The output of the decoding process, for interlaced sequences, consists of a series of fields that are separated in time by a field period. The two fields of a frame may be coded independently (field-pictures) or can be coded together as a frame (frame pictures).
The diagram 4.15 shows the intra, predictive and bi-directional frames that MPEG supports:
An MPEG source encoder will consist of the following elements:
