mpeg - Are B, P frames results of the motion estimation/compression?

Question

Confused about the relationship between MPEG frames and motion estimation/compensation :(

Are B, P frames results of the motion estimation/compression? But motion estimation/ compression use those frames. Then how and who decide the frames?

Answer 1

There are actually 3 types of frames:

• I-frame Intra-coded (independent) frame, the least compressed
• P-frame Predicted frame: uses precedent frames to improve compression
• B-frame Bi-directional frame: uses both previous and next frames for the best compression

These frames are indeed the result of compression by the encoder, which is done in different steps, roughly (not exhaustive):

• Reduce color nuances & resolution of images
• Remove imperceptible details
• Compare adjacent images and remove redundant informations (i.e. unchanged items between 2 images)
• [...]

There is a good article on wikipedia. You can find more asking google on I/P/B frames ;)

Also checkout this answer related to your question.