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

摘要

An audio signal decoder (150 for providing a decoded audio signal representation (154) on the basis of an encoded audio signal representation (152) comprising an encoded spectrum representation (ac_spectral_data[]) and an encoded time warp information (tw_data[]) comprises a context-based spectral value decoder (160) configured to decode a codeword (acod_m) describing one or more spectral values or at least a portion (m) of a number representation of one or more spectral values in dependence on a context state, to obtain decoded spectral values (162, 297, x_ac_dec[]). The audio signal decoder also comprises a context state determinator (170) configured to determine a current context state (164, c) in dependence on one or more previously decoded spectral values (162, 297). The audio signal decoder also comprises a time warping frequency-domain-to-time-domain converter (180) configured to provide a time-warped time-domain representation (182) of a given audio frame on the basis of a set of decoded spectral values (162) associated with the given audio frame and provided by the context-based spectral value decoder and in dependence on the time warp information. The context-state determinator (170) 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.