MPEG Coding GOP

Question

I am trying to figure out how GOP works

Consider the uncoded frame sequence:

I B B P B B P B B P B B I B B P B B P B

I understand what The N(GOP) is,

Answer 1

Check out this MPEG compression FAQ, particularly the section "Q. So is each frame predicted from the last frame?" for a more detailed discussion of these exact questions.

Straight answers:

1. Since both I and P need to be decoded before either of the intervening B frames can be decoded, P is necessarily transmitted before either of the first 2 B frames. Therefore, the reordered sequence would look like: I P B B P B B P B B B B I ..
2. Eschew B frames in favor of all P frames for interframes, or drop interframes entirely and go for all I frames.
3. Use more B frames and longer GOPs (I frames are the largest frames).
4. If a frame's data is corrupted, errors can creep in. If other frames depend on the corrupted frames, errors can propagate through other frames.