Parametric Multi-Channel Audio Encoding with Spatial Metadata
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Solution Overview
Problem
Current parametric multi-channel audio coding systems face challenges in bandwidth efficiency, computational efficiency, and robustness, particularly in generating high-quality multi-channel audio signals at low data-rates.
Innovation Solution
An audio encoding system that generates a bitstream containing a downmix signal and spatial metadata, using a Dolby Digital Plus encoder, to enable the decoding system to produce a multi-channel upmix signal. This system includes a downmix processing unit, a parameter processing unit to determine spatial metadata, and a configuration unit to manage control settings for data-rate and quality, allowing for efficient encoding and decoding of multi-channel audio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If parametric multi-channel audio coding is used to provide increased listening quality at low data-rates, then audio quality is improved, but bandwidth efficiency and computational efficiency deteriorate
Solution Approach 1:
The audio signal is segmented into multiple frequency bands, with different coding strategies applied to each band. High-frequency bands use parametric coding while low-frequency bands use full-band coding, optimizing the trade-off between quality and bandwidth efficiency for different spectral regions
Solution Approach 2:
The system changes coding parameters dynamically based on signal characteristics. Spatial parameters such as inter-channel correlation and phase difference are extracted and transmitted instead of full audio data, reducing bandwidth requirements while maintaining perceptual quality
2Measurement precision
If parametric multi-channel audio coding is used to provide increased listening quality at low data-rates, then audio quality is improved, but computational efficiency deteriorates
Solution Approach 1:
Instead of performing full spatial analysis on all frequency bands, the system applies parametric coding only where beneficial (high-frequency bands), performing partial analysis that reduces computational load while maintaining quality where it matters most
Solution Approach 2:
The system extracts and transmits simplified spatial parameters (inter-channel correlation, phase difference) rather than full spatial impulse responses, reducing both encoding and decoding computational complexity while preserving essential spatial information
3Reliability
If spatial metadata is encoded and transmitted to enable multi-channel upmixing, then robustness in audio reproduction is improved, but bitstream data-rate increases
Solution Approach 1:
The system extracts only the essential spatial parameters needed for robust reproduction (inter-channel correlation and phase difference) and transmits them separately from the audio data, isolating the metadata that provides robustness while minimizing its impact on overall bitstream size
Data Source
AI summary
The present document relates to audio coding systems. In particular, the present document relates to efficient methods and systems for parametric multi-channel audio coding. An audio encoding system configured to generate a bitstream indicative of a downmix signal and spatial metadata for generating a multi-channel upmix signal from the downmix signal is described. The system comprises a downmix processing unit configured to generate the downmix signal from a multi-channel input signal; wherein the downmix signal comprises m channels and wherein the multi-channel input signal comprises n channels; n, m being integers with m<n. Furthermore, the system comprises a parameter processing unit configured to determine the spatial metadata from the multi-channel input signal. In addition, the system comprises a configuration unit configured to determine one or more control settings for the parameter processing unit based on one or more external settings; wherein the one or more external settings comprise a target data-rate for the bitstream and wherein the one or more control settings comprise a maximum data-rate for the spatial metadata.