Abstract: Non-intrusive speech-quality assessment uses vocal-tract models, in particular for testing telecommunications systems and equipment. This process requires reduction of the speech stream under assessment into a set of parameters that are sensitive to the types of distortion to be assessed. Once parameterized, the data is used to generate a set of physiologically-based rules for error identification, using a parametric modeling of the shape of the vocal tract itself, by comparison between derived parameters and the output of models of physiologically realistic forms for the vocal tract, and the application of physical constraints on how these can change over time.

Abstract: The present invention relates to an apparatus and method for normalization of an image signal, particularly for use in perceptual video and still image quality measurement when the quality measurement is achieved by making a comparison between a reference signal and a decoded signal. The invention provides a method for normalizing a decoded image signal in relation to a reference image signal to generate a normalized image signal comprising the steps of: generating a non-linear transformation vector in dependence upon at least one component of the decoded image signal and at least one component of the reference image signal; and applying said non-linear transformation vector to at least one component of the decoded image signal to generate a normalized image signal. Methods and apparatus for perceptual video and still image quality measurement using said method are also provided.

Abstract: This invention relates to generation of a sample error coefficient suitable for use in an audio signal quality assessment system. The invention provides a method of determining a sample error coefficient between a first signal and a similar second signal comprising the steps of: determining a first periodicity measure from the first signal; determining a second periodicity measure from the second signal; generating a ratio in dependence upon said first periodicity measure and said second periodicity measure; and determining a sampling rate error coefficient in dependence upon said ratio.

Abstract: The present invention relates to an apparatus and method for processing images, in particular for determining the degree of blockiness in coded images.

Abstract: This invention relates to alignment of signals, particularly for use in a quality assessment system.

Abstract: This invention provides a parameter for use in assessing video quality based on temporal frame freezing for use in an apparatus and method for perceptual video quality measurement. The invention provides a method of generating a freeze frame parameter relating to the perceptual impact of frozen frames in a video signal comprising the steps of: identifying frozen frames; identifying a freeze event comprising a plurality of consecutive frozen frames, the freeze event having a duration in dependence upon the number of frozen frames in said sequence; defining a set of duration ranges; and generating a freeze frame parameter in dependence upon the number of freeze events having a duration falling within each duration range. Methods and apparatus for perceptual video quality measurement using the method are also provided.

Abstract: The present invention relates to an apparatus and method for processing images, in particular for determining the degree of blockiness in coded images. The invention comprises apparatus and methods for determining a degree of blockiness in a digital image comprising blocks each block comprising a plurality of rows and a plurality of columns of pixels each pixel having a value by performing the steps of: for each block determining an intra block measure in dependence upon the values of a set of pixels within said block; and determining said measure in dependence upon a plurality of said intra block measures corresponding to each block. Method and apparatus for generating a quality measure in dependence upon the measure of blockiness are also provided.

Abstract: This invention relates to a method of defining an optimised set of test sequences for use with a packet based perceptual quality evaluation processor associated with an edge-device that receives packets containing speech data and converts said packets to a speech signal, the method comprising the steps of: defining a set of quality targets which should be produced when a test sequence of packets is processed by the edge-device; determining a value for a degradation parameter for each quality target wherein a test sequence having a degradation according to said value will substantially produce said quality target when said test sequence is processed by the edge-device.

Abstract: The present invention relates to detection of echo in telecommunications networks. The invention provides a method of echo detection comprising the steps of: generating a series of inbound vectors for an inbound signal; generating a series of outbound vectors for an outbound signal; repeating a predetermined number of comparison steps comprising the sub-steps of selecting an outbound vector from the outbound vectors; selecting an inbound vector from the inbound vectors; comparing said outbound vector with said inbound vector and with successive inbound vectors to generate a plurality of similarity metrics; and determining a relative position of the compared outbound vector having maximum correlation with said inbound vector; and counting the number of times each relative position is determined to be the position of maximum correlation.

Abstract: The present invention relates to the problem of estimating the effect of packet transmission impairments, including packet loss, on the subjective quality of a video transmission where frames of data relating to the same video frame or field are permitted to span more than one packet. The invention provides a method of assessing quality of a video signal comprising a sequence of video frames received via a packet switched network using a parameter which is a weighted sum of two counters where the first counter is incremented in dependence of the total number of packets in frames determined to have been received with one or more lost packets and the second counter is incremented in dependence of the number of packets following the first lost packet in each frame and the lost packet itself.

