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Export single frame darkened (Bug?)

Started by guju, November 12, 2023, 01:49:13 PM

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Take an mp4/h264/YUV420 movie

Open with MPC-HC or VirtualDub2
Export 1st frame (PNG)
Open movie with ADM.
Export 1st frame.
ADM frame is significantly (Not randomly, but overall) darker.

When recoding the movie with same settings (h264/YUV420/crf18)
the difference seems to be the same/ maybe stronger.

This is kind of importance as doing a detailed comparison
I often use frame export.


There are multiple pixel format and color range conversions involved, at least mpv screenshot seems to agree with JPEG export from Avidemux here (on macOS), but yes, it is generally a mess.


Thank you  :) - after all I do know now what's going on.



This might be an issue for you, as in my tests ADM generates the same (wrong) colors as ffmpeg.
In short: unsufficient flags for swscale.

Maybe not use swscale at all but zscale?