Bit Allocation for Spatial Audio Parameters by Sub-band
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Solution Overview
Problem
Existing multichannel audio coding techniques face challenges in efficiently allocating bit budgets for spatial information parameters, often relying on uniform quantization without considering auditory perception, leading to suboptimal spatial resolution and increased quantization errors.
Innovation Solution
A method that estimates spatial resolution in each frequency sub-band based on energy and spectral properties, dynamically allocating bits to prioritize sub-bands most relevant to auditory perception, minimizing quantization errors by adapting bit allocation according to the sensitivity of the auditory system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If uniform quantization is used for spatial information parameters across all sub-bands, then the encoding process is simple and consistent, but the spatial resolution is suboptimal and quantization errors increase
Solution Approach 1:
The patent applies local quality by allocating different bit depths to different frequency sub-bands based on their individual characteristics. Specifically, sub-bands with higher energy or greater auditory importance receive more bits for quantization, while less important sub-bands receive fewer bits. This non-uniform allocation optimizes spatial resolution where it matters most while managing overall bit budget constraints.
Solution Approach 2:
The bit allocation scheme is dynamic rather than static. The encoder determines the number of bits to allocate to each sub-band based on the actual energy distribution and spectral characteristics of the audio signal in each time frame. This allows the system to adapt to changing spatial and spectral conditions, optimizing quantization precision dynamically.
2Loss of information
If more bits are allocated to each sub-band, then quantization errors are reduced, but the overall bit budget is exceeded and transmission efficiency decreases
Solution Approach 1:
The patent changes the parameter of bit allocation from a fixed uniform value to a variable value determined by sub-band energy and auditory importance. By computing the energy of each sub-band and applying psychoacoustic weighting, the system dynamically adjusts the number of bits allocated to each sub-band, ensuring that quantization error is minimized where it impacts perception most while maintaining overall bit budget compliance.
Solution Approach 2:
Rather than uniformly distributing bits across all sub-bands, the system applies partial action by concentrating bits only on sub-bands that contribute most to spatial perception. Sub-bands with low energy or low auditory importance receive minimal or zero additional bits, while critical sub-bands receive enhanced allocation, achieving better perceptual quality with the same total bit rate.
3Measurement precision
If bit allocation is based on energy properties of sub-bands, then spatial resolution is optimized for auditory perception, but the encoding complexity increases due to additional calculations
Solution Approach 1:
The patent performs preliminary action by calculating the energy of each frequency sub-band before the quantization process. This pre-computed energy information is then used to determine the optimal bit allocation for each sub-band. By preparing this information in advance, the system avoids more complex real-time optimizations during encoding while still achieving perceptually optimal results.
Data Source
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AI summary
The present invention relates to a method for allocating bits for quantifying spatial information parameters by frequency sub-band for the parametric encoding/decoding of a multichannel audio stream representative of a soundstage consisting of a plurality of sound sources. Said method comprises a step of quantifying or inversely quantifying, by frequency sub-band, spatial information parameters for the sound sources of the soundscape. The method is characterized in that it comprises the following steps: assessing (E203) a spatial resolution of the current sub-band on the basis of the spectral properties of the sub-band; and determining (E204) a number of bits to be allocated to the current sub-band, the number of bits to be allocated being inversely proportional to the estimated spatial resolution. The invention also relates to a device for allocating quantification bits implementing the above-described method.