[FFmpeg-devel] [PATCH 6/7] utvideoenc: align mangled buffer starts.

[Michael Niedermayer]

On Wed, Aug 22, 2012 at 11:12:11AM -0400, Derek Buitenhuis wrote:
> On 22/08/2012 10:26 AM, Michael Niedermayer wrote:
> > This is essential for fast SIMD accesses.
> > The same should be done with the predict output.
> > 
> > Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
> > ---
> >  libavcodec/utvideo.h    |    1 +
> >  libavcodec/utvideoenc.c |   14 ++++++++------
> >  2 files changed, 9 insertions(+), 6 deletions(-)
> 
> Is this a preemptive measure for future SIMD, or does it have direct
> benefits in this patchset? Just curious, as I'm a n00b at SIMD.

unaligned accesses with SIMD are slower and could even crash in some
cases


[...]
> > -            ret = encode_plane(avctx, c->slice_buffer[i] + width,
> > -                               c->slice_buffer[i], width,
> > +            ret = encode_plane(avctx, c->slice_buffer[i] + 2*c->slice_stride,
> > +                               c->slice_buffer[i], c->slice_stride,
> >                                 width, height, &pb);
> 
> 2*c->slice_stride -> 2 * c->slice_stride.

all fixed and applied

thanks

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

I have never wished to cater to the crowd; for what I know they do not
approve, and what they approve I do not know. -- Epicurus
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