AviSynth Script Exporting causes FFMPEG and Virtualdub to stall

[Tek03]

Hi everyone

For some weeks I've been experiencing some annoying issues while exporting almost any long-file-AviSynth script via FFmpeg (via cli, VirtualDub2 or Avidemux):
while exporting to x264 or x265, the encoding stalls and never resumes, like this:

I attempted some tweaking, like moving the source file to an NVMe drive, but with no results. Same after fresh-reinstalling the operating system, but this time Windows 11.

Here are some details:
The script is the one shown below. It takes a 37-minute sample YUY2 clip captured from a VHS, which gets some denoising, sharpening, QTGMC deinterlacing and 1080p upscaling.


I've then dragged the script into VirtualDub2 to encode it to x265 with the following settings:


The encode goes on for some minutes, but then it stops and remains still on the progress bar... It completes the job for small videos, but it can't hold full vhs captures. I even tried changing the source codec from YUY2 to Lagarith... I couldn't event find any info about this online, and the same thing occurs while exporting in x264 with my other 720p script.

Hope you can help me, otherwise I won't be able to go on with my digitising work.

[poisondeathray]

If you have avstp.dll in the plugins folder, try moving it or delete it . Some people report this as the multithreading hanging culprit for avs+

Not related to the "hanging", but you should use ConvertToYV12(interlaced=true), otherwise the YUY to YV12 downsample can have chroma artifacts

[Tek03]

If you have avstp.dll in the plugins folder, try moving it or delete it . Some people report this as the multithreading hanging culprit for avs+

Thank you! Now it doesn't stall anymore, but now it gets to 20-30% cpu usage


By the way it completed the 720p script, but now it does run single-threaded as I understand, and that's a pity considering I have a 4C/8T i7.
I'm reading how to enable multithreading on the AviSynth wiki. It's pretty chaotic, so if I'll find a solution I'll write back!

Not related to the "hanging", but you should use ConvertToYV12(interlaced=true), otherwise the YUY to YV12 downsample can have chroma artifacts

Thanks, now I've corrected it!

[poisondeathray]

pinterf was looking into the manalyze bug with mt and avstp.dll, but I don't think there was a final solution yet.

The options for systems that are affected (it seems not everyone is affected either...not sure why...) are to either remove avstp.dll, or set all manalyze instances to mt=false - this means editing each individual .avsi script dependency)

https://github.com/pinterf/mvtools/issues/46
http://forum.doom9.net/showthread.php?p=1914018#post1914018

It's important to look at the FPS along with the CPU% . You can have high CPU% usage , but "thrashing" and wasted cycles resulting in low FPS . If you had to look at one measure, the FPS is more important than CPU%


Other options are to use simultaneous single threaded encodes if you have enough resources, or to use vapoursynth which has automatic and more stable threading than avisynth

[Tek03]

pinterf was looking into the manalyze bug with mt and avstp.dll, but I don't think there was a final solution yet.

The options for systems that are affected (it seems not everyone is affected either...not sure why...) are to either remove avstp.dll, or set all manalyze instances to mt=false - this means editing each individual .avsi script dependency)

https://github.com/pinterf/mvtools/issues/46
http://forum.doom9.net/showthread.php?p=1914018#post1914018

It's important to look at the FPS along with the CPU% . You can have high CPU% usage , but "thrashing" and wasted cycles resulting in low FPS . If you had to look at one measure, the FPS is more important than CPU%


Other options are to use simultaneous single threaded encodes if you have enough resources, or to use vapoursynth which has automatic and more stable threading than avisynth

That's a bit too advanced for me!
I just meant to do some restoration via AviSynth, I don't have the time to dig so further, but thanks anyway for the info!