Variable-Length Code Decoding with Adaptive Table Bit Clipping
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Solution Overview
Problem
Existing variable length code decoding methods require large decoding process tables and suffer from inefficiencies due to fixed bit length clipping, leading to increased table size and processing delays, as they fail to adjust the trade-off between table size and processing performance effectively.
Innovation Solution
A variable length code decoding device that uses multiple decoding process tables with entries containing flags for completion or continuation, allowing dynamic adjustment of bit length clipping and table references, enabling flexible table size and processing performance optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed bit length (m bits) is used for decoding process table reference, then the decoding structure is simplified, but the table size increases and processing performance deteriorates
Solution Approach 1:
The patent applies dynamics by making the bit length for table reference adjustable rather than fixed. The decoding device dynamically selects the bit length (n bits) based on the actual code word length and decoding requirements, allowing the system to adapt between using fewer bits for common cases (reducing table size) and using more bits when needed (improving processing efficiency).
Solution Approach 2:
The patent changes the parameter of bit length from a fixed value (m bits) to a variable parameter that can be adjusted according to decoding needs. By allowing n to vary between 1 and m based on code word characteristics, the system optimizes the trade-off between table size and processing speed without being constrained by a predetermined fixed length.
2Volume of stationary object
If the clipping bit length is shortened to reduce table size, then the table memory size decreases, but the number of table lookups increases causing processing delay
Solution Approach 1:
The system dynamically adjusts the clipping bit length based on the specific decoding situation rather than using a fixed short length. When code words are long, it uses longer clipping lengths to reduce lookup次数; when code words are short, it uses shorter clipping lengths to keep table size manageable. This dynamic adjustment resolves the contradiction between table size and processing efficiency.
Solution Approach 2:
The patent segments the decoding process into multiple stages with different clipping bit lengths. Instead of uniformly using a short clipping length throughout, it divides the decoding into phases where earlier stages may use longer clipping to reduce lookups, and later stages use shorter clipping when the remaining code word portion is small, optimizing both table size and processing speed.
3Ease of operation
If a fixed clipping bit length is used for all table references, then the decoding process is simplified, but it cannot adapt to different code word lengths leading to increased table size
Solution Approach 1:
The patent introduces dynamics by making the clipping bit length adaptive rather than fixed. The system automatically adjusts the clipping length based on the actual code word length and decoding progress, maintaining simple decoding operations while preventing table size inflation that would result from using a uniformly fixed clipping length.
Data Source
AI summary
A variable length code decoding device for decoding variable length code data, including: a table memory that stores a plurality of decoding process tables having a reference relationship therein; and a decoding control unit that is given a start address and an initial reference bit length of the table memory; and sequentially selects the decoding process tables according to the decoded data to control a process of decoding the variable length code data, wherein when referring to the decoding process table to perform an initial decoding of the variable length code data, the initial decoding process is conducted by a longer bit length to be clipped from the variable length code data for referring to the decoding process table than the bit length used when referring to the other portions of the decoding process table.