Audio Decoder Spatial Upmix via Selective Decorrelator Control
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Solution Overview
Problem
Existing audio signal processing methods for format conversion, such as downmixing and upmixing, suffer from high complexity and potential artifacts due to unnecessary processing steps, and lack flexibility in adapting to different playback setups.
Innovation Solution
An audio decoder device with a core decoder and format converter, utilizing decorrelators and mixers, allows independent control of decorrelators based on the target loudspeaker setup to generate incoherent output channels, reducing computational complexity and artifacts by selectively applying decorrelation only where necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If decorrelator processing is applied to all channels in format conversion, then spatial coherence and audio quality are improved, but computational complexity increases
Solution Approach 1:
The patent applies decorrelator processing selectively only to specific channels that require spatial separation, rather than uniformly to all channels. The format converter analyzes the target loudspeaker setup and applies decorrelation only where necessary to create incoherent channels, leaving other channels processed differently. This localized application maintains audio quality where needed while reducing overall computational complexity.
2Ease of manufacture
If format conversion uses fixed processing methods, then decoding simplicity is maintained, but adaptability to different playback setups is reduced
Solution Approach 1:
The patent implements dynamic adaptability by allowing the format converter to adjust its processing based on the target loudspeaker setup. The system can switch between different processing modes (applying decorrelation to some channels, not others) depending on the playback configuration. This dynamic behavior enables the same decoder to adapt to various playback scenarios while maintaining relatively simple decoding operations.
3Reliability
If unnecessary decorrelation processing is applied, then channel incoherence is improved, but audio artifacts increase
Solution Approach 1:
The patent extracts and removes the decorrelator processing from channels that do not require spatial separation. By selectively excluding certain channels from decorrelation processing, the system avoids introducing audio artifacts in those channels while still achieving sufficient incoherence in channels where spatial separation is necessary for the target loudspeaker configuration.
Data Source
AI summary
An audio decoder device for decoding a compressed input audio signal having at least one core decoder having one or more processors for generating a processor output signal based on a processor input signal, wherein a number of output channels of the processor output signal is higher than a number of input channels of the processor input signal, wherein each of the one or more processors has a decorrelator and a mixer, wherein a core decoder output signal having a plurality of channels has the processor output signal, and wherein the core decoder output signal is suitable for a reference loudspeaker setup; at least one format converter device configured to convert the core decoder output signal into an output audio signal, which is suitable for a target loudspeaker setup; and a control device configured to control at least one or more processors in such way that the decorrelator of the processor may be controlled independently from the mixer of the processor, wherein the control device is configured to control at least one of the decorrelators of the one or more processors depending on the target loudspeaker setup.