How to Choose between 8 and 10 bit colour depth?

[Gentlemen95]

I'm new to using this but basically i have finished doing an AI Upscale and cannot find any option to select 10 bit, i can see that i can select in Output Bit Depth only 8 bit, wheres 10 bit and why is it not there?

[eumagga0x2a]

As the internal pixel format in Avidemux is YV12 (planar 8-bit format with 4:2:0 chroma subsampling), asking for high bit output from video encoders provides little benefit (e.g. less banding) at cost of generating output which is often incompatible with hardware-accelerated decoders (i.e. unusable on mobile devices).

For 10-bit H.264, select "high10" profile in the configuration of the x264 encoder plugin. For HEVC, "main10" profile in the configuration of the x265 encoder plugin should enable 10-bit output (not sure that it really works there). In any case, I don't think that it makes much sense.

[radorn]

I actually started using main10 profile for x265 HEVC even though avidemux is capped at 4:2:0.
Obviously you don't magically regenerate the "original" 10bit at the source level, but it does give the encoder a little bit more depth to work with and I've noticed some improvement in my encodes with that. I think it even compresses a little bit better.
I saw this recommendation somewhere months ago, tried it, and was pleased with the results so it's my dafult setting now.

Of course, you need to make sure your target player can decode 10bit files.

[radorn]

Wait a minute... I've just realized that it has been removed!
main10 has been removed from x265! Why?

It may seem like there's no point to it for 8bit input, but I did some testing and it indeed gave me some improvement!
And now I just realize it's not there anymore...

EDIT: I made some x265 custom configs, and I did make them "main10 / 10-bit", and forgot about it.
But, now that it was mentioned, I went and checked, and realized it's not there anymore. When was it removed anyway?
How long have I been making new encodes with my custom configurations without realizing one of my options has disappeared.

I've gone a few nightlies back and still haven't seen the option again. This is confusing...

EDIT2: It's only absent in the Visual Studio compile?

[eumagga0x2a]

EDIT2: It's only absent in the Visual Studio compile?

That is easily possible, all depends on how the x265 library was built in the respective build environment.