[Ffmpeg-devel] a little optim for a SSE version of H263_LOOP_FILTER

[Kostya]

On Sat, Nov 11, 2006 at 10:48:19AM +0100, Stefan Gehrer wrote:
> skal wrote:
> >   btw, while i have the mike:
> >
> >   seems to me the following replacement functions for 
> >   vc1_v_overlap_c() and vc1_h_overlap_c() in vc1dsp.c:31
> >   are likely to be faster (and bitwise equivalent of course)
> >
> >static void vc1_v_overlap_c(uint8_t* src, int stride, int rnd)
> >{
> >    
> I am still surprised about the input to overlap being uint8_t
> as my understanding of VC1 was that the overlap has to be
> done with the pixels before clipping, which can be both
> negative and beyond 255. I remember someone brought this
> up before on the list but I think there was no response?

The logic is simple: while VC1 standard demands processing of
at least 10-bit samples lavc implies 8-bit samples. Any workaround
will be too messy and slow (and I don't think quality will
significantly degrade).

I think supporting 16 bit per sample formats (grayscale is already
supported) is nice but here it would be an overkill.

> 
> Regards
> Stefan Gehrer
>