Audio Decoder, Audio Encoder and Method for Coding of Frames Using a Quantization Noise Shaping

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This patent describes a new technique for audio encoding and decoding that improves the quality of low-bitrate audio compression. The core idea is to use different noise shaping methods for parts of the audio signal that have been quantized to zero (i.e., contain no information after compression) versus those that retain non-zero values. By tailoring the noise shaping functions—using linear prediction coefficients—to be smoother or less smooth depending on the region, the method better preserves perceptual audio quality while maintaining efficient compression. This approach can be utilized in both encoders and decoders as well as in the overall method for audio signal reconstruction.

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

• Digital music streaming services aiming for higher audio quality at low bitrates (e.g. mobile streaming).
• Voice-over-IP (VoIP) and telecommunications systems where bandwidth is limited but speech quality is important.
• Multimedia applications like video conferencing or online gaming that require efficient audio coding.
• Archival and transmission of audio content where storage or network capacity is limited.
• Hearing aids or mobile devices where decoding resources and power consumption are constrained.
• Broadcasting (TV, radio) and digital media distribution services.

BenefitsContent extracted from patent full text and abstract with AI.

• Improved audio quality at low bitrates compared to conventional codecs, especially in spectral and temporal gaps.
• Reduces artifacts such as smearing or loss of detail that often result from highly compressed audio.
• Better preservation of the original signal’s perceptual envelope, leading to more natural-sounding reconstructed audio.
• Flexible implementation—can be incorporated into existing codec frameworks with spectral or temporal noise shaping.
• Adaptable in both hardware and software, suitable for a wide range of devices and use-cases.
• Enables more efficient use of bandwidth or storage without significant loss in perceived audio quality.

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Patent Abstract

Embodiments according to the invention comprise an audio decoder configured to, for a predetermined frame among consecutive frames, decode, from a data stream, a quantized spectrum and a linear prediction coefficient based envelope representation.Furthermore, the decoder is configured to locate, in the quantized spectrum, zero-quantized portions and non-zero-quantized portions and to derive a dequantized spectrum using in zero-quantized portions of the quantized spectrum, filling the quantized spectrum with a synthesized spectral data modified depending, according to a first manner, on the linear prediction coefficient based envelope representation, and in non-zero-quantized portions of the quantized spectrum, modifying the quantized spectrum depending, in a second manner, on the linear prediction coefficient based envelope representation.In addition, the decoder is configured to reconstruct the predetermined frame using the dequantized spectrum. The audio decoder is configured so that, for a predetermined portion, the modification according to the first manner and the modification according to the second manner cause a spectral quantization noise shaping which comprises different smoothness characteristics.Beyond that, corresponding encoders and methods are disclosed.