Patent ID: 11942101
Assignee: FRAUNHOFER GESELLSCHAFT ZUR FÖRDERUNG DER ANGEWANDTEN FORSCHUNG E.V.
Field: Basic communication processes (Electrical engineering)
Classification: CPC G  H | IPC G  H

Claim 5:
6. An audio decoding apparatus for decoding an encoded audio stream representing a sampled audio signal to acquire a sequence of segments of coefficients being subsequent to each other in time and representing the sampled audio signal by using different transform lengths such that segments of coefficients for which different transform lengths are used, spectrally represent the sampled audio signal at different frequency resolutions, comprising
a processor configured to derive a coding context for a currently decoded coefficient of a current segment based on a previously decoded coefficient of a previous segment, the previous and current segments corresponding to different frequency resolutions and different transform lengths, respectively; and
an entropy decoder configured to entropy decode, using arithmetic decoding, the current coefficient based on the coding context and the encoded audio stream,
wherein the processor is adapted for deriving the coding context per spectral band for the current coefficient, based on neighbouring spectral coefficients previously decoded in the previous segment and in the present segment,
wherein the entropy decoder is adapted for decoding a group index from the encoded audio stream based on a probability distribution derived from the coding context, wherein the group index represents a group of one or more codewords, and for, based on a uniform probability distribution, decoding an element index from the encoded audio stream if the group index indicates a group comprising more than one codeword, and for deriving a tuple of spectral coefficients of the current segment based on the group index and the element index, thereby acquiring the spectral domain representation in tuples of spectral coefficients.