Spatial Audio Direction Quantization for Multi-Source Bit Reduction
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Solution Overview
Problem
Existing spatial audio encoding technologies face challenges in efficiently compressing spatial audio parameters, particularly when multiple sound sources are present in a time-frequency tile, leading to high bit rates and inefficiencies in bit allocation for spatial metadata transmission.
Innovation Solution
Transforming the spatial audio direction parameters associated with each sound source to point in the same direction, specifically by rotating one direction by 180 degrees relative to the other, and quantizing the difference between these parameters, conditional on energy ratio or bit availability thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If spatial audio direction parameters for multiple sound sources are encoded separately, then spatial accuracy is improved, but bit rate increases
Solution Approach 1:
The patent merges the encoding of multiple spatial audio direction parameters by transforming them into a common reference frame. Instead of encoding each direction parameter independently, the method combines multiple sound source directions into a unified representation using transformation matrices, thereby reducing the total bit rate while preserving spatial accuracy for all sound sources.
Solution Approach 2:
The patent changes the parameter representation by transforming direction parameters from individual sound source references to a common reference frame. This parameter transformation allows the system to encode spatial relationships more efficiently by exploiting correlations between multiple sound sources, reducing redundancy in the encoded data.
2Productivity
If spatial metadata is compressed to reduce bit rate, then transmission efficiency is improved, but spatial resolution deteriorates
Solution Approach 1:
The patent applies preliminary transformation actions to the spatial metadata before compression. By pre-transforming the direction parameters into a common reference frame and establishing hierarchical relationships between parameters, the system prepares the data structure to withstand compression while maintaining spatial resolution. This preliminary structuring allows efficient compression without sacrificing critical spatial information.
3Measurement precision
If multiple direction parameters are quantized with high precision, then spatial accuracy is improved, but encoding complexity increases
Solution Approach 1:
The patent segments the encoding process into distinct stages: transformation to common reference frame, hierarchical parameter organization, and selective quantization. This segmentation allows the system to apply different precision levels to different parameter groups based on their importance, reducing overall encoding complexity while maintaining high spatial accuracy for critical parameters.
Data Source
AI summary
There is inter alia disclosed an apparatus for spatial audio encoding configured to: determine, for two or more audio signals, a first spatial audio direction parameter and a second spatial audio direction parameter for providing spatial audio reproduction: quantize the first spatial audio direction parameter (301); transform the second spatial audio direction parameter to have an opposite spatial audio direction (303); determine a difference between the transformed second spatial audio direction parameter and the quantized first spatial audio direction parameter (305); and quantize the difference (307).