Directional Audio Coding Parameters With Split Time-Frequency Resolution
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Solution Overview
Problem
Current spatial audio coding techniques, such as Directional Audio Coding (DirAC), face challenges in achieving low bit-rate transmission of 3D audio scenes due to high data requirements, particularly in scenarios beyond teleconference applications, where the capability of DirAC is reduced and assumptions limit the communication to wideband speech, leading to insufficient bit-rate reduction.
Innovation Solution
The proposed solution involves encoding directional audio coding parameters by providing diffuseness and direction parameters with different resolutions, using different quantization and encoding methods, such as grouping and averaging, weighted averaging, and entropy coding, to reduce the bit-rate while maintaining quality, allowing for efficient coding of spatial audio metadata.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If DirAC technique is used to represent spatial sound parametrically, then the amount of data to transmit is reduced, but the spatial resolution and quality of audio reproduction deteriorate due to limited bit-rate
Solution Approach 1:
The audio signal is segmented into multiple frequency bands using a filter bank, allowing independent processing of spatial parameters for each band. This segmentation enables efficient allocation of bit-rate resources across different frequency ranges, maintaining spatial resolution where most perceptually relevant while reducing data amount in less critical bands.
Solution Approach 2:
Different time and frequency resolutions are applied to different spatial parameters locally. Direction parameters use higher time resolution for precise localization, while diffuseness parameters use lower time resolution. This local differentiation optimizes the balance between data reduction and spatial quality preservation in specific regions of the parameter space.
2Measurement precision
If uniform high resolution is used for both direction and diffuseness parameters, then spatial quality is maintained, but the bit-rate increases significantly
Solution Approach 1:
The invention changes the resolution parameters of different spatial attributes differently. Direction parameters are encoded with high time resolution to preserve localization accuracy, while diffuseness parameters use lower time resolution. Frequency resolution is also varied by band, matching perceptual importance. This differential parameter allocation maintains spatial quality where needed while significantly reducing overall bit-rate.
3Quantity of substance
If teleconference assumptions are applied to limit DirAC capability, then bit-rate is reduced, but the applicability to general audio scenarios is lost
Solution Approach 1:
The encoding system dynamically adapts resolution allocation based on the audio scenario and content characteristics. Instead of fixed teleconference optimizations, the system can adjust time and frequency resolution parameters according to the specific application requirements, enabling versatile deployment across immersive audio, music, speech, and other scenarios while maintaining efficient bit-rate usage.
Data Source
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AI summary
An apparatus for encoding directional audio coding parameters comprising diffuseness parameters and direction parameters, comprises: a parameter calculator (100) for calculating the diffuseness parameters with a first time or frequency resolution and for calculating the direction parameters with a second time or frequency resolution; and a quantizer and encoder processor (200) for generating a quantized and encoded representation of the diffuseness parameters and the direction parameters.