Editing Inter frame (section)

==Frame types==
The difference between P-frames and B-frames is the reference frame they are allowed to use.

===P-frame===
P-frame is the term used to define the forward Predicted pictures. The prediction is made from an earlier picture, mainly an I-frame or P-frame, so that require less coding data (≈50% when compared to I-frame size).

The amount of data needed for doing this prediction consist of motion vectors and transform coefficients describing prediction correction. It involves the use of [[motion compensation]].

===B-frame===
B-frame is the term for bidirectionally predicted pictures. This kind of prediction method occupies less coding data than P-frames generally (≈25% when compared to I-frame size) because the prediction is made from either an earlier frame or a later frame or both them. (B-frames can also be less efficient than P-frames under certain cases,<ref>{{Cite web|url=https://forum.doom9.org/showpost.php?p=1228631&postcount=12|title = Doom9's Forum - View Single Post - x264 Lossless question}}</ref> e.g.: lossless encoding.)

Similar to P-frames, B-frames are expressed as motion vectors and transform coefficients.
In order to avoid a growing propagation error, B-frames are not used as a reference to make further predictions in most encoding standards. However, in newer encoding methods (such as [[H.264/MPEG-4 AVC]] and [[HEVC]]), B-frames may be used as reference for better exploitation of temporal redundancy.<ref>{{Cite web |title=Hierarchical B-Frames or B-Pyramid - Video Compression |url=http://www.ramugedia.com/hierarchical-b-frames-or-b-pyramid |url-status=dead |archive-url=https://web.archive.org/web/20170615034729/http://www.ramugedia.com/hierarchical-b-frames-or-b-pyramid |archive-date=2017-06-15 |access-date=2019-03-24 }}</ref><ref>{{cite web |url=http://mewiki.project357.com/wiki/X264_Settings#b-pyramid |title=X264 Settings - MeWiki |website=mewiki.project357.com |access-date=12 January 2022 |archive-url=https://web.archive.org/web/20141118124738/http://mewiki.project357.com/wiki/X264_Settings#b-pyramid |archive-date=18 November 2014 |url-status=dead}}</ref>