[MEncoder-users] Fwd: Questions on Mencoder performace

[Phil Ehrens]

Raphael wrote:
> larrystotler at netscape.net wrote:
> >-----Original Message-----
> >From: Corey Hickey <bugfood-ml at fatooh.org>
> >
> >>I don't know specifically about your systems, but I wouldn't expect 
> >much performance out of a P4. I did some rough tests with lavc and 
> >x264 a while back and found >that a 1.2 GHz Athlon Thunderbird was 
> >outperforming a 1.7 GHz P4 by 10-20%. As far as I know early Athlon 
> >processors were roughly equivalent to late P3s, >clock-for-clock, so 
> >the numbers you posted don't seem out of line.
> >
> >Hmmm, I was under the impression that the P4 was actually optimized 
> >for stuff like this and that it should outperform the Athlon in this 
> >regard.  I've never been a fan of the P4 series, but I ended up with 
> >with some chips and was hoping that they would be well suited for this 
> >type of stuff.  Oh well.  Thanx for the insight.
> >
> >I appreciate all the advice that has been given to me by the list 
> >members.  Thanx.
> >___________________________________________________
> 
> 
> Whenever anybody starts being rude on this list it's because they don't 
> know the answer. So don't worry about that :) 
> 
> Your best bet is to experiment.  There are too many unknowns and in 
> particular of course the behaviour of the compiler will make a 
> considerable difference.  One version of gcc with one set of 
> optimisation flags may accidently squeeze some crucial piece of data 
> into the L2 cache on a particular processor etc.   gcc has never given 
> any guarantees and I remember compiling code with higher optimisation 
> levels that ran more slowly and finding that after using -Os it didn't 
> fit in cache etc.
> 
> You may be able to find tools that give you useful stats (e.g. 
> cachegrind http://valgrind.org/info/tools.html). If you can run 
> systematic tests using such tools with as many different gccs and 
> options and cpus as possible then I am sure we would all be very 
> interested to see the results.

As warm and fuzzy as that may sound, since mencoder does not have
a uniquely defined data path there is nothing to test. Would you
have him benchmark '... -oac copy -ovc copy ...' or '... -oac mp3lame
-ovc lavc -vf ??? ...'?