[FFmpeg-user] RGB-YUV color shift

Vincent Olivier vincent at up4.com
Mon Apr 29 21:58:56 CEST 2013

On 2013-04-29, at 11:03 AM, chris bouchard <chris.bouchard at framestore.com> wrote:
> I was using an RGB image sequence source - not a quicktime source, 
> so that might already be 
> assumed to be 709...
> In the end I found that the default scaler was causing the slight green tint.
> If you add this flag:
> -sws_flags lanczos+accurate_rnd   
> this fixed the green tint I was experiencing with the default down scaling. 
> Note that lanczos alone will go green without the +accurate_rnd option.

Sweet baby jesus!!! That's exactly what I'm looking for (I think). Does it mean, in the case of a 422 to 444 rescaling, that the "accurate lanczos" only "adds" the interpolated lines to the chroma channels and leaves the luma channel and the original chroma samples as-is? 

Because if it does, that's what I was trying to make sure, and if it doesn't, well, the quest goes on! And also, what DOES it mean? :D


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