	US 11,942,101 B2
	Audio entropy encoder/decoder with arithmetic coding and coding context
Markus Multrus, Nuremberg (DE); Bernhard Grill, Lauf (DE); Guillaume Fuchs, Nuremberg (DE); Stefan Geyersberger, Wuerzburg (DE); Nikolaus Rettelbach, Nuremberg (DE); and Virgilio Bacigalupo, Nuremberg (DE)
Assigned to Fraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V., Munich (DE)
Filed by Fraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V., Munich (DE)
Filed on Apr. 14, 2023, as Appl. No. 18/301,194.
Application 18/301,194 is a continuation of application No. 16/888,176, filed on May 29, 2020, granted, now 11,670,310.
Application 16/888,176 is a continuation of application No. 16/283,591, filed on Feb. 22, 2019, granted, now 10,685,659, issued on Jun. 16, 2020.
Application 16/283,591 is a continuation of application No. 14/589,881, filed on Jan. 5, 2015, granted, now 10,242,681, issued on Mar. 26, 2019.
Application 14/589,881 is a continuation of application No. 13/004,282, filed on Jan. 11, 2011, granted, now 8,930,202, issued on Jan. 6, 2015.
Application 13/004,282 is a continuation of application No. PCT/EP2009/003521, filed on May 18, 2009.
Claims priority of provisional application 61/103,820, filed on Oct. 8, 2008.
Claims priority of provisional application 61/079,842, filed on Jul. 11, 2008.
Prior Publication US 2023/0326470 A1, Oct. 12, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. G10L 19/02 (2013.01); G10L 19/022 (2013.01); H03M 7/30 (2006.01)

CPC G10L 19/02 (2013.01) [G10L 19/022 (2013.01); H03M 7/30 (2013.01)]

10 Claims

5. Method for encoding a sequence of segments of coefficients, the segments being subsequent to each other in time, the method comprising providing the sequence of segments of coefficients from an audio stream representing a 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;

deriving, using a computer, a coding context for a currently encoded coefficient of a current segment based on a previously encoded coefficient of a previous segment, the previous and current segments corresponding to different frequency resolutions and different transform lengths, respectively; and

entropy encoding, using the computer, using arithmetic coding, the current coefficient based on the coding context to acquire an encoded audio stream,

wherein the entropy encoding comprises encoding the current coefficient in units of a tuple of spectral coefficients and for predicting a range of the tuple based on the coding context, and

wherein the entropy encoding comprises dividing the tuple by a predetermined factor as often as necessitated to fit a result of the division in a predetermined range and for encoding a number of divisions necessitated, a division remainder and the result of the division when the tuple does not lie in the predicted range, and encoding the tuple without the use of any division when the tuple already lies within the predicted range.

10. A method 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

deriving, using a computer, 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

entropy decoding, using the computer, using arithmetic decoding, the current coefficient based on the coding context and the encoded audio stream,

wherein the deriving comprises 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 decoding comprises 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, 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 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.