There's a little mess with SVP libs versions and MT mode 1 support.
- all pre-Vapoursynth libs are MT mode 2 only
- builds 128 - 132 are compatible with MT mode 1 BUT there's a mysterious memory corruption somewhere in svpflow2 which gives us that error
- as a temporary fix we released svpflow2.dll .135 as an old (pre-VS) version upgraded for the latest SVP Manager, so it is NOT compatible with MT mode 1
The script with SetFilterMTMode("SVSmoothFps", 1) using svpflow2.dll ver.135 will definitely freeze on start.
However I really don't see any improvement in using MT mode 1 with build 132 libs.
Here's how it works:
"old" Avisynth-only libs in MT=2: N instanes of AVS's VideoFilters running at the same time.
"new" multi-platform libs contain a platform-independent thread-safe "cores"
- Vapoursynth: 1 thread safe VS filter uses 1 "core"
- Avisynth MT=2: N single-threaded VideoFilters share 1 thread safe "core"
- Avisynth MT=1: 1 thread safe VideoFilter uses 1 "core" - just like in Vapoursynth version
The point is there's just one "core" is all cases.