Unclear thread safety requirements for plugins

[e00E]

Plugins implement several functions that can be called by obs. I was unable to find any specification on which functions can be called by multiple threads or in parallel. This is problematic because if plugin authors assume single threading and multi threading happens we get undefined behavior. On the other hand if single threading is guaranteed it would make implementations easier.

For a specific example consider an encoder plugin. We do not know whether update and encode might be called in parallel but this is very relevant for the implementation.

A possible place for this documentation is https://obsproject.com/docs/plugins.html .