Apparatus and Method for Audio Signal Coding with Temporal Noise Shaping on Subband Signals

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This invention presents a method and apparatus for audio signal encoding and decoding that improves how quantization noise is shaped in the time domain during audio compression. By using temporal noise shaping (TNS) techniques on subband signals (specifically, those derived from the Modified Discrete Cosine Transform - MDCT domain), the system can better control when and how quantization noise appears, reducing unwanted artifacts such as pre-echo. The process involves transforming the audio into subbands, flattening (in encoding) and then reshaping (in decoding) the temporal envelope of the audio within those subbands. This allows for targeted, adaptive noise shaping without the computational overhead or increased delay of traditional methods, promising improved perceptual audio quality at lower bitrates.

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

• Audio codecs for digital music streaming and wireless audio transmission (e.g., Bluetooth headphones, streaming platforms).
• Voice and speech codecs for telecommunication, conferencing systems, and real-time communications.
• Broadcast media encoding (radio, TV, podcasting) to deliver high-quality audio with limited bandwidth.
• Hearing aids or assistive listening devices, where artifact-free, low-delay processing is critical.
• Embedded audio applications in devices like game consoles, automotive infotainment systems, or smart speakers.

BenefitsContent extracted from patent full text and abstract with AI.

• Reduces perceptible pre-echo and other temporal noise artifacts, resulting in clearer audio, especially for transient-rich content like percussive music or speech plosives.
• Achieves better audio quality at lower bitrates, enabling efficient use of bandwidth and storage.
• Enables flexible, adaptive noise shaping per frequency subband and per frame, leading to more accurate perceptual optimization.
• Minimizes additional processing delay and computational complexity, supporting real-time or low-latency applications.
• Compatible with existing MDCT-based codecs (such as AAC, LC3), facilitating integration into current standards and devices.

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Patent Abstract

An apparatus (200) for audio signal decoding according to an embodiment is provided. The apparatus (200) comprises a decoding unit (210) configured for decoding an audio signal encoding to obtain a decoded spectral-domain audio signal and modification information, wherein the decoded spectral-domain audio signal comprises a plurality of spectral coefficients. Moreover, the apparatus (200) comprises a first transform unit (220) configured for transforming the decoded spectral-domain audio signal from a spectral domain to a subband signal domain to obtain a subband-signal-domain-transformed audio signal comprising a plurality of subband signals. Furthermore, the apparatus (200) comprises a subband signal modifier (230) configured for obtaining a modified subband-signal-domain audio signal by modifying, depending on the modification information, one or more subband signals of the plurality of subband signals of the subband-signal-domain-transformed audio signal. Moreover, the apparatus (200) comprises a second transform unit (240) configured for transforming the modified subband-signal-domain audio signal from the subband signal domain to the spectral domain to obtain a reconstructed spectral-domain audio signal.