Survey of Dirac: A Wavelet Based Video Codec for Multiparty Video Conferencing and Broadcasting - Intelligent Video Event Analysis and Understanding - page 240

Fig. 29 Spatial Scalability
7.1.3 Temporal Scalability
Temporal Scalability allows you to reconstruct video using few numbers of
frames. It is achieved by using bi-directionally predicted frames or B-frames.
Temporal enhancement layers increase the frame-rate of the reproduced video by
coding additional pictures.
7.1.4 Implementation Details in Dirac
In Dirac Wavelet In Dirac Wavelet Based Video Codec, the bit stream generated
by encoder is splitted into 3 streams while keeping the header information in first
stream as shown in Figure 30 . Dirac encoder generates the encoded bit-stream of
16 bands, the Layer1 contains data for band 7-16 and all the header information of
frame and sequence. It is independently decodable and is called base layer. Layer2
contains the bands from 4 to 6 and layer3 contains the bands from 1 to 3. Layer2
and layer3 are not independently decodable and are called enhancement layers.
Each enhancement layer maintains the parse unit first thirteen bytes as shown in
Figure 20 . The layers of the bit stream for both intra nd inter frames after splitting
are as shown in Figure 31(a,b). Note that the motion vector data and header
information for inter frame are placed in the base layer.