Is it possible to set the frame rate of the transcoded streams? I see that you can set the keyframe intervals, but if incoming streams use a different framerate, then the keyframes can't be controlled reliably. For example, a stream with 30fps and a keyframe interval of 60 means one every 2 seconds, but a stream with 15fps has a keyframe every 4 seconds.
There is an ambiguous option that might allow it, but I haven't found any more clues about what's possible with it:
"Video/Parameters: Implementation-specific encoding parameters that control the encoding process (this feature will be documented later)."