For the benefit of anyone reading this thread, I just ran a couple of tests which partially agree with the above. Setting the frame rate explicitly using the options --fps 24000/1001 --force-cfr does encode using the target frame rate (despite x264 implying otherwise). However, for the source file I am using at least, not specifying the frame rate still results in the default 25 fps being used. This seems to be at odds with what's stated in the settings info. It may be something to do with the source file being an elementary .264 stream. Either way, the fact that x264 reports 25 fps irrespective of source fps is somewhat confusing.