Audio Decoder Frequency Domain Sub-band Processing

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Solution Overview

Problem

Existing MP3 decoders require high-capacity memory and high-performance processors due to their complex operations, and are not compatible with multi-channel codecs that process bitstreams in the transform domain.

Innovation Solution

A decoding apparatus and method that splits decoded bitstreams into sub-band signals and transforms them in the frequency domain, using synthesis filter bank coefficients to generate synthesis audio signals, reducing operational complexity and enabling compatibility with multi-channel codecs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If MP3 decoder uses complicated operations such as convolution to synthesize restored bitstream, then sound quality is improved, but device complexity and processing requirements increase significantly

Engineering Contradiction:

Improvesound qualityVSAvoiddecoder complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces time-domain convolution operations with frequency-domain multiplication operations. By transforming the synthesis process from time domain to frequency domain using FFT, the complex convolution operation is substituted with simpler multiplication in the frequency domain, reducing computational complexity while maintaining sound quality.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the domain parameter from time domain to frequency domain. By performing synthesis operations in the frequency domain rather than time domain, the computational complexity is reduced from O(N²) convolution to O(N log N) FFT-based multiplication, while preserving audio quality.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If MP3 decoder processes restored bitstream in time domain, then decoding is straightforward, but compatibility with multi-channel codecs is lost

Engineering Contradiction:

Improvedecoding simplicityVSAvoidcodec compatibility

Core Design Contradiction:

Ease of operationVSAdaptability or versatility

Solution Approach 1:

The patent makes the decoder universal by implementing frequency-domain processing capability. By using FFT-based synthesis that operates in the frequency domain, the decoder can handle both stereo MP3 bitstreams and multi-channel AC3 bitstreams, providing multi-functionality and broad codec compatibility.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If MP3 decoder uses frequency domain transformation, then compatibility with multi-channel codecs is improved, but operational complexity increases

Engineering Contradiction:

Improvemulti-channel codec compatibilityVSAvoidprocessing complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent substitutes complex time-domain convolution with simpler frequency-domain multiplication. Although FFT transformation is introduced, the overall complexity is reduced because frequency-domain multiplication is computationally less intensive than time-domain convolution, especially for multi-channel synthesis.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Productivity

If MP3 decoder requires large-capacity memory and high-performance processor, then high-speed operation is achieved, but cost and hardware requirements increase

Engineering Contradiction:

Improvedecoding speedVSAvoidhardware requirements

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent replaces computationally intensive time-domain convolution with frequency-domain multiplication using FFT. This substitution reduces the computational load and memory requirements, enabling high-speed decoding with lower-performance processors and smaller memory capacity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach decreases operational complexity, increases decoding speed without the need for large memory or high-performance processors, and allows compatibility with multi-channel codecs by processing bitstreams in the frequency domain, thereby enhancing sound quality.

Implementation Method 1

generating n transformed sub-band signals by transforming the n sub-band signals in a frequency domain; The n transformed sub-band signals may be generated by fast Fourier transforming the n sub-band signals

Methodology Applied

Scientific EffectFast Fourier Transform:

Data Source

PatentUS8762158B2Decoding method and decoding apparatus therefor

Publication Date: 2014.06.24 SAMSUNG ELECTRONICS CO LTD

AI summary

A method and apparatus for generating synthesis audio signals are provided. The method includes decoding a bitstream; splitting the decoded bitstream into n sub-band signals; generating n transformed sub-band signals by transforming the n sub-band signals in a frequency domain; and generating synthesis audio signals by respectively multiplying the n transformed sub-band signals by values corresponding to synthesis filter bank coefficients.