Parametric Audio Encoder Spatial Parameter Post-Processing
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Solution Overview
Problem
Existing multi-channel audio encoders do not employ efficient methods for encoding, resulting in high bit rates due to the large number of channels, and the stereo-to-multi-channel upmix process loses spatial information, which affects the quality of the down-mix.
Innovation Solution
A method and device that process stereo signals using spatial parameters obtained from an N-channel encoder to apply parameter-dependent post-processing, enhancing the spatial impression and quality of the down-mix while maintaining the possibility of multi-channel decoding without influencing the upmix process, by controlling filtering effects with time and frequency-dependent parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If individual channel encoding is applied to multi-channel audio, then encoding simplicity is maintained, but bit rate increases due to the large number of channels
Solution Approach 1:
The patent combines multiple audio channels into a reduced set of channels (e.g., front, rear, center) and applies joint encoding techniques. By merging channel information and using parametric representation, the system reduces the total bit rate while maintaining encoding simplicity through unified processing of combined channel data.
2Adaptability or versatility
If stereo-to-multi-channel upmix process is applied, then multi-channel reconstruction is enabled, but spatial information is lost in the down-mix process
Solution Approach 1:
The patent applies preliminary processing to the stereo down-mix signal by using the transmitted spatial parameters to control post-processing algorithms before multi-channel reconstruction. This preliminary action enhances the down-mix quality and preserves spatial characteristics by pre-adjusting the stereo signal based on the original spatial parameters, ensuring better reconstruction quality.
3Manufacturing precision
If parameter-dependent post-processing is applied to enhance down-mix quality, then perceptual quality improves, but processing complexity increases
Solution Approach 1:
The patent uses transmitted spatial parameters to dynamically control post-processing algorithms, adjusting filtering and enhancement operations based on the actual spatial characteristics of the original multi-channel signal. By changing processing parameters adaptively rather than applying fixed complex processing, the system improves down-mix quality while keeping processing complexity manageable through parameter-driven control.
Data Source
AI summary
Method for processing a stereo signal includes encoding an N-channel audio signal in a stereo signal (Lo, Ro) and spatial parameters (wl, wr), processing the stereo signal using the spatial parameters for generating a processed stereo signal (low, Row). The matrix of the processed stereo signal is described as the matrix of the stereo signal, multiplied by a filter matrix (H) having element that are filter functions (H1, H2, H3, H4) operated with spatial parameters (wl, wr) and a constant (a). The filter functions are time invariant and selected so that the matrix is invertible.