[FFmpeg-devel] [augustus at linuxhardware.org: SSE4 and FFMPEG]

Zuxy Meng zuxy.meng
Tue Oct 30 12:18:11 CET 2007


2007/10/30, Loren Merritt <lorenm at u.washington.edu>:
> On 29 Oct 2007, Kris Kersey (Augustus) wrote:
> > I am writing an article about the new "Penryn" Intel processor for
> > LinuxHardware.org.  Can you or another member of the FFMEG team comment on
> > what impact SSE4 will have on FFMPEG and whether there are any plans to
> > write SSE4 optimized code?  Thank you for your time.
> I plan to write SSE4 code when I get an SSE4 capable cpu. Which is not
> immediately.
> Don't expect any drastic improvements. Every SSE4 instruction can be
> emulated with just a few SSE2 instructions, so it will only shave a few
> cycles of certain operations.

Unless it's inside a very short inner loop :-)

To be serious, only one instruction MPSADBW looks like something
gorgeous that may boost motion compensation, most others like what
Loren has said are simple combinations of two or three existing
instructions to help feed the execution engine faster.

> Furthermore, FFmpeg contains many functions
> that don't even have SSE2 versions. MMX2->SSE2 should make more difference
> than SSE2->SSE4.

What about the 8 additional XMM registers under AMD64?
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