Audio Decoder Using Inter-Channel Prediction Gain
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Solution Overview
Problem
In audio signal decoding, especially in limited bandwidth scenarios, there is a challenge in reducing the difference between output signals generated at a second device and the original audio signals received at a first device, particularly due to temporal shifts and phase mismatches between audio channels.
Innovation Solution
A decoder system that aligns and encodes audio signals using inter-channel prediction gain parameters, dynamically adjusting bit allocation based on temporal mismatch and energy differences between channels to minimize the difference between synthesized and original signals, thereby improving coding efficiency and reducing bandwidth requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If audio signals are transmitted with full bandwidth and detail, then the quality of output signals matches the original signals, but the communication bandwidth requirement increases
Solution Approach 1:
The patent extracts only the essential parameters needed for signal reconstruction (inter-channel time difference, inter-channel level difference, and mid signal) while discarding redundant information. This allows high-quality reproduction at the receiving end using significantly less bandwidth compared to transmitting the complete original signals.
Solution Approach 2:
The patent transforms the audio signals from their original form into a parameter-based representation. Instead of transmitting full audio waveforms, the system encodes key parameters (ITD, ILD, mid signal) that define the spatial and spectral characteristics, enabling efficient bandwidth utilization while maintaining signal fidelity.
2Quantity of substance
If simple encoding methods are used to reduce bandwidth, then the bandwidth consumption decreases, but the difference between output signals and original signals increases
Solution Approach 1:
The patent performs preliminary processing at the transmitting end by calculating and encoding the inter-channel time difference, inter-channel level difference, and mid signal before transmission. This pre-computation ensures that the essential characteristics are captured accurately, enabling high-fidelity reconstruction at the receiver without requiring excessive bandwidth.
Solution Approach 2:
The patent introduces intermediate parameters (ITD, ILD, mid signal) as mediators between the original dual-channel signals and the reconstructed output. These intermediaries carry the critical spatial and spectral information needed for accurate signal reproduction, bridging the gap between compressed transmission and high-quality output.
3Device complexity
If temporal alignment between audio channels is not corrected, then the processing complexity remains low, but the phase mismatch between channels increases
Solution Approach 1:
The patent performs preliminary temporal alignment by calculating the inter-channel time difference and applying appropriate delay corrections before encoding. This pre-alignment ensures that the signals are properly synchronized, eliminating phase mismatch artifacts in the reconstructed audio without adding significant processing complexity at the receiving end.
Data Source
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AI summary
A device includes a receiver and a decoder. The receiver is configured to receive one or more upmix parameters, one or more inter-channel bandwidth extension parameters, one or more inter-channel prediction gain parameters, and an encoded audio signal. The encoded audio signal includes an encoded mid signal. The decoder is configured to generate a synthesized mid signal based on the encoded mid signal. The decoder is also configured to generate a synthesized side signal based on the synthesized mid signal and the one or more inter-channel prediction gain parameters. The decoder is further configured to generate one or more output signals based on the synthesized mid signal, the synthesized side signal, the one or more upmix parameters, and the one or more inter-channel bandwidth extension parameters.