Stereo Audio Encoding Phase Alignment Parameter Reduction
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Solution Overview
Problem
Existing methods for encoding and decoding stereo audio are inefficient in compressing and encoding the necessary parameters, leading to suboptimal compression ratios.
Innovation Solution
The method involves generating a phase-adjusted second channel audio to match the phase of the first channel audio, creating mono-audio by adding both channels, and encoding based on this mono-audio and phase differences, reducing the number of parameters needed for encoding and decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional parametric audio coding is used to encode stereo audio by downmixing to mono and encoding multiple parameters (IID, ICC, OPD, IPD), then the audio can be compressed, but the number of parameters increases the encoding complexity and reduces compression efficiency
Solution Approach 1:
The patent extracts and eliminates redundant parameters from the traditional set. By adjusting the phase of the second channel audio to match the first channel audio in the frequency band, the invention removes the need to encode separate phase difference parameters (OPD and IPD), retaining only the intensity-related parameters (IID and ICC) for compression.
Solution Approach 2:
The patent merges the phase adjustment operation with the downmixing process. By adjusting the phase of the second channel to match the first channel before adding them together, the invention combines multiple parameter adjustments into a single phase alignment operation, simplifying the overall encoding process.
2Reliability
If multiple parameters (IID, ICC, OPD, IPD) are encoded to restore stereo audio from mono audio, then the audio restoration can be achieved, but the encoding and decoding process becomes more complex
Solution Approach 1:
The patent removes the phase difference parameters (OPD and IPD) from the encoding process by pre-adjusting the phase of the second channel audio to match the first channel audio. This extraction of redundant phase information simplifies the encoding process while maintaining audio restoration quality through the remaining intensity parameters.
3Device complexity
If the phase of the second channel audio is adjusted to match the first channel audio before downmixing, then the number of parameters needed for encoding is reduced, but an additional phase adjustment operation is required
Solution Approach 1:
The patent performs the phase adjustment of the second channel audio as a preliminary action before the downmixing operation. By pre-aligning the phases in the frequency domain, the invention prepares the audio signals in advance to eliminate redundant parameters during encoding, though it adds an initial processing step.
Data Source
AI summary
Provided are a method and apparatus for encoding/decoding stereo audio. In the method for encoding stereo audio, stereo audio is encoded based on at least one of the phase difference between first and second channel audios and information on an angle made by a vector on the intensity of mono-audio and a vector on the intensity of the first channel audio or a vector on the intensity of the second channel audio. Thus, the number of encoded parameters is minimized so that a compression ratio in the encoding of the stereo audio is improved.