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Old 3rd September 2021, 07:22   #1  |  Link
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Chroma subsampling : 4:2:0 (Type 1 / Type 0)

I've been experimenting with DVDFab for Blu-ray to x265 (I'm happy with a CLI but find tools with GUIs fun to play around with, like Staxrip - never Handbrake as it's horrible) conversion and found - annoyingly, after converting about a dozen films - an oddity with the output.

For some reason, the blacks are washed out and I believe it's down to the chroma subsampling it's using.

Partial mediainfo output (I know it's 8-bit which I wouldn't normally choose for HEVC).

ID : 1
Format : HEVC
Format/Info : High Efficiency Video Coding
Format profile : Main@L4@Main
Color space : YUV
Chroma subsampling : 4:2:0 (Type 1 / Type 0)
Bit depth : 8 bits
Color range : Full
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709
I believe the part marked in bold is the cause of the problem. I've never encountered an issue with 4:2:0 Type 1/0 so not entirely sure what's going on. Is this something that can be fixed without encoding the Blu-rays again (e.g. a flag in mkvmerge)? As I don't seem to have this issue with x264, is it related to that in some form?

Here's a simple demonstration of the issue - the grey area should be black.

Direct link to png: https://i.ibb.co/CHfwnwZ/dvdfab-outp...roma-issue.png

Any thoughts on the matter are much appreciated.
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chroma subsampling, x265

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