Multi-Channel Audio Envelope Shaping for Transient Spatial Quality
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Solution Overview
Problem
Current multi-channel audio coding technologies face challenges in accurately reproducing the spatial distribution of signals with high temporal granularity, particularly for transient signals like applause, leading to poor transient reproduction and unnatural sound perception.
Innovation Solution
The proposed solution involves a decoder and encoder system that uses a waveform parameter representation with intermediate time resolution to shape upmixed channels, allowing for finer temporal control of the signal envelope without increasing the bit rate significantly, by deriving a low-resolution representation of the channel and calculating waveform parameters with a time resolution higher than the frame repetition rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If frame-based parametric coding is used to reduce bit rate, then data transmission efficiency is improved, but temporal resolution of signal envelope is degraded
Solution Approach 1:
The patent segments the temporal resolution into multiple levels: frame-based parametric coding for overall structure, and intermediate-resolution waveform parameters for transient details. This multi-scale segmentation allows efficient bit rate usage while preserving important temporal information.
Solution Approach 2:
The patent introduces an intermediate time resolution dimension between the frame repetition rate and the full sampling rate. This intermediate dimension provides sufficient temporal detail for transient signals without requiring full high-resolution data transmission.
2Manufacturing precision
If high time resolution waveform parameters are transmitted to accurately shape upmixed channels, then spatial sound quality is improved, but bit rate increases
Solution Approach 1:
The patent applies different quality levels to different signal characteristics: intermediate-resolution waveform parameters are used specifically for shaping transient signals and signal envelopes, while full high-resolution parameters are not transmitted. This local quality approach optimizes the balance between sound quality and bit rate.
3Manufacturing precision
If decorrelated signal time envelope is shaped to match downmix channel, then transient reproduction is improved, but complexity of temporal shaping increases
Solution Approach 1:
The patent changes the parameter resolution from full high-resolution to intermediate resolution for waveform parameters. This parameter change reduces the computational complexity of temporal shaping operations while maintaining sufficient accuracy for transient signal reproduction.
Data Source
AI summary
A selected channel of a multi-channel signal which is represented by frames composed from sampling values having a high time resolution can be encoded with higher quality when a wave form parameter representation representing a wave form of an intermediate resolution representation of the selected channel is derived, the wave form parameter representation including a sequence of intermediate wave form parameters having a time resolution lower than the high time resolution of the sampling values and higher than a time resolution defined by a frame repetition rate. The wave form parameter representation with the intermediate resolution can be used to shape a reconstructed channel to retrieve a channel having a signal envelope close to that one of the selected original channel. The time scale on which the shaping is performed is shorter than the time scale of a framewise processing, thus enhancing the quality of the reconstructed channel. On the other hand, the shaping time scale is larger than the time scale of the sampling values, significantly reducing the amount of data needed by the wave form parameter representation.