Adaptive High Frequency Audio Encoding Using Low Band Signals
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing audio encoding methods prioritize low frequency signals over high frequency signals, leading to suboptimal quality of high frequency sounds when bit allocation is limited, as high frequency signals are often encoded with fewer bits, resulting in reduced sound recognition quality for humans.
Innovation Solution
The method involves adaptively encoding and decoding high frequency signals above a preset frequency band using a signal or spectrum from a low frequency band, either in the time or frequency domain, through domain conversion, noise information encoding, and envelope information extraction, to maximize sound quality with limited bits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high frequency signals are coded by allocating a small number of bits to improve coding efficiency, then bit allocation efficiency is improved, but sound quality recognition is degraded
Solution Approach 1:
The patent uses low frequency band signals as an intermediary to generate high frequency band signals through spectral transformation. Instead of directly encoding high frequency signals with limited bits, the system encodes low frequency signals and transforms them to reconstruct high frequency content, thereby preserving sound quality while maintaining coding efficiency.
Solution Approach 2:
The patent changes the frequency domain parameters by transforming low frequency band signals into high frequency band signals through spectral shifting and transformation techniques. This allows the system to represent high frequency content using fewer bits by leveraging the correlation between low and high frequency bands.
2Manufacturing precision
If low frequency signals are coded by allocating a great number of bits to improve sound quality, then sound quality is improved, but bit allocation efficiency is degraded
Solution Approach 1:
The patent merges the encoding of low frequency and high frequency bands into a unified process. By encoding low frequency signals and transforming them to generate high frequency content, the system combines the benefits of low frequency quality encoding with efficient high frequency representation, avoiding redundant bit allocation.
Solution Approach 2:
The low frequency band encoding process serves multiple functions: it encodes low frequency content directly and simultaneously provides the basis for generating high frequency content through spectral transformation. This multi-functionality improves overall bit allocation efficiency while maintaining sound quality.
3Productivity
If high frequency signals are encoded with fewer bits to maximize coding efficiency, then coding efficiency is improved, but high frequency sound quality is degraded
Solution Approach 1:
The patent performs preliminary encoding of low frequency signals before transforming them to generate high frequency content. This preliminary action ensures that the source material for high frequency reconstruction is of high quality, which compensates for the reduced bit allocation to high frequency bands and maintains overall high frequency sound quality.
Solution Approach 2:
The patent creates a copy or transformation of low frequency band signals to represent high frequency band content. Instead of directly encoding high frequency signals with limited bits, the system copies the essential characteristics from low frequency signals and transforms them to reconstruct high frequency content, preserving quality while improving efficiency.
Data Source
AI summary
Provided are a method and apparatus for encoding and decoding an audio signal. According to the present application, a signal of a high frequency band above a preset frequency band is adaptively encoded or decoded in the time domain or in the frequency domain by using a signal of a low frequency band below the preset frequency band. As such, the sound quality of a high frequency signal is not deteriorate even when an audio signal is encoded or decoded by using a small number of bits and thus coding efficiency may be maximized.