CAPTURING WITH I FRAMES ONLY

[GLADIATOR 2002]

Can anyone tell me if there is an advantage capturing with I frames only in MMC 6.3 for MPEG1 OR MPEG2? What are the advantages or disadvantages. I know that there are also options for capturing for single field or both fields, what are the advantages and disadvantages.

[Darkbird]

I frames are like keyframes, all the picture information for a frame is stored in that frame. Simplifying somewhat, P frames and B frames store predicted motion and the difference between frames. So theoretically, capturing with only I frames will result in better quality. However, I frames can only take advantage of picture compression similar to jpeg, so captured file sizes will be much much larger.

[Anonymous65]

The big advantage of I-frames only is that you can edit the file as an AVI file, frame accurate without having to decode and re-encode the mpeg file. If you want to edit a "normal" mpeg file, the edit point will be something like +/- 7 frames, out of your control, unless you decode and re-encode the mpeg file. But to get good quality with I-frames only, use the maximum bitrate you can record at. Mpeg I-frames is almost like Mjpeg compression.