High-Frequency Bandwidth Extension Using Folded SBR Basic Signals
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Solution Overview
Problem
Current audio signal encoding methods face limitations in efficiently encoding high-frequency domains due to bit allocation restrictions, necessitating improved methods for bandwidth extension in Spectral Band Replication (SBR) technology to enhance encoding efficiency.
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 encoding efficiency for high-frequency signals deteriorates due to bit allocation restrictions
Solution Approach 1:
The patent applies copying by generating a basic signal that replicates the spectral characteristics of the low-frequency domain signal and folding it to create the high-frequency domain signal. This copying approach allows the high-frequency signal to be synthesized from the low-frequency signal properties, enabling efficient bandwidth extension without requiring separate high-quality encoding for high-frequency components, thus resolving the bit allocation contradiction.
2Productivity
If Spectral Band Replication technology is used to represent high-band component signals as an envelope, then encoding efficiency is improved, but bandwidth extension capability is limited
Solution Approach 1:
The patent extends SBR technology by introducing a folding operation that transforms the spectral representation from a single-band envelope to a multi-band folded structure. This dimensional transformation allows the basic signal to be replicated across multiple frequency bands through folding, thereby enhancing bandwidth extension capability while preserving the encoding efficiency benefits of envelope-based representation.
3Adaptability or versatility
If bandwidth extension encoding is performed using basic signal generation, then high-frequency domain bandwidth is extended, but encoding complexity increases
Solution Approach 1:
The patent segments the bandwidth extension process into distinct functional modules: basic signal generation, folding operation, and energy control. This segmentation allows each component to be optimized independently and processed in a systematic manner, reducing overall encoding complexity while maintaining comprehensive bandwidth extension capability across multiple frequency bands.
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.