Adaptive Audio Entropy Coding for Zero-Run Compression

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Solution Overview

Problem

Conventional audio encoding techniques face challenges in efficiently compressing high-quality audio data, leading to high bitrate requirements that consume significant storage and transmission resources, while also introducing audible noise due to lossy compression methods.

Innovation Solution

The implementation of adaptive entropy encoding and decoding techniques, including variable-dimension vector Huffman encoding, context-based arithmetic coding, and multi-mode coding, which switch between direct and run-level encoding modes based on audio data characteristics to optimize bitrate and quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If conventional audio encoding techniques are used to compress high-quality audio data, then bitrate reduction is achieved, but audible noise is introduced and audio quality deteriorates

Engineering Contradiction:
ImprovebitrateVSAvoidaudible noise
Core Design Contradiction:
Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The encoder dynamically switches between different encoding modes (direct Huffman encoding and run-level encoding) based on the characteristics of the audio data. This adaptive approach allows the system to optimize between compression ratio and quality preservation by selecting the appropriate encoding strategy for different data patterns, thereby reducing bitrate while minimizing audible noise.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention changes encoding parameters by using variable-dimension vectors in Huffman encoding and adapting between different coding schemes. By modifying how audio coefficients are grouped and encoded (using vectors of varying dimensions), the system achieves better compression efficiency without introducing significant quantization noise, thus reducing bitrate while maintaining quality.

Inventive Principle:
Principle #35Parameter changes

2Quantity of substance

If conventional audio encoding techniques are used to compress high-quality audio data, then bitrate reduction is achieved, but computational resources are excessively consumed

Engineering Contradiction:
ImprovebitrateVSAvoidcomputational resources
Core Design Contradiction:
Quantity of substanceVSUse of energy by moving object

Solution Approach 1:

The encoder implements dynamic mode switching between direct Huffman encoding and run-level encoding based on real-time analysis of audio data characteristics. This adaptability allows the system to use computationally intensive methods only when necessary, while relying on simpler encoding strategies for suitable data patterns, thereby reducing overall computational resource consumption while achieving bitrate reduction.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The audio data is processed in segments or blocks, with different encoding strategies applied to different portions based on their characteristics. By dividing the audio stream and applying appropriate encoding methods to each segment, the system avoids uniformly applying complex algorithms to all data, thus reducing total computational overhead while maintaining compression effectiveness.

Inventive Principle:
Principle #1Segmentation

3Device complexity

If direct Huffman encoding is used for all audio coefficients, then encoding simplicity is maintained, but compression efficiency deteriorates for sequences with many zero values

Engineering Contradiction:
Improveencoding complexityVSAvoidcompression efficiency
Core Design Contradiction:
Device complexityVSQuantity of substance

Solution Approach 1:

The encoder dynamically selects between direct Huffman encoding and run-level encoding based on the proportion of zero values in the audio coefficients. When zero values dominate, run-level encoding is activated to achieve better compression. This dynamic adaptation allows the system to maintain simplicity for suitable cases while achieving high compression efficiency when needed, resolving the trade-off between encoding complexity and compression performance.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

Different encoding strategies are applied to different portions of the audio data based on local characteristics. Rather than using a single encoding method for all coefficients, the system applies run-level encoding specifically to regions with many consecutive zeros, while using direct Huffman encoding for other regions. This localized approach optimizes compression efficiency without unnecessarily complicating the encoding of all data.

Inventive Principle:
Principle #3Local quality

4Quantity of substance

If run-level encoding is used for all audio coefficients, then compression efficiency improves for sequences with many zero values, but encoding complexity increases and performance deteriorates for sequences with few zero values

Engineering Contradiction:
Improvecompression efficiencyVSAvoidencoding complexity
Core Design Contradiction:
Quantity of substanceVSDevice complexity

Solution Approach 1:

The encoder implements dynamic mode switching that adapts to the characteristics of the audio data. When the data contains many zero values, run-level encoding is activated to achieve high compression efficiency. When zero values are scarce, the system switches to simpler direct Huffman encoding. This dynamic adaptation allows the system to optimize compression efficiency only when beneficial, avoiding unnecessary complexity for data patterns where run-level encoding would not provide significant advantages.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentUS7433824B2Entropy coding by adapting coding between level and run-length/level modes
Publication Date: 2008.10.07 MICROSOFT TECHNOLOGY LICENSING LLC
  • US7433824B2 patent drawing
  • US7433824B2 patent drawing
  • US7433824B2 patent drawing

AI summary

An audio encoder performs adaptive entropy encoding of audio data. For example, an audio encoder switches between variable dimension vector Huffman coding of direct levels of quantized audio data and run-level coding of run lengths and levels of quantized audio data. The encoder can use, for example, context-based arithmetic coding for coding run lengths and levels. The encoder can determine when to switch between coding modes by counting consecutive coefficients having a predominant value (e.g., zero). An audio decoder performs corresponding adaptive entropy decoding.