Help with banding issues from denoising

[Soloiam68]

Just a noob question. How can I prevent banding that appears after denoising? I used a 16-bit source for denoising, but some banding still appears in gradients. There are debanding filters available, but using those on a full video seems unnecessary. Are there any denoisers that can prevent this, or any specific x265 settings that might help?

[Selur]

If the banding is not present when previewing your script, make sure to use 10bit x265 and not 8bit encoding, also try increasing the bitrate.
If the banding is present when previewing your script you would need to add some debanding. (If you don't want to apply it to the whole video, apply it only to the sections you want to.)

[Soloiam68]

If the banding is not present when previewing your script, make sure to use 10bit x265 and not 8bit encoding, also try increasing the bitrate.
If the banding is present when previewing your script you would need to add some debanding. (If you don't want to apply it to the whole video, apply it only to the sections you want to.)
@Selur, a little banding is present in the preview, and after encoding, it becomes worse. When I used DitherPost from the package DitherTools with stacked LSB output from MDegrain3, the banding is nicely resolved in the preview. However, if I use single plain 16-bit input directly fed into MDegrain3, it causes some banding. Is DitherTools applying some debanding filter in addition to dithering? DitherTools only outputs 8 bits. Is there a similar filter for 10-bit? Finding banding throughout an entire movie manually is very hard and time-consuming :(

[Selur]

Sorry, no clue, I usually don't use DitherTools but http://www.avisynth.nl/index.php/F3kdb for debanding.

[hello_hello]

You could try GradFun3 instead of DitherPost. The output is 8 bit but you can still encode as 10 bit. It'll fix minor banding and help prevent the encoder from causing it.

There's also Dogway's GradFun3Plus version.
https://github.com/Dogway/Avisynth-Scripts/blob/master/EX%20mods/GradFun3plus.avsi

ConvertBits(16)
GradFun3Plus()
ConvertBits(10, Dither=0) # or Dither=1 if you prefer.

I hardly ever encode without GradFun3 or GradFun3Plus at the end of a script as it is too time consuming to manually find banding.

[tormento]

Give a try to libplacebo_Deband (https://github.com/Asd-g/avslibplacebo), it works in 8 or 16 bits.