I use TMPGEnc frequently and never experienced the problem below.

As source, I use a 25 fps *.avi file. However the frame rate in the
"Source range" window of TMPGEnc shows 30 fps (top left of the window) if the "DirectShow File Multimedia Reader" priority is set to 1 in the "Enviromental settings" (VFAPI plug-in).

When this filter's priority is set to 0 or -1 (default), the "Source range" shows 25 fps (top left of the window).

Can someone confirm (and possible explain) this?

TIA