[FFmpeg-devel] [PATCH] Fix function parameters for rgb48 to YV12 functions.

[Michael Niedermayer]

On Tue, Feb 02, 2010 at 04:10:06PM -0200, Ramiro Polla wrote:
> Hello Michael,
> 
> On Sun, Jan 24, 2010 at 8:31 AM, Michael Niedermayer <michaelni at gmx.at> wrote:
> > the gain happens when you change the variables used to calculate the index
> > also to it. You could also try to make the index unsigned but make sure it
> > cant be negative if you try this
> 
> Sorry but I still don't understand how that will be of use here in
> libswscale. I've tried forcing int32_t and int64_t for x86_64 in some
> of those functions (some xxxTo(Y|UV), hScale and the fast bilinear
> ones), in all C, MMX and MMX2. All I can see is the expansion from
> 32-bit to 64-bit being changed from caller and callee. There is no
> difference in the inner loop, nor in how gcc addresses the the src and
> dst arrays.

maybe theres no gain for swscale, i cant say without looking at the asm
gcc generates.
i know that in h264 gcc filled some functions with 32->64 sign extension
code in the inner loops.

if there are no sign extension instructions betweem registers in the inner
loop then theres no problem you could fix with this

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

He who knows, does not speak. He who speaks, does not know. -- Lao Tsu
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: Digital signature
URL: <http://lists.mplayerhq.hu/pipermail/ffmpeg-devel/attachments/20100202/3af59f26/attachment.pgp>