Abstract: Control of a data packet buffer in a communication system and a data packet queue in a transmission link are shown. The queue stores a plurality of received data packets that are intended for transmission over a wireless interface. Selected packets are discarded from the queue without the selected packets having been transmitted. A packet is selected for discarding depending on at least the length of time the packet has been stored in the queue. The discarding of a selected packet is effectuated on condition that at least a predetermined time period has elapsed since a previous discarding of a packet has taken place. Such a solution is advantageous in that, for varying transmission bandwidth conditions in the transmission link, it is possible to achieve good link utilization and throughput, while at the same time enabling a low end-to-end delay for packets transmitted in the link.

Abstract: Method, transmitter and computer program product for transmitting data of a real-time communication event from the transmitter to a jitter buffer of a receiver. The method comprises jointly determining (i) at least one processing parameter describing how data is to be processed for transmission from the transmitter to the jitter buffer, and (ii) jitter buffer control information for indicating to the receiver how to control a state of the jitter buffer. The jitter buffer control information is transmitted to the receiver. Data is processed for transmission from the transmitter to the jitter buffer in accordance with the determined at least one processing parameter. The processed data is transmitted from the transmitter to the jitter buffer of the receiver.

Abstract: Methods, transmitter, receiver and computer program product for transmitting or receiving data of a real-time communication event, the data being transmitted from the transmitter to a jitter buffer of the receiver. At least one processing parameter describing how data is to be processed for transmission from the transmitter to the jitter buffer in the real-time communication event is determined at the transmitter. Data is processed for transmission from the transmitter to the jitter buffer in accordance with the determined at least one processing parameter. Control information based on the determined at least one processing parameter is transmitted from the transmitter to the receiver, wherein the control information is for use by the receiver to control a state of the jitter buffer. The processed data is transmitted from the transmitter to the jitter buffer of the receiver in the real-time communication event.

Abstract: Method, transmitter and computer program product for transmitting data of a real-time communication event from the transmitter to a jitter buffer of a receiver. Jitter buffer state information is received at the transmitter from the receiver, the jitter buffer state information indicating a state of the jitter buffer. At least one processing parameter is controlled based on the received jitter buffer state information, the at least one processing parameter describing how data is to be processed for transmission from the transmitter to the jitter buffer in the real-time communication event. Data is processed for transmission from the transmitter to the jitter buffer in accordance with the determined at least one processing parameter. The processed data is transmitted from the transmitter to the jitter buffer of the receiver in the real-time communication event.

Abstract: A method comprising: encoding a video image at each of a plurality of frames, including by using inter frame encoding to encode at least portions of some of the frames, thereby generating an encoded video stream; transmitting the encoded video stream over a lossy channel to be decoded at a receiver to produce decoded video; and performing a recovery operation to refresh the encoding of the video image, cutting off error propagation that has occurred in the decoded video due to an effect of inter prediction in presence of loss over said channel; wherein the recovery operation is triggered by a report fed back from the receiver indicative of loss; and wherein the recovery operation is performed over a plural number of frames, refreshing the encoding of different partial frame regions at different respective frames.

Abstract: A method of performing a rate-distortion optimization process comprising, for each of a plurality of target image portions to be encoded in each of a plurality of frames, selecting a preferred one of a set of encoding modes by optimizing a function comprising an estimate of distortion for the target image portion and a measure of bit rate required to encode the target image portion, wherein the estimate of distortion is based on source coding distortion and an estimate of a distortion that would be experienced due to possible loss over the channel; encoding the target image portion into the encoded video stream using the selected encoding mode; and transmitting the encoded video stream over the channel. The rate-distortion optimization process for a current one of the frames is performed in dependence on feedback received from the receiving terminal based on an earlier one of the frames.

