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 if the "DirectShow File
Multimedia Reader" priority is set to 1 in the "Enviromental settings"
(VFAPI plug-in). With this setting, I get jerks in the MPEG-2 file in
scenes moving quickly.

When this filter's priority is set to 0 or -1 (default), the jerks are
gone, but there is no sound (MP3 inside a DivX) either.

Two possibilities ...

1. How can I get rid of the jerks with this filter's priority set to 1?
2. How can I get sound while this filter's priority is left at -1?

Many thanks!