On 29.08.2014 12:31, Andy Furniss wrote: >> As for that 4:2:2 "doesn't work", AFAICT it absolutely does, but >> there is no linear interpolation for chroma, so quality isn't ideal. >> This seems to be a hardware restriction, unfortunately. > > Hmm, we may have to disagree on the definition of working here :-) > > Of course I don't understand the hardware - but are you saying that > because the chrome needs horizontal interpolation you have to have > vertical interpolation too? >
No, I just observed that there is no linear interpolation horizontally. I.e. the exact same chroma value is used for two pixels of the same block. > > Tests were 1:1 vertical scale. > > With weave shader a test pattern rgbymc 422 chroma looked much like it > would if I had used ffmpeg to convert to it 420 (ie none of those at all > rendered). On real video it bled between fields, so my use case of > feeding it to a TV to deinterlace would fail - luma was OK. > Hmm - where can I find this test pattern? I just made a simple test pattern myself: http://i.imgur.com/hsLFBxy.png I displayed it in mpv with the following command line: > mpv --vo=vdpau --vf=format=uyvy422 422-chroma.png I clearly see separate chroma for each line, but chroma cositing seems to be a bit off, i.e. chroma is shifted downwards by about half a pixel. That doesn't happen with forced progressive mode. So this is most probably it. Grigori
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