[FFmpeg-devel] [PATCH] Use av_clip_uint8 in swscale.

[Reimar Döffinger]

On Sat, Aug 15, 2009 at 12:27:49PM -0300, Ramiro Polla wrote:
> diff --git a/swscale.c b/swscale.c
> index c513066..340acfc 100644
> --- a/swscale.c
> +++ b/swscale.c
> @@ -688,21 +688,12 @@ static inline void yuv2nv12XinC(const int16_t *lumFilter, const int16_t **lumSrc
>  
>  #define YSCALE_YUV_2_PACKEDX_C(type,alpha) \
>          YSCALE_YUV_2_PACKEDX_NOCLIP_C(type,alpha)\
> -        if ((Y1|Y2|U|V)&256)\
> -        {\
> -            if (Y1>255)   Y1=255; \
> -            else if (Y1<0)Y1=0;   \
> -            if (Y2>255)   Y2=255; \
> -            else if (Y2<0)Y2=0;   \
> -            if (U>255)    U=255;  \
> -            else if (U<0) U=0;    \
> -            if (V>255)    V=255;  \
> -            else if (V<0) V=0;    \
> -        }\
> -        if (alpha && ((A1|A2)&256)){\
> -            A1=av_clip_uint8(A1);\
> -            A2=av_clip_uint8(A2);\
> -        }
> +        Y1 = av_clip_uint8(Y1); \
> +        Y2 = av_clip_uint8(Y2); \
> +        U  = av_clip_uint8(U ); \
> +        V  = av_clip_uint8(V ); \
> +        A1 = av_clip_uint8(A1); \
> +        A2 = av_clip_uint8(A2); \

This

> -            if ((u|v)&256){
> -                if (u<0)        u=0;
> -                else if (u>255) u=255;
> -                if (v<0)        v=0;
> -                else if (v>255) v=255;
> -            }
> -
> -            uDest[i]= u;
> -            vDest[i]= v;
> +            uDest[i]= av_clip_uint8((chrSrc[i       ]+64)>>7);
> +            vDest[i]= av_clip_uint8((chrSrc[i + VOFW]+64)>>7);

And this need to be benchmarked (well, or at least have a look at the
generated code.
If clipping is very, very rare the original code might be faster.