[FFmpeg-devel] [PATCH] SSE RDFT

[Ronald S. Bultje]

Hi,

On Thu, Jun 24, 2010 at 5:20 PM, Jason Garrett-Glaser
<darkshikari at gmail.com> wrote:
> 2010/6/24 M?ns Rullg?rd <mans at mansr.com>:
>> Michael Niedermayer <michaelni at gmx.at> writes:
>>> btw, speaking of yasm, a not too long while ago i realized that configure
>>> simply compiles without yasm optimizations if yasm isnt installed
>>> i noticed it just because x264 doesnt and warns, we should do the same
>>> this issue alone weighs heavier than any difference between inline and
>>> yasm. Because loosing the optimizations without the user knowing is really
>>> bad.
>>
>> Done.
>
> This is not sufficient. ?From years of experience with x264, people
> will NEVER NOTICE the configure warning, and will proceed to compile
> obliviously. ?They will then complain incessantly about slow it is.
>
> This is doubly important with more and more of ffmpeg's asm being in
> yasm -- particularly the upcoming VP8 decoder, where we are going to
> market ourselves on speed.
>
> I suggest that configure fail with an error (telling the user to
> install yasm or disable asm) if the following conditions are true:
>
> 1) architecture is x86 or x86_64
> 2) --disable-mmx is not set
> 3) --disable-yasm is not set

This is probably a good idea.

Note how libvpx has some script that translated from yasm to bla*asm,
similar to mru's iphone script, maybe we need something like that for
the future? (Wild idea, reject if not practical.)

Ronald