Skype Limited

Soren Skak Jensen

Koen Bernard Vos

Karsten Vandborg Sorensen

Renat Vafin

Jonas Lindblom

Soren Andersen

Jon Bergenheim

Stefan Strommer

Julian Spittka

Henrik Astrom

Soren Vang Anderson

Henrik Aström

A first user terminal, host terminal, method and program. The first terminal comprises: a transceiver for communicating with a plurality of other user terminals over a communication network; and communications processing apparatus, coupled to the transceiver, and arranged to participate in a call with a selected number of the other user terminals via the transceiver and communication network, the call including transmission of a voice signal from the first user terminal. The communications processing apparatus is operable in a mode whereby it temporarily discontinues transmission of the voice signal in response to detecting less than a predetermined level of activity on said voice signal, and the communications processing apparatus is further configured to selectively enable that mode in dependence on the selected number of other user terminals in the call.

Controlling multi-party communications

Processing of a signal received at a node in a network is described in which effects on the signal caused by applying an action to a first part of the signal are quantified based on characteristics of the first part of the signal and effects on the signal caused by not applying the action to the first part of the signal are quantified based on characteristics of a second, subsequent part of the signal. The action may then be selectively applied either to the first part of the signal or to the second part of the signal based upon the quantifications. In some embodiments, the action is applied to a portion of the signal for which the effects on at least one measure of the signal quality are less detrimental.

Method of transmitting data in a communication system

A method, system and program for encoding and decoding speech according to a source-filter model whereby speech is modelled to comprise a source signal filtered by a time-varying filter. The method comprises: receiving a speech signal comprising successive frames, for each of a plurality of frames of the speech signal, deriving a first line spectral frequency vector for a first portion of the frame, and a second line spectral frequency vector for a second portion of the frame, and determining a transmit line spectral frequency vector and an interpolation factor based on the first and second line spectral frequency vectors, and on the transmit line spectral frequency vector for a preceding one of the frames.

Speech encoding and decoding utilizing line spectral frequency interpolation

A method and apparatus for transmitting an audio signal over a communication channel comprising encoding the audio signal with an encoderusing a first sampling rate, filtering the audio signal using a first cut off frequency, the first cut off frequency being chosen in dependence upon the first sampling rate, and transmitting the encoded and filtered audio signal over the communication channel. The presence of a condition in which the sampling rate of the encoderis to be switched to a second sampling rate at a switching time is determined and if the condition has been determined to be present, the cut off frequency used in the filtering step is gradually changed from the first cut off frequency to a second cut off frequency, the second cut off frequency being chosen in dependence upon the second sampling rate, such that the audio bandwidth of the transmitted signal changes gradually when the sampling rate is switched to the second sampling rate.

Encoding and decoding speech signals

A method, system and computer program for encoding speech according to a source-filter model. The method comprises deriving a spectral envelope signal representative of a modelled filter and a first remaining signal representative of a modelled source signal, and deriving a second remaining signal from the first remaining signal by, at intervals during the encoding: exploiting a correlation between approximately periodic portions in the first remaining signal to generate a predicted version of a later portion from a stored version of an earlier portion, and using the predicted-version of the later portion to remove an effect of said periodicity from the first remaining signal. The method further comprises, once every number of intervals, transforming the stored version of the earlier portion of the first remaining signal prior to generating the predicted version of the respective later portion.

Predictive speech signal coding

A method of transmitting over a network a signal comprising a plurality of data elements the method comprising; receiving the signal at a terminal; determining a transmission delay of at least one data element; estimating a first component of the transmission delay; determining a second component of the transmission delay by removing the first component of the transmission delay from the transmission delay; and determining a receiver delay to be applied between receiving at the terminal and outputting from the terminal one of said plurality of data elements, in dependence on the second component of the transmission delay.

A method of processing a signal received at a node in a network, comprising the steps of; receiving the signal at the node; determining characteristics of a first part of the signal; determining characteristics of a second part of the signal that is subsequent to the first part of the signal; quantifying an effect on the signal caused by applying an action to the first part of the signal, based on characteristics of the first part of the signal; quantifying an effect on the signal caused by not applying the action on the first part of the signal, based on characteristics of the second part of the signal; applying the action to the first part of the signal if it is determined that the effect on the signal caused by applying the action to the first part of the signal is less detrimental to at least one measure of the signal quality than the effect on the signal caused by not applying the action to the first part of the signal.

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Stockholm, Sweden

Soren Skak Jensen