Thomson Licensing

Dolby Laboratories Licensing Corporation

Other

Dolby International Ab

Xiaoming Chen

Peter Georg Baum

Ulrich Gries

Michael Arnold

Johannes Boehm

Oliver Theis

Sven Kordon

Alexander Krueger

Florian Keiler

Gael Pilard

Meinolf Blawat

Klaus Gaedke

Dietmar Hepper

Holger Kropp

Ingo Huetter

Herbert Hoelzemann

Stefan Abeling

Friedrich Timmermann

For generating 3D audio content from a two-channel stereo signal, the stereo signal (x(t)) is partitioned into overlapping sample blocks and is transformed into time-frequency domain. From the stereo signal directional and ambient signal components are separated, wherein the estimated directions of the directional components are changed by a predetermined factor, wherein, if changes are within a predetermined interval, they are combined in order to form a directional centre channel object signal. For the other directions an encoding to Higher Order Ambisonics HOA is performed. Additional ambient signal channels are generated by de-correlation and rating by gain factors, followed by encoding to HOA. The directional HOA signals and the ambient HOA signals are combined, and the combined HOA signal and the centre channel object signals are transformed to time domain.

Method and apparatus for generating 3D audio content from two-channel stereo content

A system for converting a channel-based 3D audio signal to a higher-order Ambisonics HOA audio signal, the channel-based 3D audio signal is transformed from time domain to frequency domain. A primary ambient decomposition is carried out for three-channel triplets of blocks of the domain channel-based 3D audio signal, wherein directional signals and ambient signals are provided for each triplet. From the directional signals directional information of a total directional signal for each triple is derived. That total directional signal is HOA encoded according to the derived directions, and ambient signals are HOA encoded according to channel positions. The HOA coefficients of the HOA encoded directional signal and the HOA coefficients of the HOA encoded ambient signal are superimposed in order to obtain a HOA coefficients signal for the channel-based 3D audio signal, followed by a transformation into time domain.

Method and apparatus for converting a channel-based 3D audio signal to an HOA audio signal

For generating 3D audio content from a two-channel stereo signal, the stereo signal (x(t)) is partitioned into overlapping sample blocks and is transformed into time-frequency domain. From the stereo signal directional and ambient signal components are separated, wherein the estimated directions of the directional components are changed by a predetermined factor, wherein, if changes are within a predetermined interval, they are combined in order to form a directional center channel object signal. For the other directions an encoding to Higher Order Ambisonics (HOA) is performed. Additional ambient signal channels are generated by de-correlation and rating by gain factors, followed by encoding to HOA. The directional HOA signals and the ambient HOA signals are combined, and the combined HOA signal and the center channel object signals are transformed to time domain.

Currently there is no simple and satisfying way to create 3D audio from existing 2D content. The conversion from 2D to 3D sound should spatially redistribute the sound from existing channels. From a multi-channel 2D audio input signal (x(t)) a 3D sound representation is generated which includes an HOA representation Formula (I) and channel object signals Formula (II) scaled from channels of the 2D audio input signal. Additional signals Formula (III) placed in the 3D space are generated by scaling (; Formula (IV)) channels from the 2D audio input signal and by decorrelating (; Formula (V)) a scaled version of a mix of channels from the 2D audio input signal, whereby spatial positions for the additional signals are predetermined. The additional signals Formula (III) are converted () to a HOA representation Formula (I).

Method and apparatus for generating from a multi-channel 2D audio input signal a 3D sound representation signal

A challenge of audio watermarking systems in which an acoustic path is involved is the robustness against microphone pickup in case of surrounding noise. The strength of phase-based watermarking is increased by determining a masking threshold for a current frequency bin in a frequency/phase representation changing the phase based on that masking threshold and an allowed phase change value, calculating an allowed magnitude change value for the current frequency bin and calculating from an audio quality level value a magnitude change scaling factor for the magnitude change value, and increasing its magnitude accordingly.

Method and apparatus for increasing the strength of phase-based watermarking of an audio signal

A code book is generated for mapping source to target code words which allows encoding source data at reduced probability of incorrect decoding, e.g. for DNA storage. The target code words are grouped () into subsets and comprise identifying and remaining portions. The identifying portions of target code words corresponding to a same subset are identical. A first code symbol set of source code words is selected () for addressing the subsets. For the subsets, neighboring subsets are determined (). The identifying portions of the target code words of neighboring subsets differ from those of the corresponding subset by up to a predetermined amount of symbols. Source code words are assigned () where the corresponding first code symbols address the same subset to said subset such that an amount of target code words of said subset having their remaining portions identical to their neighboring subsets corresponds to an optimization criterion.

