Graphics Reference
In-Depth Information
prediction structure which allows greater control over the drift effect associated with
closed loop video coding approaches
[41].
Bit-streams with temporal scalability can be provided by using hierarchical prediction
structures. In these structures, key pictures are coded at regular intervals by using only
previous key pictures as references. The pictures between the key pictures are the hier-
archical B pictures which are bi-directionally predicted from the key pictures. The base
layercontainsasequenceofthekeypicturesatthecoarsestsupportedtemporalresolution;
while the enhancement layers consist of the hierarchically coded B pictures (see Figure
3.4). A low-delay coding structure is also possible by restricting the prediction of the en-
hancement layer pictures from only previous frame.
