Multi-Channel Audio Encoding with Dynamic Rate Control
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Solution Overview
Problem
Current multi-channel audio codec systems face challenges in efficiently encoding and decoding multi-channel audio signals, particularly in maintaining downward compatibility and optimizing data-rate allocation between independent and dependent substreams to ensure high audio quality.
Innovation Solution
A frame-based audio encoder configured to encode multi-channel audio signals according to the Dolby Digital Plus standard, using a basic and extension group of channels, with a rate control unit that adapts data-rates based on momentary coding quality indicators to optimize the sum of independent and dependent substream data-rates, ensuring efficient encoding and decoding across different channel configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multi-channel audio signals are encoded into multiple substreams (independent and dependent) for downward compatibility, then compatibility with legacy decoders is improved, but the complexity of encoding and decoding increases
Solution Approach 1:
The patent divides the multi-channel audio signal into multiple substreams (independent substream and dependent substreams), where each substream can be independently decoded by legacy decoders. This segmentation allows N.1 decoders to process only the independent substream while M.1 decoders can access both substreams for full functionality, thus achieving downward compatibility without requiring complex modifications to legacy decoders.
Solution Approach 2:
The independent substream is designed to serve multiple purposes: it can be decoded by both legacy N.1 decoders and modern M.1 decoders. The dependent substream provides additional functionality for M.1 decoders. This multi-functionality approach allows a single encoded bitstream to support multiple decoder types and channel configurations, reducing the need for separate encoding systems.
2Ease of manufacture
If fixed data-rates are allocated to independent and dependent substreams, then encoding simplicity is maintained, but audio quality optimization is limited
Solution Approach 1:
The patent implements dynamic data-rate allocation where the data-rates for independent and dependent substreams are adjusted frame-by-frame based on the coding difficulty of each frame. The rate control unit monitors coding quality indicators and redistributes available data-rate dynamically, allowing the system to optimize audio quality for each frame while maintaining overall bit-rate constraints, thus resolving the trade-off between encoding simplicity and audio quality.
Solution Approach 2:
The patent employs a feedback mechanism where coding quality indicators from previous frames are used to adjust data-rate allocation for subsequent frames. The rate control unit receives feedback on coding difficulty and quality metrics, then dynamically modifies the data-rates allocated to different substreams to optimize overall audio quality while maintaining encoding simplicity through automated control.
3Manufacturing precision
If data-rates are dynamically adjusted based on coding quality indicators, then audio quality is improved, but the complexity of rate control increases
Solution Approach 1:
The rate control unit automatically adjusts data-rates based on coding quality indicators without requiring manual intervention or complex external control systems. The system monitors its own coding performance and self-regulates the data-rate allocation to optimize audio quality, thus improving precision while keeping the control mechanism relatively simple through autonomous operation.
Data Source
AI summary
The present document relates to audio encoding/decoding. In particular, the present document relates to a method and system for improving the quality of encoded multi-channel audio signals. An audio encoder configured to encode a multi-channel audio signal according to a total available data-rate is described. The multi-channel audio signal is representable as a basic group (121) of channels for rendering the multi-channel audio signal in accordance to a basic channel configuration, and as an extension group (122) of channels, which—in combination with the basic group (122)—is for rendering the multi-channel audio signal in accordance to an extended channel configuration. The basic channel configuration and the extended channel configuration are different from one another.