Compression: MPEG interframe

• I frames are reference frames, that are fully encoded using a DCT-based scheme.
• P frames are predicted from the previous I or P frame.
• B frames are bi-directionally interpolated from the nearest I or P frames.
• Frame size decreases from I to P to B frames.
• Reverse playback requires buffering so that all frames needed to decode a frame are saved as long as they are needed.