Abstract: A method of performing a rate-distortion optimization process comprising selecting a preferred encoding mode by optimizing a function comprising an estimate of distortion for a target image portion and a measure of bit rate required to encode that portion. The estimate of distortion is based on source coding distortion and an estimate of error propagation distortion due to loss. The method further comprises transmitting the same encoded version of the video stream from the transmitting terminal to each of a plurality of receiving terminals over respective lossy channels, using the same rate-distortion optimization process in relation to each of the plurality of receiving terminals, making the same encoding mode selection per target image portion based on the same optimization of said function. The estimate of error propagation distortion comprises an aggregate estimate of error propagation distortion that would be experienced due to possible loss over the plurality of channels.

Abstract: A method and system for regenerating wideband speech from narrowband speech. The method comprises: receiving samples of a narrowband speech signal in a first range of frequencies; modulating received samples of the narrowband speech signal with a modulation signal having a modulating frequency adapted to upshift each frequency in the first range of frequencies by an amount determined by the modulating frequency wherein the modulating frequency is selected to translate into a target band a selected frequency band within the first range of signals; filtering the modulated samples using a high pass filter to form a regenerated speech signal in the target band, wherein the lower limit of the high pass filter defines the lowermost frequency in the target band; and combining the narrow band speech signal with the regenerated speech signal in the target band to regenerate a wideband speech signal.

Abstract: A method comprising: for each target image portion to be encoded in a frame, selecting one of a set of encoding modes by optimizing a function comprising an estimate of distortion for the target image portion and a measure of bit rate required to encode the target image portion, encoding the target image portion into the encoded video stream using the selected mode. The encoded video stream is transmitted over a lossy channel. An error propagation distortion map is maintained, which comprises a plurality of error propagation distortion values mapping to respective frame partitions, the error propagation distortion values being based on previous encoding mode selections. The estimate of distortion used to select the encoding mode for each of the target image portions is based on a corresponding portion from the error propagation distortion map, and that corresponding portion is constrained to being co-located with the target image portion.

Abstract: Correction data units for data packets of a data stream are generated. A correction data unit is based on a set of the data packets of the stream. The stream is transmitted over a lossy communication channel. A performance measure to be optimized is selected, which relates to the recovery of lost data packets of the stream. A coding requirement is determined. For the generation of the correction data units, it is determined, within the constraints of the coding requirement and based on previously generated correction data units, which of the data packets in the stream to include in the set on which the generation of the correction data unit is to be based to thereby optimize the selected performance measure. A generated correction data unit is generated based on a respective set of the data packets of the stream. The generated correction data units are included in the stream.

Abstract: A method of encoding a video stream comprising: for each of a plurality of first image portions to be encoded in an outgoing video stream, selecting a preferred one of a set of potential encoding modes using a first process comprising an estimation of distortion of the first image portion and a measure of bit rate required to encode the first image portion for each of the first image portion's potential encoding modes; encoding each of the first image portions of the outgoing stream using the respective selected encoding mode; for each of a plurality of second image portions of a video stream, applying a second process comprising at least an estimation of distortion of the second image portion; and using an output of the second process resulting from the second image portions to bias the first process in said selection of the encoding modes for the first portions.

Abstract: A method of encoding an outgoing video stream comprising a plurality of frames, each frame comprising a plurality of image portions, the method including for each target image portion to be encoded, selecting a preferred one of a set of encoding modes by optimizing a function comprising an estimate of distortion and a measure of bit rate required to encode the target image portion; encoding the target image portion into the outgoing video stream using the selected encoding mode; and transmitting the encoded outgoing video stream over a lossy channel. The estimate of distortion comprises a first term representing source coding distortion, and a bias term representing an estimate of distortion that would be experienced due to loss over said channel. The bias term is determined based on a trained parameter trained based on a sample video stream.

