Additions are marked like this.

Memory is important. So go get phosphore. I just upgraded my machine from 64Meg to 96 Meg, and the (Mpeg2Dec) framerate jumped from 17 to 25 fps. Sure, my machine is slow (P2/233), and I'm really waiting for an accelerated mpeg driver for my Rage128 (see GatosProject), but if you have only 64 Meg, add some more memory... JeremyErwin  

  

== XVideo ==  

Run {{{xdpyinfo}}} and look for {{{XVideo}}} extension.  

  

Run {{{xvinfo}}} to see supported modes.  

  

== MTRR Setup ==  

  

For details on how to do this, check the LAMP FAQ located at http://pauillac.inria.fr/lamp/faq.html  

  

This could dramatically boost your mpeg decoding performance:  

  

Configure the MTRR registers (/proc/mtrr) so that your frame buffer is accessible in write-combining mode. If you have XFree 4.x, this is done automatically, but with XFree 3.x you have to do it yourself. Once your MTRR registers are properly configured you should see something like this :  

  

{{{  

# cat /proc/mtrr  

reg00: base=0x00000000 ( 0MB), size= 256MB: write-back, count=1  

reg01: base=0xe2000000 (3616MB), size= 32MB: write-combining, count=2  

reg07: base=0xe4000000 (3648MB), size= 64MB: write-combining, count=1  

}}}  

  

== DMA Disk Access ==  

  

If you use IDE disks, make sure they are accessed in DMA mode, not PIO. PIO is still the default, but it is a very large performance hit, because it does not let your system work on mpeg decoding and read from the disk in parallel. Make sure you run a command similar to hdparm -d1 /dev/hda. You will probably need additional arguments, and please read the man page first because you can break your filesystem if you abuse this command.  

  

== AUDIO Performance ==  

  

If you have certain audio cards (I have a ESS 1938 PCI card) using  

the ALSA drivers seems to help quite a bit. The kernel module for audio  

made listening to the soundtrack painfully full of pops and clicks.  

Loading the ALSA driver for reduced my audio noise to ZERO.  

  

ISA sound cards also can have impact on the performance, because ISA  

DMA seems to need some processing power. Upgrading to a cheap PCI sound  

card can give you a few fps and is cheaper than a new video card.  

See [http://www.alsa-project.org/~goemon/] for a list of ALSA-supported  

cards.  

  

== Find the Problem ==  

  

One way to determine if your processor is fast enough to decode video is to run Mpeg2Dec (or maybe OpenMediaSystem) with no video output. If the frame rate is ''much'' higher than with video enabled then your problem is the video driver or video hardware.  

  

Something like this: {{{mpeg2dec -o null foo.mpg}}}. Compare framerate with {{{mpeg2dec -o xvshm foo.mpg}}} (or whatever driver you want).  

  

Also see PerformanceResults.  

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