Abstract: Methods of estimating frequency skew in a packet network include determining a representation of a packet delay variation (PDV) sequence from an initial estimate of frequency skew between master and slave devices in the packet network and timestamps transmitted therebetween. An operation is performed to extract a statistical mode from an empirical probability distribution function (PDF) of the representation of the PDV sequence, where the statistical mode corresponds to a value at which the PDF has its maximum value. The, an updated estimate of the frequency skew is generated by determining a slope between timestamps at indices associated with a plurality of points in the representation of the PDV sequence that are within a range of the statistical mode.

Abstract: Methods of performing time-of-day synchronization in a packet processing network include accumulating timestamps transmitted in packets between master and slave devices, which are synchronized to respective master and slave clocks and separated from each other by the packet processing network. Operations are also performed to determine whether first timestamps accumulated in a first direction across the packet network demonstrate that a first packet delay variation (PDV) sequence observed from the first timestamps is stationary. A phase offset between the master and slave clocks is then adjusted using a time-of-day (ToD) estimation algorithm. This adjusting can include evaluating a location-dependent statistic of the first PDV sequence.

Abstract: Methods of packet-based synchronization in non-stationary network environments can include accumulating timestamps transmitted in packets between master and slave devices that are separated from each other by a packet network. Operations are also performed to determine whether first timestamps accumulated in a first direction across the packet network demonstrate that a first packet delay variation (PDV) sequence observed from the first timestamps is stationary. Thereafter, estimates of at least one of frequency skew and phase offset between the master and slave clocks are acquired using a first algorithm, from the first timestamps accumulated in the first direction. These operations of determining further include determining whether second timestamps accumulated in a second direction demonstrate that a second packet delay variation (PDV) sequence observed from the second timestamps is stationary.

Abstract: The invention relates to compressing of sparse data sets contains sequences of data values and position information therefor. The position information may be in the form of position indices defining active positions of the data values in a sparse vector of length N. The position information is encoded into the data values by adjusting one or more of the data values within a pre-defined tolerance range, so that a pre-defined mapping function of the data values and their positions is close to a target value. In one embodiment, the mapping function is defined using a sub-set of N filler values which elements are used to fill empty positions in the input sparse data vector. At the decoder, the correct data positions are identified by searching though possible sub-sets of filler values.

Abstract: A method is disclosed for maintaining spatial queues in digital sound signals. Sound signals are received from each of a plurality of transducers. The sound signals are transformed using a common real-valued spectral gain, G, to maintain spatial cues within the sound signals, the common spectral gain, G, determined by: calculating G as a function of a derivative of a known cost function and as a function of at least one multichannel frequency-domain Bayesian short-time estimator.

Abstract: The invention relates to a method and apparatus for efficient encoding of media signals including audio. A 2d sparse representation, or spikegram, of one frame of a digitized audio signal is generated using an overcomplete set of kernels. The spikegram is then mapped to a non-negative matrix, which is decomposed into a 3D component matrix containing hidden components and a 3D weight matrix using a two-dimensional non-negative matrix factorization. Elements of the 3D component and weight matrices are then adaptively quantized using integer programming to determine an optimal quantization scheme, and the quantized values are the optionally encoded using an arithmetic coder.

Abstract: The invention relates to compressing of sparse data sets contains sequences of data values and position information therefor. The position information may be in the form of position indices defining active positions of the data values in a sparse vector of length N. The position information is encoded into the data values by adjusting one or more of the data values within a pre-defined tolerance range, so that a pre-defined mapping function of the data values and their positions is close to a target value. In one embodiment, the mapping function is defined using a sub-set of N filler values which elements are used to fill empty positions in the input sparse data vector. At the decoder, the correct data positions are identified by searching though possible sub-sets of filler values.

Abstract: The invention relates to sparse parallel signal coding using a neural network which parameters are adaptively determined in dependence on a pre-determined signal shaping characteristic. A signal is provides to a neural network encoder implementing a locally competitive algorithm for sparsely representing the signal. A plurality of interconnected nodes receive projections of the input signal, and each node generates an output once an internal potential thereof exceeds a node-dependent threshold value. The node-dependent threshold value for each of the nodes is set based upon the pre-determined shaping characteristic. In one embodiment, the invention enables to incorporate perceptual auditory masking in the sparse parallel coding of audio signals.