I, P, B frames?

[striker9]

Where can I go to learn about what these are for? It is kind of hard to search for so I apologize if it has been asked already.

[yoda313]

Videohelp has a glossary for the most common video terms. Here you go:

https://www.videohelp.com/glossary

https://www.videohelp.com/glossary?I#I%20Frame

https://www.videohelp.com/glossary?B#B%20Frame

https://www.videohelp.com/glossary?P#P%20Frame

[sacajaweeda]

I, B & P frames are what make up a GOP sequence in an MPEG stream. Most editing & authoring software only lets you make cuts and add chapter points on an I frame, which is a full frame, rather than B and P frames which are like partial frames that have part of the previous frame and reading ahead to the next frame in the sequence. The better editors will let you make frame accurate cuts on any frame. This is a plus for editing MPEG streams as it gives you better control of where your breaks are and helps eliminate audio sync problems. You can control the number and sequence of frames within a GOP with the better encoders, telling it how many B or P frames to read agead before the next full or "I" frame in the sequence. The cheaper encoders don't give you that kind of control over it, and some even output nothing but I frames.

I used to have a link somewhere that goes into detail on this stuff but I can't find it at the moment. I'll see if I can dig it up.

[sacajaweeda]

http://www.digvid.info/tmpgenc/settings_gop.php