[Mplayer-cvslog] CVS: main/mp3lib decode_MMX.c,1.8,1.9

[D Richard Felker III]

On Mon, Oct 27, 2003 at 10:44:56AM +0100, Arpi wrote:
> Hi,
> 
> > > > > > reverting my last change as buggy gcc 3.x fails with it :(
> > > > >
> > > > > gcc addresses local variables by ebp or esp, and push/pop change esp
> > > > > so it cant work (the correct solution would be to make some free space
> > > > > manually on the stack and use that instead)
> > > >
> > > > Strange is that it worked on 2.95.x
> > > >
> > > > Actually the whole code could be rewritten..it's crappy
> > >
> > > Actually optims should be ported/redone for ffmp3 and finally rm -rf mp3lib
> > > its just broken in many ways, not worth to fix.
> > I'm no mp3lib fan either, but keep in mind that it is still a lot faster on 
> > older systems (eg. Pentium II. tested that recently).
> 
> It's still a lot faster on any x86 systems, maybe on others too.
> I was trying to find bottlenecks of ffmp3, and optimize it but failed.
> The 3 most critical functions of ffmp3:
>   compute_antialias
>   compute_imdct
>   synth_fv
> 
> they are slow for 2 reasons:
> - no SIMD optims at all
> - uses integer (fixedpoint) only, which seems to be slower on intel x86 than float

Reason 2 is nonsense. On slower x86 (Pentium, K6, ...), integer is
MUCH MUCH faster than float! And slower systems are the only ones
where mp3 decoding time matters...

Rich