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

Michael Niedermayer michaelni at gmx.at
Thu Jan 12 06:09:16 CET 2012

On Sun, Jan 08, 2012 at 12:28:31PM +0100, Reimar Döffinger wrote:
> 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.

iam not sure if daniel has time, but adding him to the CC

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

You can kill me, but you cannot change the truth.
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