same motherboard type.
>
> Here's the quick background story....
>
> Orignally, I setup a mythtv system on a 1Ghz PentiumIII system
> that I had spare.   I used RH9.0 and followed Jarod's (extremely
> well-written) install guide using rpms maintained by Axel Thimm.
> My friend liked the system so much he asked me to build him one.
> However, he didn't have a spare system, so we bought all new
> components and I built a mythtv system (frontend/backend combined)
> around an Epia-10K for him.  This system was also using RH9.0,
> but I had to deviate significantly from Jarod (and Axel's)
> configuration because the Via binary drivers only worked against
> the stock RH9.0 kernel.
>
> Once I had my friend's system working, I liked it so much I decided
> to invest in an Epia-10k for myself.  I followed the same setup
> routine as before, but I ran into this performance problem.  Playing
> the same file, my system pegs at 100% cpu (used by mythfrontend)
> while my friend's hums along at about 50%.
>
> Here's the information on my (and my friend's) system:
>
> RH9.0 stock kernel (2.4.20-8)
> mythtv-0.12
> ALSA v0.9.8 (using OSS emulation)
> Software mpeg decoding (not using viaslice)
> Stock RH9.0 Xfree (4.3.0?)
> Via binaries 40037 (Xfree, kernel modules)
>
> I have tried the following to try to alleviate this problem:
>
> - enable "extra audio buffering" - still at 100% CPU, audio fine,
>   but everything pauses at 2 sec intervals (prebuffering pause)
> - try different versions of mythtv (tried 0.13 and 0.14)
> - upgrade Via binaries to 40038 package
> - run with Native ALSA
> - upgrade ALSA to later revision (1.0-pre3)
> - use open-source versions of Via binaries
> - Add "pci_retry=true" to the Devices section of my XF86Config file
> - Ensured that v4l and dri Xfree modules are loading (glxgears ~380fps)
> - Corrected the incorrect MTRR settings set by XFree for the Epia HW
> - Ensured that both systems are running same bios (1.0F) and have same
>   bios settings
> - Ensured that dxs_support=3 is set for the snd-via82xx in modules.conf
> - Ensured that my HDD is using DMA (hdparm -d /dev/hda says using
>   DMA is ON)
> - Changed Linux distribution from RH9.0 to Gentoo 1.4
>   (running 2.4.24-epia1 kernel)
> - Built everything (mythtv, ALSA, etc) from source (pretty easy
>   with Gentoo ebuilds)
> - Upgraded Xfree to Epia-centric version per Rroet's "Gentoo on Epia"
>   install guide
>
> None of the above made any difference in my playback performance.
>
> The only thing that makes my Epia system usable is to using the Epia's
> onboard MPEG decoder.  The playback is then smooth (mythfrontend using
> ~20%),
> but the system is not as stable as I would like.

Look above, and insted report as detailed reports about the real problems with 
your hardware (ie. cle266 decoding) as you have done for software decoding!!

> Also, there are some minor differences between my system and my
> friend's.  They are:
>
> - All his filesystems are ext2, mine are ext3 (boot) and reiserfs
>   (root and video partitions)

ext(2|3) seems to have good performance, but suffer when doing deletion of 
very large files (even worse when formatted wrong).

> - His system was setup with Axel's mythtv-0.12 distribution while mine
>   was (initially) setup with Axel's mythtv-0.13 distribution and
>   downgraded to 0.12
>
> Also, both systems have the same CPU utilization (~30%) when playing
> back DVDs with Xine.

And both with MythTV CLE266 Hardware Decoding?

> Does anyone have any additional pointers for me to try?  I saw a message
> from Isaac to Tako regarding Tako's high Nehemiah CPU utilization, but
> I never saw a post on a resolution.

Dunno..

> At this point, I'm considering cloning my friend's HDD to see if putting
> his exact software on my hardware resolves the issue.
>
> That... or using the onboard mpeg decoder and dealing with the lower
> stability.

Why is the onboard decoder so bad? I get less that 20% util, which would imply 
that i could do some simple postprocessing on the video also...

> Thanks for any help and also thanks for reading this (long-winded) email.

Your welcome, although i tend to write slow and short..

-- 

Kenneth
ke-aa at frisurf.no