[FFmpeg-devel] [PATCH] Optimized unscaled yuvp9/yuvp10 -> yuvp16 conversion.

[Reimar Döffinger]

On Sun, Aug 12, 2012 at 02:49:45PM +0200, Michael Niedermayer wrote:
> On Sun, Aug 12, 2012 at 02:47:09PM +0200, Reimar Döffinger wrote:
> > On Sat, Aug 11, 2012 at 04:52:19PM +0200, Michael Niedermayer wrote:
> > > On Sat, Aug 11, 2012 at 02:18:36PM +0200, Reimar Döffinger wrote:
> > > > About 30% faster on 32 bit Atom, 120% faster on 64 bit Phenom2.
> > > > This is interesting because supporting P16 is easier in e.g.
> > > > OpenGL (can misuse support for any 2-component 8 bit format),
> > > > whereas supporting p9/p10 without conversion needs a texture
> > > > format with at least 14 bits actual precision.
> > > > 
> > > > Signed-off-by: Reimar Döffinger <Reimar.Doeffinger at gmx.de>
> > > > ---
> > > >  libswscale/swscale_unscaled.c |   26 ++++++++++++++++++++++++++
> > > >  1 file changed, 26 insertions(+)
> > > > 
> > > > diff --git a/libswscale/swscale_unscaled.c b/libswscale/swscale_unscaled.c
> > > > index c391a07..6618966 100644
> > > > --- a/libswscale/swscale_unscaled.c
> > > > +++ b/libswscale/swscale_unscaled.c
> > > > @@ -830,7 +830,33 @@ static int planarCopyWrapper(SwsContext *c, const uint8_t *src[],
> > > >                          srcPtr  += srcStride[plane];
> > > >                      }
> > > >                  } else if (src_depth <= dst_depth) {
> > > > +                    int orig_length = length;
> > > >                      for (i = 0; i < height; i++) {
> > > > +                        if(isBE(c->srcFormat) == HAVE_BIGENDIAN &&
> > > > +                           isBE(c->dstFormat) == HAVE_BIGENDIAN) {
> > > > +                             unsigned shift = dst_depth - src_depth;
> > > > +                             length = orig_length;
> > > > +#if HAVE_FAST_64BIT
> > > > +#define FAST_COPY_UP(shift) \
> > > > +    for (j = 0; j < length - 3; j += 4) { \
> > > > +        uint64_t v = AV_RN64A(srcPtr2 + j); \
> > > > +        AV_WN64A(dstPtr2 + j, v << shift); \
> > > > +    } \
> > > > +    length &= 3;
> > > > +#else
> > > > +#define FAST_COPY_UP(shift) \
> > > > +    for (j = 0; j < length - 1; j += 2) { \
> > > > +        uint32_t v = AV_RN32A(srcPtr2 + j); \
> > > > +        AV_WN32A(dstPtr2 + j, v << shift); \
> > > > +    } \
> > > > +    length &= 1;
> > > > +#endif
> > > 
> > > these look wrong for the shiftonly==0 case
> > 
> > Ops, sorry, I went back and forth a few time how to handle that case
> > and at some point the condition was lost.
> > The code is not meant to handle shiftonly==0 because
> > a) The case I was looking at (MPlayer) never uses it
> > b) It needs an extra "and" compared to the non-SIMDified version,
> > which means for 32 bit it tends to not be relevantly faster, at
> > least for some compiler/compiler options variations (for example
> > when compiling with 4.6 for Atom the loop won't be unrolled, so
> > lots of loop overhead, whereas when compiling for k8 it will be
> > unrolled and prefetch added...).
> 
> ok then the patch LGTM with a if(shiftonly) added

Pushed the second version with that fix.