[MEncoder-users] Fwd: Questions on Mencoder performace

[Phil Ehrens]

larrystotler at netscape.net wrote:
> 
>  mencoder file -alang en -oac mp3lame -ovc xvid -xvidencopts 
> pass=1(pass=2:bitrate=1536) -o file
> 
>  On my Xeon system, I get 49% CPU usage, but I can start 2 encodings at 
> one time. I generally get about 10 frames first pass, 5 2nd pass.
>  On my P3-900, I get similar results. This mobile proc has 100Mhz 
> external bus
>  On my CeleronM 2.4Ghz, I get 13-15 frames first pass and then 13-15 
> frames second pass.
> 
> My questions are:
> 
>  How much does L2 cache impact performance? Is 512k L2 a huge benefit 
> over 256k? Would a real P4 be better than the Celeron Mobile?
>  How much does memory speed impact performance? Would switching the 
> CeleronM to DDR make a small or huge difference?
>  How much does Hard Drive speed affect performance? I have a SATA and 
> SCSI 10k/80M/s drives in my Xeon, and ATA100s in the other 2
> Are there further command line arguements that I need?


None of these things will give you as big a performance boost as
switching from xvid to lavc will. Using '-oac copy' will also give
you a performance (and quality) boost. Good starting options for
lavc:

-lavcopts vcodec=mpeg4:nr=1000:mbd=2:v4mv:trell:vpass=N:vbitrate=1800

You will want to look into the docs for using cropdetect as well.