Multichannel Audio Coding with Channel and Frequency Extension
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Solution Overview
Problem
Current audio compression techniques struggle to efficiently encode and decode multi-channel audio at high quality while minimizing bitrate, especially in resource-constrained computer systems, leading to suboptimal listening experiences and increased storage and transmission costs.
Innovation Solution
The implementation of channel extension coding and frequency extension coding techniques, which involve encoding a combined channel and determining parameters to represent individual source channels as modified versions, allowing for efficient bitrate reduction and improved audio quality by maintaining cross-channel correlation and power statistics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional audio compression techniques are used, then bitrate is reduced, but audio quality and cross-channel correlation are degraded
Solution Approach 1:
The audio signal is segmented into individual source channels and a combined channel. The encoder separately encodes the combined channel and determines parameters representing individual source channels as modified versions of the combined channel. This segmentation allows efficient bitrate reduction while maintaining the ability to reconstruct high-quality multi-channel audio through parameter-based synthesis of individual channels.
Solution Approach 2:
The patent transitions from encoding only individual channels to encoding in an additional dimension by introducing a combined channel representation. This combined channel serves as a base representation, with individual source channels represented as parameter-based modifications. This dimensional expansion enables more efficient compression while preserving audio quality and cross-channel correlation.
2Use of energy by moving object
If resource-constrained processing is used, then computational load is reduced, but encoding efficiency and audio quality are compromised
Solution Approach 1:
Instead of encoding and transmitting full individual channel data, the patent creates parameter-based representations (copies) of individual source channels derived from the combined channel. These parameter representations require significantly less computational processing and transmission resources while maintaining the ability to reconstruct the original channels with high fidelity, thus improving encoding efficiency under resource constraints.
3Quantity of substance
If individual channels are encoded separately, then channel independence is maintained, but bitrate and storage requirements increase
Solution Approach 1:
The patent merges individual source channels into a combined channel representation for encoding purposes. By encoding the combined channel and using parameter-based modifications to represent individual channels, the system achieves significant bitrate reduction. The merging process preserves channel independence through the parameter representations, allowing flexible reconstruction of individual channels when needed while maintaining efficient compression.
Data Source
AI summary
An audio encoder receives multi-channel audio data comprising a group of plural source channels and performs channel extension coding, which comprises encoding a combined channel for the group and determining plural parameters for representing individual source channels of the group as modified versions of the encoded combined channel. The encoder also performs frequency extension coding. The frequency extension coding can comprise, for example, partitioning frequency bands in the multi-channel audio data into a baseband group and an extended band group, and coding audio coefficients in the extended band group based on audio coefficients in the baseband group. The encoder also can perform other kinds of transforms. An audio decoder performs corresponding decoding and/or additional processing tasks, such as a forward complex transform.