Why write_videofile() param 'threads=' does not work on windows?

Why write_videofile() param ‘threads=’ does not work on windows? I tested this code on a 48 cores windows server:

ThreadCount = multiprocessing.cpu_count()
bk_clip.write_videofile(output_file_name, fps=VideoFps, audio=False, logger=None, threads=ThreadCount)

There are only 3 ffmpeg.exe appears in the task list as below

But this server is Intel Xeon E5-2678 v3 @ 2.50GHz, 2cpu * 12 cores = 24 cores.

It supposed to be 24 threads, but I only found 3 ffmpeg.exe

[tburrows13]

I agree that I would love to have an improved speed in MoviePy. Unfortunately, MoviePy is very limited by the number of active contributors (at the moment, only me). For the time being, I am working on changes that increase the usability and stability (both of which have been lacking for some time), which I think are more important at the moment, because once improved, they should reduce the ‘community’ work, such as handling bug reports and questions. It also makes it easier to add new features in the future if the existing code is stable.

For improving performance, there are the following things to take into account:

• Video processing is inherently slow because it will can only run on the CPU
• Python is inherently slow
• Multi-threading should speed it up, but I only have a dual-core laptop for development so it will be hard for me to analyse performance improvements.

I can’t give a timeline, because (assuming that it is me that is still managing it), it entirely depends on how much time I am willing to give to this project, which depends on how much I am enjoying it. Sorry.

Like I said earlier, if someone else who really priorities speed comes and works on that, then I’d be happy to review and merge that code (which is what happened in #1157 - will be merged soon).

[jmoraispk]

I just want to leave a ‘Thank you’ note here. Although it is somewhat slow, it is far more practical than anything else I’ve tried. The time it takes rendering has far been compensated by the time it saves to code. And rendering does not require effort! So, thank you @tburrows13 for all the work.