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

[Reimar Döffinger]

On Sat, Jan 07, 2012 at 09:51:23PM -0800, Ray Simard wrote:
> 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.

Well, I had hoped you could test my patch.
Yours needs more code changes and also leaves those pointless
int<->double conversions in (for example when comparing against rx/ry
limits).
Do we have a maintainer for that file? That would be the best person to
decide.