Spatial Audio Direction Encoding With Opposite-Parameter Quantization
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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.
Innovation Solution
The method involves transforming the direction parameter of one sound source to be opposite to another within a time-frequency tile, reducing the difference and quantizing this transformed parameter, conditional on energy ratio or bit threshold criteria, to enhance quantization efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If spatial audio parameters are encoded using conventional methods for multiple sound sources, then spatial audio reproduction is achieved, but the number of bits required to represent spatial audio parameters increases significantly
Solution Approach 1:
The patent transforms the second direction parameter by adding 180 degrees to create an opposite direction, then encodes the difference between this transformed parameter and the first direction parameter. This parameter transformation reduces the bit representation from encoding two independent direction parameters to encoding one direction parameter and one difference value, thereby reducing the total number of bits while maintaining spatial audio reproduction quality.
2Loss of information
If direction parameters for multiple sound sources are independently quantized, then spatial information is preserved, but encoding efficiency decreases and bit rate increases
Solution Approach 1:
Instead of independently quantizing two direction parameters, the patent inverts the conventional approach by transforming one direction parameter to be opposite and then encoding the difference between the transformed and original parameters. This inversion strategy allows the encoder to exploit the correlation between opposite directions, thereby improving encoding efficiency while preserving spatial information through differential quantization.
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: transform the second spatial audio direction parameter to have an opposite spatial audio direction; determine a difference between the transformed second spatial audio direction parameter and the quantized first spatial audio direction parameter; and quantise the difference.