Yes, that’s a limitation of the video encoder. Without getting into too much detail, certain files can only store video a certain way. I suggest trying another one of the formats.
One more issue - the user can type in an own frame rate like 10 and it cause that a new duration is calculated, but the duration should kept and the frame count should be calculated. The length should not be changed.
Also I rendered a preview of my animation at 10fps. The bongo video creator doesn’t support mp4 with 10fps, but it should be possible since I can do it on the long way over a video software - MP4 supports a wide range of custom frame rates. @Joshua_Kennedy looks like it should be no big problem to support more frame rates.
Above I asked you to take a look at the Timemanager in Bongo’s WIP.
The idea is to modify the Render dialog (a job still to be done) so that if reflects the settings of the Timemanager plus the Output settings (output location, image format, video file format etc…). At that time we can look into the feasibility to add an option to bypass the ‘standard’ framerate.
Hope springs eternal.
Luc