x264 encoding error.

[hjatsu]

Good news, sort of.. 

I did not have time to test on another hardware yet but I did some more tests with the current one, based on the hypothesis of crash happening at around the x264 lookahead value, so when input material is ending. Here are my results, all repeatable at least 3/3 times:

--sync-lookahead 200 --rc-lookahead 200

Crash at 456/858 (402 frames left) --> About double of the lookahead values. Note bobbed deint.

--sync-lookahead 10 --rc-lookahead 10

Crash at 814/858 (44 frames left) --> Noticeably smaller than the previous setting.

--sync-lookahead 10 --rc-lookahead 200

Crash at 646/858 frames (212 frames left). --> Again mirroring the order of magnitude change in the lookahead values.

--sync-lookahead 200 --rc-lookahead 10

Crash at 624/858 frames (234 frames left). --> Very similar to the above.

Example of all the encode arguments:

tool: C:\Program Files\Hybrid\64bit\x264.exe
argumentString(1): --preset veryslow --crf 14.50 --profile high --level 5.1 --sync-lookahead 10 --rc-lookahead 200 --no-fast-pskip --vbv-maxrate 300000 --vbv-bufsize 300000 --deadzone-inter 6 --deadzone-intra 6 --threads 4 --sar 16:15 --non-deterministic --range tv --colormatrix bt470bg --demuxer y4m --input-range tv --fps 50/1 --output-depth 8 --output "C:\Users\hjatsu\Desktop\vhs\temp\2024-08-18@10_49_41_8510_06.264" -

Then I proceed to test if OpenCL is to be blamed, so tried this:

# Deinterlacing using QTGMC
clip = havsfunc.QTGMC(Input=clip, Preset="Very Slow", TFF=True) # new fps: 50

...instead of this:

# Deinterlacing using QTGMC
clip = havsfunc.QTGMC(Input=clip, Preset="Very Slow", TFF=True, opencl=True, device=1) # new fps: 50

And the result was that the test jobs FINISHED successfully 6/6. So using CPU for everything seems to be the trick?!


Decided to also test with the iGPU, so modified the OpenCL jobs a little by pointing the device param to my Intel Iris Xe instead of Nvidia RTX 3500:

# Deinterlacing using QTGMC
clip = havsfunc.QTGMC(Input=clip, Preset="Very Slow", TFF=True, opencl=True, device=0) # new fps: 50

And the result was exactly the same as with GPU, crashes happening at exactly the same frames.


So my take from this is that the issue must be either:
- Vapoursynth/QTGMC OpenCL implementation
- GPU drivers (unlikely because iGPU crashes too)
- Something in my system interfering with all GPU operations (no idea if even possible and what this could be)

This finding does not fully explain the crashes I observed with the initial jobs, when I was using the latest stable version that was unable to recognize my RTX 3500. But based on this test session, my only option is to just use CPU for everything I guess...?