Dynamic Signal Normalization for Low-Level Audio Precision
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Solution Overview
Problem
Low-level digital audio signals experience significant loss in precision due to the discarding of least significant bits during processing, leading to potential saturation and reduced accuracy in representation.
Innovation Solution
Implementing dynamic normalization techniques, specifically using a signal normalizer that adjusts the low band excitation signal based on a calculated normalization factor to prevent saturation and maintain precision, while also adjusting filter states to ensure accurate filtering operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fixed-point arithmetic is used for digital signal processing, then processing speed and efficiency are improved, but precision loss occurs for low-level signals due to discarding least significant bits
Solution Approach 1:
The patent implements dynamic normalization by calculating a normalization factor for each signal frame based on the signal's dynamic range, then applying this factor to scale the signal before processing. This dynamic adjustment allows the system to maintain precision for low-level signals while using fixed-point arithmetic, resolving the contradiction between processing speed and precision.
Solution Approach 2:
The patent changes the parameter of signal amplitude by normalizing the signal to a specific dynamic range before processing. The normalization factor is calculated based on the signal's maximum absolute value and applied to scale the signal, ensuring that low-level signals are boosted to an optimal range for fixed-point processing without losing precision.
2Measurement precision
If normalization factor is increased to prevent saturation, then signal representation accuracy is improved, but precision loss increases due to discarding least significant bits
Solution Approach 1:
The patent applies partial normalization by calculating a normalization factor that is sufficient to prevent saturation but not excessively large. The factor is derived from the signal's actual dynamic range, ensuring that only the necessary scaling is applied to maintain precision while avoiding unnecessary discarding of least significant bits.
Solution Approach 2:
The patent uses feedback from the signal's dynamic range characteristics to adjust the normalization factor. The normalization factor is calculated based on the signal's maximum absolute value and feedback loop ensures that the normalized signal remains within the optimal range for fixed-point processing, balancing saturation prevention with precision maintenance.
3Measurement precision
If dynamic normalization is applied to maintain precision, then signal accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent performs preliminary action by calculating the normalization factor before the main signal processing. The factor is computed once per frame based on the signal's dynamic range, and then applied consistently throughout the processing operations. This preliminary normalization ensures precision is maintained without adding complexity to the core processing algorithms.
Solution Approach 2:
The patent makes the normalization factor serve multiple functions: it prevents saturation, maintains precision for low-level signals, and enables accurate filtering operations. By calculating this single factor based on the signal's maximum absolute value, the system achieves multiple objectives without proportionally increasing computational complexity.
Data Source
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AI summary
A normalization factor for a current frame of a signal may be determined. The normalization factor may depend on an amplitude of the current frame of the signal. The normalization factor may also depend on values of states after one or more operations were performed on a previous frame of a normalized signal. The current frame of the signal may be normalized based on the normalization factor that is determined. The states' normalization factor may be adjusted based on the normalization factor that is determined.