About MPEG Compression

Temporal Compression Instead of storing complete frames, temporal (interframe) compression stores only what has changed from one frame to the next, which dramatically reduces the amount of data that needs to be stored while still achieving high-quality images. Video is stored in three types of frames: a standalone I-frame that contains a complete image, and then predictive P-frames and bipredictive B-frames that store subsequent changes in the image. Every half second or so, a new I-frame is introduced to provide a complete image on which subsequent Pand B-frames are based. Together, a group of I-, P-, and B-frames is called a group of pictures, or GOP. HDV uses a long-GOP pattern, which means that there is at least one Por B-frame for each I-frame.