I think framerate at playback depends on (the settings used when encoding) the movie played.
What is your intended purpose/goal?
What filters/codecs is BS.Player using for your file(s)?
Maybe the filter used has such possibility.
You can find out which filters/codecs BS.Player uses for playback of a specific file by checking under ..
.. (rightclick >) Options > Filters > Advanced.
Clicking on
source and/or on the small [+] signs in front of the codecs/filters shown will reveal further info of and access to those filters/codecs.
(P.S.: Playback rates can be selected under rightclick > Playback > Playback rate Alternatively you can use shortcut keys, such as e.g. [F5] and [F6] which result (by default) in an increase resp. decrease of playback speed by 1% and in combination with [Shift] by 10%. Note that these keycombinations can be used repeatedly to get an accumulated result.)