Harmonicity-dependent controlling of a harmonic filter tool

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This invention describes an improved way to control a harmonic filter tool in audio codecs, such as those used for speech and music compression. Instead of relying only on a measure of harmonicity (i.e., how periodic or tonal the signal is), the control method uses both a harmonicity measure and a measure of the signal's temporal structure (such as transientness or energy variation), and adapts the decision based on pitch information. This dual-measure approach allows the codec to make smarter, situation-dependent decisions about when and how to activate harmonic filters, which can enhance audio quality and coding efficiency while minimizing unwanted artifacts.

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

• Audio and music codecs for low-bitrate streaming or storage (e.g., AAC, MP3, USAC, EVS, Opus) to improve sound quality.
• VoIP telephony systems and speech communication devices, including mobile phones and conferencing applications.
• Audio recording, editing, and mastering software that uses advanced compression to retain quality at low bitrates.
• Streaming services delivering music or spoken content, especially where bandwidth is limited or fluctuates.
• Hearing aids and assistive listening devices that employ real-time audio processing.
• Embedded audio devices and hardware codecs in consumer electronics such as smart speakers, TVs, and radios.
• Professional broadcast and archive systems for efficient high-quality audio transmission and storage.

BenefitsContent extracted from patent full text and abstract with AI.

• Improves subjective audio quality by better preserving the naturalness of tonal sounds and voiced speech, especially at lower bitrates.
• Reduces or eliminates annoying audio artifacts (such as 'warbling') that are common with previous filtering methods in transform-based codecs.
• Adapts dynamically to both steady, harmonic and rapidly changing (transient) audio content for optimal coding efficiency.
• Prevents the introduction of distortion or artifacts during challenging audio segments, such as mixed transient and harmonic content.
• Enables more efficient use of bandwidth or storage by permitting more aggressive compression without a loss in perceived quality.
• Is computationally efficient and can be implemented in both software and hardware, with suitable optimization for different application needs.
• Enables smarter switching or adjustment of codec blocks (e.g., transform length or prediction methods) based on real-time signal analysis.

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Patent Abstract

The coding efficiency of an audio codec using a controllable - switchable or even adjustable - harmonic filter tool is improved by performing the harmonicity-dependent controlling of this tool using a temporal structure measure in addition to a measure of harmonicity in order to control the harmonic filter tool. In particular, the temporal structure of the audio signal is evaluated in a manner which depends on the pitch. This enables to achieve a situation-adapted control of the harmonic filter tool so that in situations where a control made solely based on the measure of harmonicity would decide against or reduce the usage of this tool, although using the harmonic filter tool would, in that situation, increase the coding efficiency, the harmonic filter tool is applied, while in other situations where the harmonic filter tool may be inefficient or even destructive, the control reduces the appliance of the harmonic filter tool appropriately.