Hardware

Faster Hardware

Buy faster hardware!

Yes, throwing money at the problem will help.

Memory is important. 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

Use XVideo if possible. This is supported in XFree86 4.0.x or greater for some video cards. See HardwareCompatibility.

Run xdpyinfo and look for XVideo extension.

Run xvinfo to see supported modes.

MTRR Setup

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. Please someone include a description of how to do this. 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.

Software

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.

Compiling

Compile with optimizations such as -O3.
Don't compile with debug flags (--enable-devel) that spew lots of output to the console.

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