x265 encoding error.

[Selur]

Wouldn't it be better and more appropriate for the ffmpeg command to be -colorspace bt2020nc/bt2020_ncl instead of -colorspace bt709?

Yes, if you upscale, it would be better to also use a color matrix conversion to bt2020.

And now Hybrid generates the encodes correctly as Matrix coefficients BT.2020 non-constant, even though Hybrid has assumed the color as bt709 (since the video size is larger than 720*57).
Previously this did not happen and in that situation Hybrid generated encodes with Matrix coefficients BT.709.

If no color matrix is given, Hybrid uses:

if (m_currentWidth[variable] > 1920 || m_currentHeight[variable] > 1080) {
    if (VsFilter::m_videoFormat == QString("ULH0")) {
      sendMessage(HDEBUGSYNTH, QString("Unknown color matrix '%1' -> using '709', since input format is UHLH0").arg(inMatrix));
      return QString("709");
    }
    return QString("2020ncl");
  }

  if (m_currentWidth[variable] > 720 || m_currentHeight[variable] > 576) {
    sendMessage(HDEBUGSYNTH, QString("Unknown color matrix '%1' -> using '709'").arg(inMatrix));
    return QString("709");
  }

  sendMessage(HDEBUGSYNTH, QString("Unknown color matrix '%1' -> using '470bg'").arg(inMatrix));
  return QString("470bg");

to guess an input color matrix, which in my eyes seems correct.

------------
About the crash, the debug out complains about:

Error initializing the muxer for 3840:2064:0:48,scale=1920:1032: Invalid argument
Error opening output files: Invalid argument

for:

"C:\Program Files\Hybrid\64bit\ffmpeg.exe" -y -loglevel fatal -noautorotate -nostdin -threads 8 -i "C:\Users\cebol\Desktop\ENCODES\MapNLQ.avs" -an -sn -vf format=yuv420p10le,crop= 3840:2064:0:48,scale=1920:1032 -color_primaries bt709 -color_trc bt709 -colorspace bt709 -color_range tv -pix_fmt yuv420p10le -strict -1 -vsync 0 -sws_flags spline -f yuv4mpegpipe - | "C:\Program Files\Hybrid\64bit\x265.exe" --input - --fps 24000/1001 --output-depth 10 --y4m --profile main10 --level-idc 5.1 --qg-size 16 --tu-intra-depth 4 --tu-inter-depth 4 --limit-tu 4 --me star --subme 7 --limit-modes --max-merge 4 --no-early-skip --rskip 0 --no-open-gop --opt-ref-list-length-pps --min-keyint 23 --bframes 16 --weightb --ref 5 --rc-lookahead 60 --lookahead-slices 0 --crf 16.90 --opt-qp-pps --cbqpoffs -2 --crqpoffs -2 --ipratio 1.30 --pbratio 1.20 --rd 4 --psy-rd 2.01 --rdoq-level 2 --psy-rdoq 2.01 --aq-mode 3 --no-cutree --vbv-maxrate 160000 --vbv-bufsize 160000 --hrd --vui-hrd-info --deblock=-3:-3 --no-sao --selective-sao 0 --no-mcstf --range limited --colorprim bt2020 --transfer smpte2084 --colormatrix bt2020nc --chromaloc 2 --hdr10 --hdr10-opt --sar 1:1 --output "C:\Users\cebol\Desktop\ENCODES\HYBRID\2024-09-17@14_43_08_5610_01.265"

=> seems like there is an unncessary space in the call generation.
I'll look at it after work today, should be easy to fix.

Cu Selur