Spatial Audio Parameter Encoding with Penalty-Based Bit Allocation
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Solution Overview
Problem
Current audio encoding technologies face challenges in efficiently encoding directional components of spatial audio metadata, particularly in quantizing elevation and azimuth parameters across time-frequency subbands, which affects the accuracy and bitrate management of spatial audio signals.
Innovation Solution
The proposed solution involves determining penalty values for each subband based on bit allocation differences and subjective perceptibility errors, ordering subbands by penalty values, and dynamically redistributing bits between subbands for optimal encoding of directional and energy ratio parameters using quantization or entropy encoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If uniform bit allocation is used for encoding directional values across all sub-bands, then encoding complexity is reduced, but encoding accuracy and perceptual quality deteriorate
Solution Approach 1:
The patent applies local quality by allocating different bit rates to different sub-bands based on their specific characteristics. The bit allocation is determined by calculating penalty values for each sub-band that reflect the perceptual impact of quantization errors, allowing important sub-bands to receive more bits while less critical sub-bands receive fewer bits, thereby optimizing overall encoding accuracy without uniformly increasing complexity
Solution Approach 2:
The patent changes the bit allocation parameter dynamically based on the audio signal characteristics. By computing penalty values that depend on the directional energy ratios and perceptual importance of each sub-band, the system adapts the encoding precision locally, transforming the fixed uniform bit allocation into a variable allocation scheme that responds to signal content
2Measurement precision
If more bits are allocated to encode directional values in all sub-bands, then encoding accuracy is improved, but overall bitrate increases
Solution Approach 1:
The patent applies local quality by concentrating bit allocation resources on sub-bands that have high penalty values, indicating greater perceptual importance or higher sensitivity to quantization errors. Less important sub-bands receive fewer bits, ensuring that the total bitrate remains constrained while encoding accuracy is improved where it matters most
Solution Approach 2:
The patent applies partial action by selectively applying high-precision encoding only to the necessary sub-bands rather than uniformly across all sub-bands. The penalty value calculation identifies which sub-bands require enhanced encoding accuracy, allowing the system to apply excessive precision only where needed rather than everywhere
3Productivity
If penalty value calculation and bit redistribution is implemented, then encoding efficiency is improved, but computational complexity increases
Solution Approach 1:
The patent applies preliminary action by calculating penalty values for all sub-bands before the actual bit allocation and encoding process. This pre-computation of penalty values based on directional energy ratios and perceptual models allows the system to plan the optimal bit distribution in advance, making the subsequent encoding process more efficient despite the initial computational investment
Solution Approach 2:
The patent applies self-service by using the penalty value calculation to automatically determine the optimal bit allocation without requiring manual intervention or complex iterative optimization. The system serves itself by using the computed penalty values to directly guide the bit redistribution and encoding process
Data Source
AI summary
An apparatus comprising means for: obtaining values for parameters representing an audio signal, the values comprising at least one directional value and at least one energy ratio value for each sub-band of at least two sub-bands of a frame of the audio signal; determining a penalty value for each sub-band; and on a sub-band by sub-band basis: selecting a sub-band based on the penalty value; and encoding, for the selected sub-band, the at least one directional value for each sub-band; distributing any bits allocated for encoding the selected sub-band at least one directional value which are not used in the encoding of the at least one directional value to succeeding selections of sub-bands.