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

[Daniel G. Taylor]

On Thu, Jan 12, 2012 at 00:09, Michael Niedermayer <michaelni at gmx.at> wrote:
> 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

I'm not entirely sure I understand the problem or the patch, but feel
free to apply whichever you like, Michael. I don't have much time
these days to fix up the deshake filter, though I would like to some
time.

Take care,
-- 
Daniel G. Taylor
http://programmer-art.org/