Hybrid Audio Scene Encoding for Accurate Spatial Cues at Low Bit Rates
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Solution Overview
Problem
Existing audio coding methods at medium to low bit rates face challenges in accurately estimating spatial parameters due to the non-wave-form preserving nature of parametric coding tools, leading to misestimation of spatial cues and sub-optimal audio quality.
Innovation Solution
A hybrid encoding/decoding scheme where spatial parameters are estimated and coded in the encoder for some parts of the audio signal and transmitted to the decoder, while others are estimated directly in the decoder, allowing for high-quality parametric information preservation and efficient bit allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If parametric coding tools are used to reduce bit rate, then transmission efficiency is improved, but spatial parameter estimation accuracy deteriorates
Solution Approach 1:
The audio signal is divided into two portions: a first portion coded using wave-form-preserving coding to maintain spatial cues, and a second portion coded using parametric coding to reduce bit rate. This segmentation allows each portion to be optimized for its specific function, resolving the contradiction between bit rate reduction and spatial parameter accuracy.
Solution Approach 2:
Different coding qualities are applied to different portions of the audio signal. The first portion receives high-quality wave-form-preserving coding where spatial accuracy is critical, while the second portion receives lower-quality parametric coding where bit rate efficiency is prioritized. This local differentiation allows optimal performance for each region.
2Measurement precision
If spatial parameters are estimated in the decoder, then time-frequency resolution is improved, but device complexity increases
Solution Approach 1:
The system segments spatial parameter estimation between encoder and decoder. The encoder estimates and transmits spatial parameters for the second portion, while the decoder estimates spatial parameters for the first portion. This division reduces the computational burden on the decoder while maintaining high time-frequency resolution.
3Reliability
If wave-form-preserving coding is used, then audio quality is improved, but bit rate consumption increases
Solution Approach 1:
The audio signal is segmented into two portions with different coding strategies. The first portion uses wave-form-preserving coding to maintain audio quality where it matters most, while the second portion uses parametric coding to significantly reduce bit rate consumption. This segmentation makes the overall system efficient in terms of bit rate while maintaining quality.
Solution Approach 2:
High-quality wave-form-preserving coding is applied locally to the first portion of the audio signal where spatial cues are most important, while parametric coding is applied to the second portion where bit rate efficiency is more critical, optimizing the quality-bit rate trade-off.
Data Source
AI summary
An audio scene encoder for encoding an audio scene, the audio scene having at least two component signals, has: a core encoder for core encoding the at least two component signals, wherein the core encoder is configured to generate a first encoded representation for a first portion of the at least two component signals, and to generate a second encoded representation for a second portion of the at least two component signals, a spatial analyzer for analyzing the audio scene to derive one or more spatial parameters or one or more spatial parameter sets for the second portion; and an output interface for forming the encoded audio scene signal, the encoded audio scene signal having the first encoded representation, the second encoded representation, and the one or more spatial parameters or one or more spatial parameter sets for the second portion.