This is a sample video of Avatar. The original video is 24fps, but somehow it was re-rendered into 60fps, and it looks absolutely natural.
please, tell me how can i do such kind of things? Which software can increase the fps like this sample?
optical flow plugins such as ae's timewarp, RE:Vision Effects' twixtor, fcp's cinema tools can all warp in extra frames to increase/decrease the framerate smoothly, but they are not perfect and often require masks and splines to get good results.