Spatial Audio Parameter Encoding for Multi-Direction Bitrate Control
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Solution Overview
Problem
Existing spatial audio encoding methods face challenges in optimizing the compression of directional metadata at varying bit rates, particularly at lower bitrates, leading to reduced accuracy in spatial direction quantization when multiple concurrent directions are present.
Innovation Solution
The proposed method modifies energy ratios by determining a quantization spatial resolution based on modified energy ratios, using codebooks with varying resolutions for different direct-to-total energy ratios, and adjusting quantization based on diffuse-to-total energy ratios to optimize accuracy and bit usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If directional metadata is compressed to achieve lower bit rates, then bit rate efficiency is improved, but spatial direction quantization accuracy deteriorates
Solution Approach 1:
The patent applies local quality by differentiating the quantization resolution based on the energy ratio characteristics of different spatial directions. Directions with higher direct-to-total energy ratios receive higher quantization resolution (more accurate spatial direction encoding), while directions with lower energy ratios receive coarser quantization. This local differentiation maintains measurement precision for important directions while improving overall bit rate efficiency.
Solution Approach 2:
The patent changes the quantization resolution parameter dynamically based on the energy ratio values. The system determines quantization spatial resolution by analyzing modified energy ratios and adjusts the number of bits allocated for direction parameter encoding accordingly. This parameter adaptation allows the system to optimize between accuracy and bit rate efficiency by allocating more bits to directions that contribute more to the overall sound field.
2Measurement precision
If higher quantization resolution is used for spatial directions, then measurement precision is improved, but bit rate increases
Solution Approach 1:
Instead of applying uniform high quantization resolution to all spatial directions, the system applies local quality by concentrating higher resolution only on directions with significant energy content (higher direct-to-total ratios). This selective approach maintains measurement precision where it matters most while reducing bit rate consumption for directions with minimal energy contribution.
Solution Approach 2:
The patent applies partial action by providing high quantization resolution only to the extent necessary for directions with higher energy ratios, rather than excessively applying it to all directions. This partial application of high precision achieves the necessary measurement accuracy for important spatial components while avoiding unnecessary bit rate consumption.
3Measurement precision
If energy ratios are modified to optimize quantization, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent modifies energy ratio parameters through specific mathematical operations (determining largest direct-to-total ratios, applying additive inverse transformations, and normalizing ratios). These parameter changes enable the system to derive quantization spatial resolution more accurately from the energy ratio data, improving measurement precision while keeping the complexity manageable through systematic transformation rules.
Data Source
AI summary
An apparatus comprising means configured to: obtain at least one direction parameter value for a time-frequency part of at least one audio signal; obtain at least one energy ratio for the time-frequency part, wherein each energy ratio is associated with a respective direction parameter value; generate respective at least one modified energy ratio from the at least one energy ratio for the time-frequency part; determine a quantization spatial resolution for encoding the at least one obtained direction parameter value based on the at least one modified energy ratio; and encode the obtained direction parameter values based on the quantization spatial resolution.