I've used mencoder's speed parameter to generate a video which is played at half the speed. This basically means halving the framerate of the video. But I'm interested in software that could convert a 30fps video to another 30fps video with half the frames interpolated, maybe using the motion information stored in the video stream per se. I think this is called intra-frame interpolation, but I haven't found anything practical other than research papers.
Any pointers to such software?