Audio Bit Allocation for Low-Frequency Sub-Band Encoding
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Solution Overview
Problem
Existing frequency domain encoding algorithms face poor signal encoding and decoding performance due to inadequate bit allocation in low frequency sub-bands, which fails to meet their bit requirements effectively.
Innovation Solution
A signal processing method and device that selects low frequency sub-bands, modifies their envelope values based on energy and spectral attributes, and performs bit allocation according to these modified values and original envelope values of other sub-bands to better meet the bit requirements of each sub-band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bit allocation is performed directly according to frequency envelope size of each sub-band, then the encoding process is simple, but the signal encoding and decoding performance is poor due to insufficient bits for low frequency sub-bands
Solution Approach 1:
The patent applies local quality by differentiating bit allocation strategies for different frequency regions. Low frequency sub-bands (first frequency region) receive enhanced bit allocation based on their higher importance to signal quality, while high frequency sub-bands (second frequency region) use standard allocation. This localized differentiation improves overall encoding performance without requiring complete redesign of the entire bit allocation system.
Solution Approach 2:
The patent modifies the bit allocation parameter by introducing a scaling factor that adjusts the number of bits allocated to low frequency sub-bands. Instead of using the raw frequency envelope values directly, the system applies parameter transformation (multiplication by scaling factor > 1) to emphasize low frequency allocation, thereby improving signal quality while maintaining a relatively simple allocation framework.
2Reliability
If more bits are allocated to low frequency sub-bands to improve encoding quality, then signal encoding performance improves, but the overall bit allocation becomes less efficient
Solution Approach 1:
The patent introduces a scaling factor as a可调 parameter to control the degree of bit reallocation to low frequency regions. By adjusting this parameter, the system can optimize the balance between improving low frequency quality and maintaining overall bit efficiency, allowing flexible adaptation to different signal types and quality requirements.
Solution Approach 2:
The patent applies partial action by enhancing bit allocation only to the critical low frequency region rather than uniformly increasing bits across all sub-bands. This targeted approach improves encoding quality where it matters most (low frequencies) while avoiding wasteful over-allocation to less critical high frequency regions, thereby maintaining overall bit efficiency.
Data Source
AI summary
A signal processing method and device includes obtaining spectral coefficients of a current frame of an audio signal, in which N sub-bands of the current frame comprises at least one of the spectral coefficients. A total energy of M successive sub-bands of the N sub-bands, a total energy of K successive sub-bands of the N sub-bands, and an energy of a first sub-band are obtained to determine whether to modify original envelope values of the M sub-bands. When the original envelope values of the M sub-bands are modified, encoding bits are allocated to each of the N sub-bands according to the modified envelope values of the M sub-bands.