Rocketman, are you talking about operating FFmpeg externally?
I have a new working version of my script btw;
filepath = “E://Directory//Directory//Directory//Directory//Directory//Directory//output//”
os.system("ffmpeg -i "+ filepath + “IMAGESEQUENCE_%04d.png” + " -c:v libvpx -b: 1500k -r 60 -metadata:s:v:0 alpha_mode=“1” -y -auto-alt-ref 0 " + filepath + “OUTPUTMOVIE.webm”)
print(filepath + “IMAGESEQUENCE_%04d.png”)
The next trick for me is to find out how to make it point to the user defined filepath in blender’s output settings. Then, get the image and movie names to match the user defined names.
Maybe also, I’ll include the task of checking which temp directory to render the png/exr sequence to. Third step is creating some gui that calls the script in the output panel, and adding the FFMPEG commands responsible for forcing vp8, (libvpx). After all, this is how I wish it was in the first place.
So I’d change ‘WebM/VP9’ to ‘WebM’, and simply have a exclusive radiobox option that says ‘VP8’, and one that says ‘VP9’, and it just by default sits on ‘VP9’ unless the user switches it. When it switches, the options compatible with the other version disappear/reappear as needed.