L64105 LSI Logic Corporation, L64105 Datasheet - Page 399

• Manufacturer Part Number: L64105
• Description: Mpeg-2 Audio/video Decoder
• Manufacturer: LSI Logic Corporation

A.1.2 Bitstream Syntax
The MPEG standard specifies the syntax for a compressed bitstream.
The video syntax contains six layers, each of which supports either a
signal processing or a system function. The layers and their functions are
described in
Table A.1
The MPEG syntax layers correspond to a hierarchical structure. A
sequence is the top layer of the video coding hierarchy and consists of
a header and some number of groups-of-pictures (GOPs). The sequence
header initializes the state of the decoder so that it is not affected by past
decoding history.
A GOP is a random access point, that is, it is the smallest coding unit
that can be independently decoded within a sequence. The GOP
consists of a header and some number of pictures. The GOP header
contains time and editing information.
The three types of pictures as explained earlier are:
Because of the picture dependencies, the bitstream order (the order in
which pictures are transmitted, stored, or retrieved) is not the display
order but rather the order in which the decoder requires the pictures for
Video Compression and Decompression Concepts
Syntax Layers
Sequence Layer
Group of Pictures Layer
Picture Layer
Slice Layer
Macroblock Layer
Block Layer
I pictures
P pictures
B pictures
Table
MPEG Compressed Bitstream Syntax
A.1.
Function
Random Access Unit: Context
Random Access Unit: Video
Primary Coding Unit
Resynchronization Unit
Motion Compensation Unit
DCT Unit
A-5