Phase Coherence Control for Harmonic Signals in Perceptual Audio Codecs

Simple SummaryContent extracted from patent full text and abstract with AI.

This invention relates to a method and apparatus for improving the sound quality of perceptual audio codecs by controlling the phase coherence (specifically, vertical phase coherence, or VPC) of harmonic signals during the encoding and decoding processes. The system analyzes audio signals to determine their phase coherence, encodes control information, and then uses this information upon decoding to adjust the phase of the audio, thereby reducing unwanted artifacts and preserving the natural sound quality, especially for tonal and harmonic audio such as speech or musical instruments.

Use CasesContent extracted from patent full text and abstract with AI.

• Audio codecs for music streaming services to enhance the quality of compressed audio.
• Speech codecs in telecommunication to make voices sound more natural.
• Audio restoration or enhancement in digital archiving and media remastering.
• Professional music production and post-processing to maintain the integrity of instrumental sounds after coding or effects processing.
• Consumer electronics like smartphones, TVs, or portable music players using perceptual coding.
• Digital effects like pitch shifting or time-stretching without introducing unnatural 'phasiness'.
• Hearing aids or assistive listening devices for clearer sound reproduction.

BenefitsContent extracted from patent full text and abstract with AI.

• Significantly improves audio quality at low bitrates by preserving important phase relationships.
• Reduces common digital audio artifacts like dullness, 'phasiness', or loss of clarity in harmonic content.
• Maintains the perceptual authenticity of tonal instruments and voiced speech.
• Allows time- and frequency-selective phase correction, optimizing audio quality only where it's most needed, hence being bandwidth efficient.
• Compatible with existing perceptual audio codecs – can be implemented as an add-on feature.
• Low computational and data overhead due to compact side information.
• Enhances listener engagement by delivering more natural, engaging, and spatially accurate audio.

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Patent Abstract

A decoder for decoding an encoded audio signal to obtain a phase-adjusted audio signal is provided. The decoder comprises a decoding unit (1 10) and a phase adjustment unit (120). The decoding unit (110) is adapted to decode the encoded audio signal to obtain a decoded audio signal. The phase adjustment unit (120) is adapted to adjust the decoded audio signal to obtain the phase-adjusted audio signal. The phase adjustment unit (120) is configured to receive control information depending on a vertical phase coherence of the encoded audio signal. Moreover, the phase adjustment unit (120) is adapted to adjust the decoded audio signal based on the control information.