Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V.

Dolby International Ab

Daniel Homm

Ralph Sperschneider

Martin Dietz

Reinhold Böhm

Reinhold Boehm

Heiko Purnhagen

Juergen Herre

Michael Schug

Holger Hoerich

Martin Wolters

Karsten Linzmeier

Thomas Ziegler

Tobias Friedrich

Alexander Groeschel

Wolfgang Alexander Schildbach

Tobias R Wagenblass

Claus-Christian Spenger

Pierre Lauber

Oliver Watzke

Wolfgang A Schildbach

A decoding system reconstructs an audio signal based on an input signal representing the audio signal by parametric coding or by n discretely coded channels. Parametric decoding proceeds on the basis of a core signal and mixing parameters controlling a spatial synthesis stage, which is supplied with a downmix signal. A controller is responsible for controlling the components of the decoding system, whether in steady-state parametric mode, steady-state discrete decoding mode and transitions between these. In defective frames of the input signal, which do not allow the mixing parameters to be decoded, the controller is configured to perform various error handling procedures including: parametric decoding using previous values of the mixing parameters; continuing parametric decoding for a limited duration, and/or outputting the core signal without spatial synthesis.

Error concealment strategy in a decoding system

The present document relates to techniques for authentication of data streams. Specifically, the present document relates to the insertion of identifiers into a data stream, such as a Dolby Pulse, AAC or HE AAC bitstream, and the authentication and verification of the data stream based on such identifiers. A method and system for encoding a data stream comprising a plurality of data frames is described. The method comprises the step of generating a cryptographic value of a number N of successive data frames and configuration information, wherein the configuration information comprises information for rendering the data stream. The method then inserts the cryptographic value into the data stream subsequent to the N successive data frames.

Authentication of data streams

An entropy encoder includes an apparatus for producing a data stream which comprises two reference points, of code words of variable lengths, the apparatus comprising a first device for writing at least a part of a code word into the data stream in a first direction of writing, starting from a first reference point, and a second device for writing at least a part of a code word into the data stream in a second direction of writing, which is opposite to the first direction of writing, starting from the other reference point. In particular, when a raster having a plurality of segments is used to write the code words of variable lengths into the data stream, the number of the code words which can be written starting at raster points is doubled, in the best case, such that the data stream of code words of variable lengths is robust toward a propagation of sequence errors.

Apparatus and method for producing a data stream and apparatus and method for reading a data stream

A device for concealing an error in an erroneous or potentially erroneous information unit generates output values of a forward decoder and a backward decoder which differ and thus indicate an error-concealment area. The different values for one and the same information unit are examined with regard to a predetermined criterion so as to select that value which meets the predetermined criterion, i.e. which is plausible. Thus, an elimination or reduction of the continuation errors introduced in the decoding of blocks of reversible code words of variable lengths is achieved without impacting the compression rate.

Device and method for concealing an error

In a method for concealing an error in an encoded audio signal a set of spectral coefficients is subdivided into at least two sub-bands (), whereupon the sub-bands are subjected to a re-verse transform (). A specific prediction is performed () for each quasi time signal of a sub-band to obtain an estimated temporal representation for a sub-band of a set of spectral coefficients following the current set. A forward transform () of the time signal of each sub-band provides estimated spectral coefficients which can be used () instead of erroneous spectral coefficients of a following set of spectral coefficients, e.g. in order to conceal transmission errors. Transforming at the sub-band level provides independence from transform characteristics such as block length, window type and MDCT algorithm while at the same time preserving spectral processing for error concealment. Thus the spectral characteristics of audio signals can also be taken into account during error concealment.

Method and device for error concealment in an encoded audio-signal and method and device for decoding an encoded audio signal

Growing community of inventors

Erlangen, Germany

Daniel Homm