Code generation method, code generating apparatus and computer readable storage medium

Following transmission of a watermarked audio signal over an acoustic path causing echoes, reverberation and/or noise, watermark detection correlation result peak values are concentrated within a limited temporal range around main correlation result peaks, which limited temporal range is much smaller than the total correlation length. The watermark detection is based on the following: given ncorrelation result peak values v=(v, v, . . . , v) in an average or expected probability distribution for correlation result values for unmarked content, the probability is calculated that within windows covering the limited temporal range there are nor more values from a correlation result value set greater than or equal to these peaks v.

Method and apparatus for determining watermark symbols in a received audio signal that can contain echoes, reverberation and/or noise

Audio watermarking is the process of embedding watermark information items into an audio signal in an in-audible manner. In a first embodiment, in case the original audio signal has parts of low signal energy, an alternative signal having a level or strength given by the psycho-acoustic model is combined with the original audio signal. The combined signal is watermarked with watermark data to be embedded. In a second embodiment, in case the original audio signal has parts of low signal energy, an alternative signal having a level or strength given by the psycho-acoustic model is watermarked with watermark data to be embedded, and the audio signal is watermarked with the watermark data to be embedded. The watermarked alternative signal is combined with the watermarked audio signal.

Method and apparatus for watermarking successive sections of an audio signal

For watermark embedding, without full Dolby AC-3 decoding, mantissa bits in the AC-3 bit stream are changed by exploiting the fact that during AC-3 encoding more bits than required by the perceptual masking curve are used for the quantization of the MDCT coefficient mantissa values. In addition to the bap values, truly required bap values are determined and the mantissa values are changed accordingly, controlled by the watermark information. The advantages are efficient watermark embedding, other bit stream parameters and values remain unchanged except for CRC checks, and the audio quality of the watermarked signal remains perceptually unchanged.

Method and apparatus for watermarking an AC-3 encoded bit stream

Digital audio signal watermarking in real-time is difficult in an environment that has limited processing power. According to the invention, the channels in a data block-based audio multi-channel signal are prioritized with respect to watermarking importance, whereby the channel priority can change for different input signal data blocks. For a current input signal block, the most important channel is watermarked and the required processing time is determined. If this required processing time is shorter than a predefined application-dependent threshold, the next most important channel is marked and the additionally required processing time is determined, and so on. Due to the block-based nature of the audio watermarking including block overlap/add and due to the sensitivity of the resulting audio quality against blocking artifacts, several problems are solved in order to lead to acceptable performance and quality.

Method and apparatus for frequency domain watermark processing a multi-channel audio signal in real-time

Watermark symbol detection requires a detection metric for deciding at decoder side which candidate symbol is embedded inside the audio or video signal content. The invention provides an improved detection metric processing that achieves a reliable detection of watermarks in the presence of additional noise and echoes, and that is adaptive to signal reception conditions and requires a decreased computational power. This is performed by taking into account the information contained in the echoes of the received audio signal in the decision metric and comparing it with the corresponding metric obtained from decoding a non-marked audio signal, based on recursive calculation of false positive detection rates of peaks in correlation result values. The watermark symbol corresponding to the reference sequence having the lowest false positive error is selected as the embedded one.

Method and apparatus for detecting which one of symbols of watermark data is embedded in a received signal

In accordance with an exemplary embodiment of the present invention, a method for measuring a quality parameter of an optical storage system comprising a non-diffraction-limited optical storage medium and a readout device, the method comprising the process of deriving an impulse response of the optical storage system, and the process of analyzing the impulse response to determine at least one of a width of the impulse response and a skewness of the impulse response as the quality parameter.

Method and system for determining the quality of a storage system

The error correction capability of block codes can be doubled if error locations are known. Prior art approaches for error location detection always involve adding dedicated redundant data which then are evaluated to yield error location information. The present invention proposes and describes how error location information in the form of clues is derived from given DC control bits that are anyway present in a data stream.

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Hannover, Germany

Xiaoming Chen