[FFmpeg-cvslog] r16207 - trunk/libavcodec/h264.c

[Michael Niedermayer]

On Thu, Dec 18, 2008 at 03:57:54AM +0000, M?ns Rullg?rd wrote:
> Michael Niedermayer <michaelni at gmx.at> writes:
> 
> > On Thu, Dec 18, 2008 at 02:57:17AM +0000, M?ns Rullg?rd wrote:
> >> michael <subversion at mplayerhq.hu> writes:
> >> 
> >> > Author: michael
> >> > Date: Thu Dec 18 03:53:18 2008
> >> > New Revision: 16207
> >> >
> >> > Log:
> >> > Use the new idct functions (except chroma as it was slower in benchmarks)
> >> > cathedral +0.5% speed
> >> > aladin +0.6% speed [note aladin has been cat-ed 10 times to reduce the influence
> >> > of init time]
> >> > Speedup also verified via START/STOP_TIMER (difference was very significant
> >> > for the changed parts)
> >> 
> >> How much does this hurt on architectures that don't yet have the new
> >> SIMD functions?
> >
> > there are no really new SIMD functions.
> > I just moved the loops like
> > for(i=0; i<16; i++)
> >     dsp->idct4x4_add(blah blah);
> >
> > into dsputil so they are
> >
> > for(i=0; i<16; i++)
> >     idct4x4_add_simdwhatever(blah blah);
> >
> > that way gcc can inline the function and avoids up to 15 calls through dsp->
> >
> > adding support for this to your favorite architecture is a matter of copy
> > & paste and adjusting the function names.
> 
> I can see how it can be done.  I'm asking how much of an impact this
> has on performance until it's been done.  What percentage of the old
> calls are affected?

depends on the video, if i have to guess and thats just a guess id say
more than 50% of the idct work will go to new code


[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Breaking DRM is a little like attempting to break through a door even
though the window is wide open and the only thing in the house is a bunch
of things you dont want and which you would get tomorrow for free anyway
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