Multithreading QTGMC with AviSynth+

[ZetaStax]

Hello, newbie here hope you don't mind

I've encoding videos using ffmpeg and a supplied avisynth+ script in order to leverage the power of qtgmc for deinterlacing. The results are great, but the encoding performance is a little underwhelming so to speak. I've been trying to enable multithreading but it doesn't seem to have any effect... Here's my script

Import("multithread.avsi")
LoadPlugin("C:\Program Files (x86)\AviSynth+\plugins64+\ffms2.dll")
FFMPEGSource2(".\title_t05 (1)-001.mkv")
AssumeTFF()
SetFilterMTMode("QTGMC", 2)
QTGMC(preset="Slower", EdiThreads=5)
Prefetch(8)

The mulithread.avsi script is the one mentionned here http://avisynth.nl/index.php/AviSynth%2B#Help_filling_MT_modes
It doesn't matter if I use 5 or 2 EdiThreads, and Prefetch does not make any difference either. Am I doing something wrong or is this the best performance I can get? I have a i7 8700 cpu by the way, and encoding speed for x264 on veryslow preset is x0.5 versus x2.1 using Handbrake and Decomb on LessSensitive, for comparison.

[jagabo]

How much CPU usage are you getting? And what frame size? With a 1080i source on my i5 2500K I'm seeing over 2 fps with that script and x264 CLI at the veryslow preset, near 100 percent CPU usage. Note that the script alone (no encoding) runs around 7 fps.

[ZetaStax]

I'm seeing 100% cpu usage, but I'm not confident on how optimized that workload is. I am encoding 480i content, and encoding runs at about 30 fps I would say (I don't have the exact figure displayed, only the ratio, how can I see that with ffmpeg?)

[jagabo]

QTGMC is much slower (and much better quality) than any of Handbrake's deinterlacers. Keep in mind that your 0.5x is relative to a 60 fps video, ie, it's encoding at 30 fps. On my old i5 I get around 18 fps using you settings on 480i video. So your 30 fps is in the ballpark of what I'd expect to see out of an i7 8700.

[ZetaStax]

Indeed QTGMC is giving amazing results, so I don't mind waiting a little more. Thank you for your help!

[jagabo]

Even at the "fast" preset it usually looks pretty good.