Apparatus and method for efficient synthesis of sinusoids and sweeps by employing spectral patterns

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

This patent discloses a method and apparatus for efficiently generating and reconstructing musical tones, such as sinusoids and frequency sweeps, in digital audio codecs—especially at low bit rates. Instead of directly coding natural tones that are hard to compress without artifacts, the invention locates prominent tonal components in the audio spectrum and replaces them with precomputed or adaptively generated 'spectral patterns' that can accurately synthesize pure tones or sweeps during decoding. These patterns are blended into the spectrum in a computationally lightweight way, enabling high perceived audio quality (especially for music with tonal content) even when data rates are severely constrained.

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

• Improving the perceptual audio quality of music and speech codecs at low bit rates, such as in streaming services and telecommunication applications.
• Enhancing compression efficiency for digital audio broadcasting (e.g., DAB, internet radio).
• Reducing artifacts like 'warbling' in transform-based audio codecs (AAC, USAC, etc.) when transmitting tonal music at low data rates.
• Implementing high-quality, low-latency audio transmission for real-time communication, gaming, and conferencing systems.
• Deploying efficient audio decoders on resource-constrained hardware, such as mobile devices or embedded systems.
• Archiving and streaming musical content where storage or bandwidth is limited but tonal fidelity is essential.

BenefitsContent extracted from patent full text and abstract with AI.

• Significantly reduces annoying coding artifacts (e.g., warbling, roughness) in low bit rate audio codecs for music with strong tonal components.
• Allows seamless integration with existing transform-based audio codecs (like AAC, USAC) without demanding major changes to encoder/decoder pipelines.
• Greatly decreases computational complexity compared to traditional time-domain methods—enabling use in low-power or real-time systems.
• Maintains high perceptual quality despite aggressive compression and low bit rates, especially important for music.
• Reduces the need for transmitting detailed sinusoidal parameters, as only sparse 'pseudo coefficients' and pattern indices are signaled, lowering side information overhead.
• Provides scalable quality: as bit rate increases, the approach can gracefully fall back to standard transform coding without abrupt quality changes.

Technical Classifications (CPCs)

Inventors & Applicants

Patent Abstract

An apparatus for generating an audio output signal based on an encoded audio signal spectrum is provided. The apparatus comprises a processing unit (115) for processing the encoded audio signal spectrum to obtain a decoded audio signal spectrum comprising a plurality of spectral coefficients, wherein each of the spectral coefficients has a spectral location within the encoded audio signal spectrum and a spectral value, wherein the spectral coefficients are sequentially ordered according to their spectral location within the encoded audio signal spectrum so that the spectral coefficients form a sequence of spectral coefficients. Moreover, the apparatus comprises a pseudo coefficients determiner (125) for determining one or more pseudo coefficients of the decoded audio signal spectrum, each of the pseudo coefficients having a spectral value. Furthermore, the apparatus comprises a replacement unit (135) for replacing at least one or more pseudo coefficients by a determined spectral pattern to obtain a modified audio signal spectrum, wherein the determined spectral pattern comprises at least two pattern coefficients, wherein each of the at least two pattern coefficients has a spectral value. Moreover, the apparatus comprises a spectrum-time-conversion unit (145) for converting the modified audio signal spectrum to a time-domain to obtain the audio output signal.