Survey of Dirac: A Wavelet Based Video Codec for Multiparty Video Conferencing and Broadcasting - Intelligent Video Event Analysis and Understanding - page 233

motion information estimated at the encoder also uses statistical modeling and
arithmetic coding to compress it into the fewest number of bits. This compressed
data is put into the bit stream, to be used by the decoder as part of the compressed
video [8].

5.4.4 Dirac Bit Stream Syntax

Dirac bit-stream syntax structure is shown in Figure 17 (a ,b) for both intra and
inter frames. It starts with sequence header. Sequence header starts with start of
sequence code. The sequence header repeats itself after 10 frames for intra frame
coding and after one group of pictures (GOP) for inter frame coding. Each
sequence header and frame is treated as a parse unit.

(a)

(b)

Fig. 19 Bit stream syntax (a) Intra Frame (b) Inter Frame

The first thirteen bytes of parse unit consists of start of parse unit (BBCD),
parse code, next parse unit size and previous parse unit size as shown in Figure 18.
The different parse codes related to start sequence, end of sequence, intra non
reference picture arithmetic coding, intra reference picture arithmetic coding and
inter reference picture arithmetic coding have been shown in Table 2.

Table 2 Parse code table

Parse
Code

Description

0x00 Sequence header

0x10 End of sequence

0x0C Intra Reference Picture (arithmetic

coding)

0x08 Intra Non Reference Picture (arithmetic

coding)

0x0D Inter Reference Picture (arithmetic

coding)