ΔΣ Signal Compression Using Adaptive Conversion Tables
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Solution Overview
Problem
Current lossless compression technologies for ΔΣ-modulated digital signals, such as DSD data, are not suitable for general embedded CPUs and do not offer a high enough compression rate for efficient processing, especially in mobile terminals.
Innovation Solution
A compressive encoding apparatus and method that converts M bits of a ΔΣ-modulated digital signal into N bits (M > N) using a first and second conversion table, where the tables store codes with higher generation frequencies for past bit patterns, enabling efficient encoding and decoding even in general embedded CPUs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If 1-bit signal processing is used for DSD data compression, then lossless compression is achieved, but processing cannot be performed in general embedded CPUs and high throughput is required
Solution Approach 1:
The patent segments the DSD data processing into fixed 4-bit units and uses pre-generated conversion tables for each possible past bit pattern state. This segmentation transforms the complex 1-bit signal processing into discrete, manageable table lookups that can be efficiently executed on general embedded CPUs without requiring specialized hardware.
Solution Approach 2:
The patent performs preliminary action by pre-generating conversion tables that map past bit patterns to optimal current bit patterns before processing begins. These tables are created offline and stored for rapid lookup during compression, eliminating the need for complex real-time calculations on the embedded CPU and enabling high throughput software processing.
2Reliability
If existing lossless compression technology is used for DSD data, then compression is achieved, but the compression rate is not high enough
Solution Approach 1:
The patent implements feedback by continuously monitoring the past bit patterns and using this historical information to dynamically select the most appropriate conversion table. The system feeds back the actual compression results and adjusts table selection to maximize compression rate while maintaining lossless reconstruction, achieving both high compression ratios and reliable decompression.
Solution Approach 2:
The patent introduces dynamics by making the conversion table selection adaptive rather than static. The system dynamically switches between different conversion tables based on the actual bit pattern sequences encountered in the input signal, allowing the compression algorithm to optimize its performance for different types of audio content and achieve higher overall compression rates.
Data Source
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AI summary
The present disclosure relates to a compressive encoding apparatus, a compressive encoding method, a decoding apparatus, a decoding method, and a program which can provide a lossless compression technology having a higher compression rate. An encoding unit of the compressive encoding apparatus converts M bits of a ΔΣ-modulated digital signal into N bits (M > N) with reference to a first conversion table, and when the M bits are not able to be converted into the N bits with the first conversion table, converts the M bits into the N bits with reference to a second conversion table. When the number of bit patterns of the N bits is P, the first conversion table is a table storing (P-1) number of codes having higher generation frequencies for past bit patterns, and the second conversion table is a table storing (P-1) number of codes having higher generation frequencies for past bit patterns, which follow those of the first conversion table. The present disclosure is applicable to a compressive encoding apparatus that compressively encoding an audio signal, and the like, for example.