It’s quite unclear who exactly is asking for help with what.
My best guess is that someone tried to install opentimelineio in Blender 2.93, but there is no binary wheel for Python 3.9, only Python 3.7. That led to them trying to build it from source, which doesn’t work well with Blender’s bundled Python version. But users shouldn’t be having to do that in the first place, since they’d have to install Visual Studio, CMake, etc.
Much of what JT Nelson said in Slack is also just wrong information, I replied there to try to correct it.
I agree with you, that the best way would be, if they provide a wheel, the Félix David Blender OTIO add-on by could install directly, but I can’t tell you why this wheel-build is causing trouble in a way, that they are now trying a different way, which apparently needs the additional python headers mentioned here: Resolve installation into Blender · Issue #987 · PixarAnimationStudios/OpenTimelineIO · GitHub
They have been trying to solve this Blender/windows installation problem for more than a year now, which is why I’ve come to the conclusion, they’ll need some help from BF, if OTIO for Blender isn’t going to be abandoned. So, thanks again for spending your time on this.
Binary wheels work for blenders python however, on windows there are a few if then and buts, that we could have better guidance on.
when you have the .zip version of blender all is well, when you pick up blender from the windows store or use the msi installer things get a bit more difficult since the folders blender install into are heavily sandboxed and only administrators have write permissions to them usually.
Given pip will try to install into those folders, that be a problem, telling pip to install into the user home folder, sidesteps the issue.
The relevant tracker ticket here is T71420 for an essentially cut/paste ready solution see this post in that topic by user Roman Markov (unwave)
it’s like 650k of headers, compresses down to 220k or so, we already have the headers in SVN since we require them to build blender, so it should be a matter of adding them into the install section of creators cmakelist and off we go.