L64005 MPEG-2 Audio/Video Decoder Technical Manual
1-17
Final Rev F
Copyright 1996 by LSI Logic Corporation. All rights reserved.
Temporal Redundancy. Compressible repetition in motion video
between frames.
Transform Coding. Maps statistically dependent pixels to independent
coefcients.
Variable-Length Coding. Encoding that creates codewords of variable
numbers of bits. See
Huffman coding.
VBI. Vertical blanking interval.
YUV. Color space used in PAL. Y is luminance; U and V are the 1.3-MHz
color difference (U =Y–R and V = Y – B) chrominance components.
Zigzag Scanning. This method reorders data by reading it in diagonal
order from upper left (0, 0) to lower right prior to run-length coding.
1.5
System
Overview
The L64005 is specically designed for use in digital audio and video
decoding systems based on the MPEG-2 algorithm (herein referred to as
MPEG). The device may be considered a “black box” that receives coded
audio and video data and produces a decoded audio and video data
stream. LSI Logic has optimized L64005 input/output interfaces for low-
cost integration into an embedded application. The L64005 core logic is
based on the proven L64002 MPEG-2 Video Decoder. The system block
diagram in
Figure 1.7 shows how an audio/video decoding system uses
the L64005.
1.5.1
Video Decoding
The L64005 operates optimally at image sizes up to 720 x 480 pixels,
with a frame rate of 30 fps (720 x 576 @ 25 fps for PAL). This is some-
times referred to as “main level, main prole” of MPEG-2. As such it can
also decode MPEG-1 sequences. The coded data channel may have a
bit rate of up to 20 Mbit/s for serial, and 40 Mbit/s for parallel. The
L64005 supports image resolutions up to 720 x 480 in dimension multi-
ples of 16 pixels. As the resolution decreases, the amount and bandwidth
of DRAM memory required for frame stores also decreases.
1.5.2
Audio Decoding
The L64005 also integrates an MPEG audio decoder (MUSICAM). The
audio decoder is capable of decoding two channels of MPEG audio
Layer 1 or Layer 2 over the full range of compliant bit rates and sample
rates. The audio decoder uses the same external memory as the video