[FFmpeg-devel] swscale : add bitexact conv for grayf32 and gray16 to f32 conv

[Martin Vignali]

>
> also there are 2 divisions in this that you can trivially eliminate
> /255 and /65535 (extra precission beyond IEEE float/double could change
> these)
>
> also the whole could be done with fewer floats and no extra complexity
> for example:
> int64_t tmp2 = 16843009LL * i;
> (float)((double)tmp2 / (1LL<<32))
> and
> int64_t tmp2 = 4295032833LL * i or uint64_t 281479271743489
>
>
Still raise the assert for me.
Maybe we can go back to the initial patch i propose.
Let the simple initial code, for non bitexact conversion
and use a dedicated calc for bit exact version, without float calc

Martin