Audio signal decoder, audio signal encoder, method for decoding an audio signal, method for encoding an audio signal and computer program using a pitch-dependent adaptation of a coding context

US9524726B2 · kind B2 · utility

Assignees

• Fraunhofer-Gesellschaft zur förderung der angewandten Forschung e.V. · DE
• Dolby International AB · IE

Inventors

• Stefan Bayer · Nuremberg, DE
• Tom Baeckstroem · Nuremberg, DE
• Ralf Geiger · Erlangen, DE
• Bernd Edler · Hannover, DE
• Sascha Disch · Bad Mergentheim, DE
• Lars Villemoes · Stockholm, SE

Key dates

• Filing date: Sep 10, 2012
• Grant date: Dec 20, 2016
• Expiry date: Feb 16, 2035

Classification

• Technology area (CPC G): Physics
• CPC primary: G10L25/90
• WIPO field: Computer technology
• WIPO sector: Electrical engineering

Abstract

An audio signal decoder includes a context-based spectral value decoder configured to decode a codeword describing one or more spectral values or at least a portion of a number representation thereof in dependence on a context state. The audio signal decoder also includes a context state determinator configured to determine a current context state in dependence on one or more previously decoded spectral values and a time warping frequency-domain-to-time-domain converter configured to provide a time-warped time-domain representation of a given audio frame on the basis of a set of decoded spectral values provided by the context-based spectral value decoder and in dependence on the time warp information. The context-state determinator is configured to adapt the determination of the context state to a change of a fundamental frequency between subsequent audio frames. An audio signal encoder applies a comparable concept.