[FFmpeg-devel] libavfilter-soc: negate filter artifacts

[Vitor Sessak]

Stefano Sabatini wrote:
> Hi,
> 
> I wonder what's the point of the default offesets assigned in the config_props:
> static int config_props(AVFilterLink *link)
> {
>     NegContext *neg = link->dst->priv;
> 
>     avcodec_get_chroma_sub_sample(link->format, &neg->hsub, &neg->vsub);
> 
>     switch(link->format) {
>     case PIX_FMT_YUVJ444P:
>     case PIX_FMT_YUVJ422P:
>     case PIX_FMT_YUVJ420P:
>     case PIX_FMT_YUVJ440P:
>         neg->offY  =
>         neg->offUV = 0;
>         break;
>     default:
>         neg->offY  = -4;
>         neg->offUV = 1;
>     }
> 
>     return 0;
> }

I think the problem here is that YUV (and not YUVJ) has Y data in the 
16...235 range. So ideally one would negate 235 <-> 16 (see 
imgconvert.c:47). But as you show in your message, the code is buggy.

-Vitor