Simple algorithms for rational time speed playback of a standard video sequence

We present very simple but effective algorithms to playback a standard video tape recording at a higher/slower rational time speed in accordance with varying demand. To avoid temporal signal sampling errors for a slow speed playback and spatial ones for a high speed one, the following four-step algorithms have been developed: (1) sequences are separated into even and odd fields, and intermediate noninterlaced frames are made by vertical interpolation; (2) for slowing down the playback speed of video sequences, linear interpolation between two frames surrounding a fractional frame position is used; (3) for speeding up, an average frame in a window surrounding the desired frame (with the window size depending on the speed up factor) is used; (4) sequences are post processed by decimation to get back interlaced images. The proposed algorithms give quite smooth sequence images for slow speed sequences and nondiscontinuous and less jittering ones with appropriate motion blur for high speed ones.