Quote:
Originally Posted by poisondeathray
So if you export some 4:2:2 format, you can downsample back to 4:2:0 using chromaresample="point" and it will look close to what you started with
#exported 4:2:2 format like prores
ConvertBits(8)
ConvertToYV12(chromaresample="point")
Or you can use avsresize eg. for 10bit , but 4:2:0
z_ConvertFormat(pixel_type="YUV420P10", resample_filter="point")
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So I decided to measure the PNSR of this. The numbers aren't stellar. I can't speak to whether the results are visually apparent or not. I didn't attempt to examine that aspect.
This is lossless:
Convert YV12 source to v210 in Avisynth -> uncompressed v210 .mov (VD2) -> Resolve -> uncompressed v210 .mov -> Avisynth convert back to YV12
This is not even close:
Compress the YV12 source to near lossless (qp 1 / keyint 1) H264 -> Resolve -> v210 .mov -> Avisynth convert back to YV12
The near lossless H264 compression is good for -~70-75dB
The Resolve -> YV12 in Avisynth step degrades it quite a bit further dipping all the way down to ~46dB for a section on my 5000 frame test clip.
My guess is that it has something to do with the chroma placement and the transformation matrix not aligning between the 4:2:0 -> 4:2:2 conversion in Resolve and 4:2:2 -> 4:2:0 back in Avisynth.
Edit: It seems like this is potentially a significant issue for anyone who uses 4:2:0 video from their cameras directly in Resolve and then exports from Resolve in a lossless or with a "light touch" codec to encode in something else. You can visually improve the chroma with a point resample of it back to 4:2:0, but you can't actually reverse the operation.
Also for a point of reference while I was at it I measured Cineform's performance (forcing a re-encode in Resolve) using the same flow vs. v210 uncompressed and got this:
Convert YV12 source to v210 in Avisynth -> CineForm FS3 v210 .mov (VD2) -> Resolve -> CineForm Best v210 .mov -> Avisynth convert back to YV12