QMF Audio Codec Resampling via Configurable Filter Bank Channels
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Solution Overview
Problem
Current audio processing technologies face challenges in efficiently handling different sampling rates, particularly at low bit rates, which require additional computational resources and are not compatible with low-cost hardware, limiting audio bandwidth and increasing complexity.
Innovation Solution
The proposed solution involves a configurable audio signal processor with analysis and synthesis filter banks, controlled by a controller to adjust the number of channels and sampling rates, allowing for flexible sampling rate conversion by modifying the frequency domain representation and reducing the complexity of filter banks through transform length adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If additional resampling functional modules are used to adapt the output sampling rate, then the sampling rate compatibility is improved, but the computational resources required increase significantly
Solution Approach 1:
The patent merges the resampling functionality with the existing QMF filter bank structure by making the analysis and synthesis filter banks configurable with variable numbers of channels. This integration eliminates the need for separate resampling modules, reducing computational overhead while maintaining sampling rate adaptability.
Solution Approach 2:
The filter bank structure is made dynamic and configurable, allowing the number of analysis and synthesis filter bank channels to be adjusted based on the desired sampling rate. This dynamic configuration enables the system to adapt to different sampling rates without requiring fixed, complex resampling hardware for each possible rate.
2Measurement precision
If the number of analysis and synthesis filter bank channels is increased to achieve accurate resampling, then the resampling precision is improved, but the device complexity increases
Solution Approach 1:
The patent changes the parameters of the filter bank structure by allowing configurable numbers of analysis and synthesis filter bank channels. By adjusting these parameters based on the specific resampling requirements, the system achieves the necessary precision without permanently maintaining high complexity across all operating conditions.
3Speed
If conventional resampling technology is used, then the sampling rate conversion is achieved, but the audio bandwidth is limited to the Nyquist frequency which is below the human audible range
Solution Approach 1:
The patent operates in the frequency domain using QMF filter banks, transforming the resampling problem from the time domain to the frequency domain. This dimensional change allows for more flexible manipulation of the audio spectrum, enabling bandwidth extension beyond the traditional Nyquist limit through spectral replication and other frequency domain techniques.
Data Source
AI summary
An apparatus for processing an audio signal includes a configurable first audio signal processor for processing the audio signal in accordance with different configuration settings to obtain a processed audio signal, wherein the apparatus is adapted so that different configuration settings result in different sampling rates of the processed audio signal. The apparatus furthermore includes n analysis filter bank having a first number of analysis filter bank channels, a synthesis filter bank having a second number of synthesis filter bank channels, a second audio processor being adapted to receive and process an audio signal having a predetermined sampling rate, and a controller for controlling the first number of analysis filter bank channels or the second number of synthesis filter bank channels in accordance with a configuration setting.