Abstract: A video coding method includes for each target image portion to be encoded, selecting a preferred one of a set of encoding modes by optimizing a function comprising an estimate of distortion and a measure of bit rate required to encode the target image portion, the encoding modes comprising at least an intra frame mode and an inter frame mode; and transmitting the encoded video stream over a lossy channel. The estimate of distortion is based on a contribution from possible new loss over the channel comprising possible loss of the target block, and on a contribution from possible past loss over the channel comprising possible loss in a history of the encoded video stream upon which decoding of the target portion depends. The method includes accumulating the contribution from past loss over time, such that the estimate of distortion grows irrespective of the contribution from new loss.

Abstract: A system and method for processing a narrowband speech signal comprising speech samples in a first range of frequencies. the method comprises: generating from the narrowband speech signal a highband speech signal in a second range of frequencies above the first range of frequencies; determining a pitch of the highband speech signal; using the pitch to generate a pitch-dependent tonality measure from samples of the highband speech signal; and filtering the speech samples using a gain factor derived from the tonality measure and selected to reduce the amplitude of harmonics in the highband speech signal.

Abstract: The present invention provides a technique for performing one or more aspects of video coding such as quantization, intra prediction coding or inter prediction coding in dependence on a perceptual model taking into account human sensitivity to data in the video signal. The perceptual model may relate to spatial frequency, temporal frequency, contrast sensitivity, colour sensitivity, a structural metric, and/or one or more parameters affecting perception such as motion in the video, the distance of a recipient user from the screen, and the size, aspect ratio or resolution of the screen of the recipient terminal.

Abstract: A system for enhancing a signal regenerated from an encoded audio signal. The system comprises a decoder arranged to receive the encoded audio signal and produce a decoded audio signal, a feature extraction means arranged to receive at least one of the decoded and encoded audio signal and extract at least one feature from at least one of the decoded and encoded audio signal, a mapping means arranged to map the at least one feature to an enhancement signal and operable to generate and output the enhancement signal, whereby the enhancement signal has a frequency band that is within the decoded audio signal frequency band, and a mixing means arranged to receive the decoded audio signal and the enhancement signal and mix the enhancement signal with the decoded audio signal.

Abstract: A method of compressing video data, the method comprising: providing image data for each of a plurality of image portions; determining an index value for each of said image portions based on the respective image data; for a target image portion to be encoded, identifying a matching image portion having an index value within a search threshold of the index value of the target image portion; and generating difference data for the target image portion relative to the matching image portion, and including the difference data in an encoded video signal.

Abstract: A method of selecting reference blocks for intra or inter prediction coding of a current block of a video signal. Each reference blocks is selected by: (i) determining a group of candidate blocks comprising at least some candidate blocks other than immediately adjacent spatial neighbours of the current block; and (ii) selecting one of the candidate blocks as the reference block based on a second metric, different from the first metric, the second metric relating to a number of bits that would be required in the encoded bitstream to encode both the residual block and the side information identifying the respective reference block.

Abstract: The present invention provides an encoded bitstream and corresponding decoder. An encoded bit stream of compressed video data represents a plurality of successive video frames with each frame being divided into a plurality of portions and each portion corresponding to a plurality of pixels. The encoded bit stream comprises: a set of quantized transform domain coefficients representing a first one of said portions; difference data for a second one of said portions, wherein the difference data defines a difference between transform domain coefficients of the first portion and the predicted second portion, such that the second portion can be predicted from the first portion; and an address specifying the location of the first portion in terms of a whole number of said portions instead of a pixel offset.

Abstract: An encoder stage, and corresponding encoded bitstream and decoder. The encoder stage comprises: a variable length encoder for encoding an input signal; and a counter configured to dynamically detect an observed frequency at which different symbols are found to occur within each of a plurality of predetermined portions of the input signal, prior to the symbols of each respective portion being encoded by the variable length encoder. The variable length encoder is configured to encode the symbols of each portion using variable length coding performed in dependence on the observed frequencies detected within the respective portion of the input signal, to generate an encoded bitstream comprising the encoded symbols along with an additional element indicating information regarding the observed frequencies detected for each portion, and to output the encoded bitstream to at least one of a storage medium and a transmission medium for supply to a decoder.