"10-bit newbie" encoder questions

[hydra3333]

Hello, a few "10-bit newbie" encoder questions and I'm hoping for some pointers.

Now I have a cheapie 4k hdr TV (a lightning strike nearby injured a neighbour and killed my previous TV), I would like to start experimenting with high bit depth encoding (10 bit ?) from the commandline however I have a few questions before I can start. I've googled but couldn't find easy answers from the tonnes of hits.

I have access to 64bit ffmpeg, x264.exe and x265.exe built with high bit depth enabled (per rdp's ffmpeg cross-compiler build suite) and an nvidia 750Ti (maxwell?) card which I suspect doesn't do 10 bit hardware encoding; next year I hope for a 1050Ti or similar and maybe a cheapie ryzen 1800x

I currently use this for standard h.264 encoding of PAL (generally mpeg2) sources

"C:\SOFTWARE\Vapoursynth-x64\VSPipe.exe" --y4m ".\z.vpy" - | "C:\x64_high_bitdepth\ffmpeg.exe" -threads 0 -i pipe: -threads 0 -an -threads 0 -map_metadata -1 -sws_flags lanczos+accurate_rnd+full_chroma_int+full_chroma_inp -filter:v setdar=dar=16/9 -c:v h264_nvenc -preset hq -bf 2 -g 50 -refs 3 -rc:v constqp -global_quality 18 -rc-lookahead 32 -profile:v high -level 4.1 -pixel_format yuv420p  -threads 0 -movflags +faststart -y ".\z-temp-h264.MP4"

So,

1. Can vspipe deliver high bit depths from vapoursynth scripts and if so, is that vspipe commandline correct ?
This http://www.vapoursynth.com/doc/gettingstarted.html#output-with-vspipe doesn't really say.

2. What ffmpeg settings would I use for high bit depth encoding in ffmpeg for h.264 (and h.265) ? This post https://ffmpeg.zeranoe.com/forum/viewtopic.php?t=3729#p10866 suggests that nvenc in ffmpeg can't do it "... there needs to be a few additions to unlock 10 bit encoding in NVENC HEVC. At the moment it's clear that ffmpeg only implements the Main profile of NVENC HEVC, and not the Main 10."
Maybe "-pix_fmt yuv420p10" ? ... except for this https://ffmpeg.zeranoe.com/forum/viewtopic.php?t=3729#p11035 "As of yesterday, my 10-bit NVENC encoding patches are in the official FFmpeg however they rejected the YUV420P10 part of it because it involved some conversion code which needs to be in a different place to where I put it and I don't have the time to do that at the moment. So if you plan to use later versions of FFmpeg in future then you will only be able to encode YUVP010 or YUV444P16 10-bit input formats".

If that's the case (no to ffmpeg with nvenc) then I suppose equivalent non-NVENC ffmpeg, x264 and x265 comnmandlines would be needed instead ... suggestions welcomed where to look to get me started with equivalents to my usual settings.

3. I am also tempted to experiment with NVEencC which seems as if it can accept .vpy vapoursynth scripts as native input (?) ... provided the 750Ti can do nvenc 10 bit hardware encoding.

Suggestions or a link to examples to start would be appreciated.

[sneaker]

1. Yes
vspipe --y4m "input.vpy" - | x265 - --y4m -D 10 -o "output.265"
("-D 10" is only needed for multi-bitdepth builds)

ffmpeg should be similar:
vspipe --y4m "input.vpy" - | ffmpeg -f yuv4mpegpipe -i - -c:v libx265 -crf 18 -preset medium -x265-params D=10 "output.265"
(I have not actually tested the "-x265-params D=10" part)

10 bit HEVC encoding was only introduced with Pascal so no luck with a 750 Ti.
https://en.wikipedia.org/wiki/Nvidia_NVENC#Fourth_Generation_.28Pascal_GP10x.29

[hydra3333]

Ah. Thank you !

Now to check for the h.264 equivalent.

edit: a very interesting discussion https://forum.doom9.org/showthread.php?t=174314&page=2