HDV-Project / Compressor: I-Frame only…?

[Tim Kolb]

It’s greyed out correct?

It’s part of the settings. I-Frame only MPEG just takes some stress off the processor as it can be encoded sequentially.

TimK,

Kolb Productions,
Creative Cow Host,
Author/Trainer
http://www.focalpress.com
http://www.classondemand.net

[Uwe Lansing]

Yes, it

[Tim Kolb]

There were a couple of directions of development going on with this feature and what I do recall can’t necessarily be discussed…but MPEG in the form used in HDV is made up of I frames (complete) P frames (predictive…based on prediction from I frames) and B frames (bidirectional frames computed from I and P frames).

The sequence would flow by like this: IBBPBBPBBPBBPBBI (“I” signifies new GOP for 15 frame HDV2)

First the I frame is computed, then the next P frame, then the B frames in between them, then the next P frame, then the B frames in between…all the way to the point where the next “I” frame to start the next GOP is computed before the last two B frames of the first GOP can be created…

This is why video with the same data rate as DV handles like it’s about 5 times as much data with the same PC.

By using all I frames for your preview renders, they get done faster. PPro does not use preview renders for exports, so when you export to HDV, that is a separate procedure.

TimK,

Kolb Productions,
Creative Cow Host,
Author/Trainer
http://www.focalpress.com
http://www.classondemand.net

[Uwe Lansing]

Thank you Tim

regards
Uwe