2nd pass won't start..."file size too small"

[Selur]

The command you gave in the above post runs fine, but I don't see an output file anywhere

It should not create an output file. The call just tests the decoding.

If the decoding doesn't throw any error. I seems like the problem lies with x265.

Do you get any more details when using a higher log level in x265? (using --log-level 4 instead of --log-level 2)

C:\PROGRA~1\Hybrid\64bit\ffmpeg.exe" -y -noautorotate -nostdin -threads 8 -i "D:\convert\result.mp4" -map 0:0 -an -sn -vf  scale=out_range=pc -pix_fmt yuv420p10le -strict -1 -vsync 0  -f yuv4mpegpipe - | "C:\PROGRA~1\Hybrid\64bit\x265.exe" --preset slow --log-level 4 --input - --output-depth 10 --y4m --profile main10 --ctu 32 --no-hme --merange 26 --no-rect --max-merge 2 --tskip --no-open-gop --opt-ref-list-length-pps --bframes 5 --rc-lookahead 40 --pass 2 --bitrate 4000 --opt-qp-pps --cbqpoffs -2 --crqpoffs -2 --fast-intra --psy-rd 2.20 --psy-rdoq 1.20 --splitrd-skip --deblock=-2:-2 --selective-sao 2 --limit-sao --no-repeat-headers --range limited --colormatrix bt709 --stats "D:\convert\result_new_17_23_01_7710_01.stats" --no-dynamic-refine --refine-ctu-distortion 0 --output "D:\convert\17_23_01_7710_03.265"

Also check your RAM usage.