Audio Bandwidth Extension Encoding Using Spectral Copying
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current audio signal encoding methods face limitations in efficiently encoding high-frequency domains due to bit restrictions, necessitating improved methods to enhance encoding efficiency and bandwidth extension.
Innovation Solution
The proposed solution involves an encoding apparatus and method that includes a down-sampling unit, core-encoding unit, frequency transforming unit, and extension encoding unit, which generates a basic signal for the high-frequency domain by copying and folding a low-frequency section, estimating an envelope, and controlling energy using tonality calculations to perform bandwidth extension encoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large number of bits are allocated to low-frequency domain signals, then encoding quality of low-frequency signals is improved, but the available bits for high-frequency domain signals are reduced
Solution Approach 1:
The patent applies copying by generating a basic signal in the high-frequency domain that replicates the spectral characteristics of the low-frequency signal. This basic signal is then modified with envelope information to create the extended high-frequency representation, effectively copying the essential features without requiring direct encoding of all high-frequency components
Solution Approach 2:
The patent introduces envelope information as an intermediary element that bridges the low-frequency and high-frequency domains. The envelope captures the spectral shape information that is transferred from the low-frequency signal to shape the synthesized high-frequency signal, acting as a mediator that conveys essential characteristics between frequency domains
2Productivity
If Spectral Band Replication technology is used to represent high-band components as an envelope, then encoding efficiency is improved, but bandwidth extension capability is limited
Solution Approach 1:
The patent applies parameter changes by modifying the basic signal through envelope multiplication and applying energy control factors. These parameter transformations allow the synthesized high-frequency signal to adapt to different input signal characteristics and achieve extended bandwidth while maintaining encoding efficiency
Solution Approach 2:
The patent introduces dynamic elements through energy control factors that are calculated based on the relationship between the basic signal and the target high-frequency signal. These dynamic parameters allow the system to adaptively adjust the energy distribution in the extended bandwidth, making the bandwidth extension capability flexible and versatile
Data Source
AI summary
An apparatus and method for encoding and decoding a signal for high frequency bandwidth extension are provided. An encoding apparatus may down-sample a time domain input signal, may core-encode the down-sampled time domain input signal, may transform the core-encoded time domain input signal to a frequency domain input signal, and may perform bandwidth extension encoding using a basic signal of the frequency domain input signal.