[FFmpeg-devel] [PATCH] (New patch) Missing emms_c() calls causing weird Windows crashes with deshake

[Ray Simard]

On 01/07/2012 03:07 AM, Reimar Döffinger wrote:

> Doing emms_c in the inner loop will (at least on some processors) be
> far, far slower than not using MMX at all.
> An obvious approach is to do the conversion to double only after the
> emms_c.
> Of course I couldn't really figure out why the motion values are float
> anyway, it seems to me that they only ever get assigned ints anyway
> (and none of the video codecs use floating point for motion vectors,
> so IMHO the filter must be doing something wrong if it needs doubles)...

True, and there's no reason why it should be necessary to assign the int
values of x and y to mv inside the loops at all, even if the ultimate
values coming out of the process for some reason should be doubles.
Using a couple of simple int variables in the loops and assigning them
to the motion vector afterward does exactly the same thing, but with
less overhead and, of course, dodging the need for the emms_c() call.

This patch does that.  	I've tried it on a variety of files and as far
as I can tell, it's working properly.  I ran FATE on it manually and
there were no problems. I'm not sure what other testing is needed at my
end, so please advise me.

Regards,
Ray Simard
rhs.ffmpeg at sylvan-glade.com


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