Abstract: This invention relates to a non-intrusive video quality assessment system. A method and apparatus are provided in which video frame parameters are extracted from a sequence of packets by generating a first video quality parameter for each group of packets associated with a particular frame of video data in dependence upon the frame rate of the video stream; and generating a second video quality parameter for each of said group of packets in dependence upon the size of encoded data comprising the video frame.

Abstract: Non-intrusive speech quality assessment method and apparatus for storing a sequence of intercepted packets associated with a call, each packet containing speech data, and an indication of a transmission time of the packet; storing with each intercepted packet an indication of an intercept time of the packet; extracting a set of parameters from the sequence of packets; and generating an estimated mean opinion score in dependence upon the set of parameters. The extracting step comprises the sub steps of: generating a jitter parameter for each packet of the sequence of stored packets; generating a long term average jitter parameter for the stored packet; and generating a differential jitter parameter in dependence upon the jitter parameter for the stored packet and the long term average jitter parameter.

Abstract: This invention relates to alignment of signals, particularly for use in a quality assessment system.

Abstract: This invention provides a parameter for use in assessing video quality based on temporal frame freezing for use in an apparatus and method for perceptual video quality measurement. The invention provides a method of generating a freeze frame parameter relating to the perceptual impact of frozen frames in a video signal comprising the steps of: identifying frozen frames; identifying a freeze event comprising a plurality of consecutive frozen frames, the freeze event having a duration in dependence upon the number of frozen frames in said sequence; defining a set of duration ranges; and generating a freeze frame parameter in dependence upon the number of freeze events having a duration falling within each duration range. Methods and apparatus for perceptual video quality measurement using the method are also provided.

Abstract: The present invention relates to an apparatus and method for normalisation of an image signal, particularly for use in perceptual video and still image quality measurement when the quality measurement is achieved by making a comparison between a reference signal and a decoded signal. The invention provides a method for normalising a decoded image signal in relation to a reference image signal to generate a normalised image signal comprising the steps of: generating a non-linear transformation vector in dependence upon at least one component of the decoded image signal and at least one component of the reference image signal; and applying said non-linear transformation vector to at least one component of the decoded image signal to generate a normalised image signal. Methods and apparatus for perceptual video and still image quality measurement using said method are also provided.

Abstract: The present invention relates to an apparatus and method for processing images, in particular for determining the degree of blockiness in coded images. The invention comprises apparatus and methods for determining a degree of blockiness in a digital image comprising blocks each block comprising a plurality of rows and a plurality of columns of pixels each pixel having a value by performing the steps of: for each block determining an intra block measure in dependence upon the values of a set of pixels within said block; and determining said measure in dependence upon a plurality of said intra block measures corresponding to each block. Method and apparatus for generating a quality measure in dependence upon the measure of blockiness are also provided.

Abstract: The present invention relates to an apparatus and method for processing images, in particular for determining the degree of blockiness in coded images.

Abstract: A non-intrusive speech quality assessment system. A method and apparatus for training a quality assessment tool in which a database comprising a plurality of samples, each with an associated mean opinion score, is divided into a plurality of distortion sets of samples according to a distortion criterion; and a distortion specific assessment handler for each distortion set is trained, such that a fit between a distortion specific quality measure generated from a distortion specific plurality of parameters for a sample and the mean opinion score associated with said sample is optimised. A method and apparatus for assessing speech quality in a telecommunications network in which a dominant distortion type is determined for a sample; a distortion specific plurality of parameters are combined to provide a distortion specific quality measure for each sample; and a quality measure is generated in dependence upon the distortion specific quality measure.

Abstract: Non-intrusive speech quality assessment method and apparatus for: storing a sequence of intercepted packets associated with a call, each packet containing speech data, and an indication of a transmission time of the packet; storing with each intercepted packet an indication of an intercept time of the packet; extracting a set of parameters from the sequence of packets; and generating an estimated mean opinion score in dependence upon the set of parameters. The extracting step comprises the sub steps of: generating a jitter parameter for each packet of the sequence of stored packets; and generating a consecutive positive jitter parameter for the stored packet.

Abstract: The present invention relates to detection of echo in telecommunications networks. The invention provides a method of echo detection comprising the steps of: generating a series of inbound vectors for an inbound signal; generating a series of outbound vectors for an outbound signal; repeating a predetermined number of comparison steps comprising the sub-steps of selecting an outbound vector from the outbound vectors; selecting an inbound vector from the inbound vectors; comparing said outbound vector with said inbound vector and with successive inbound vectors to generate a plurality of similarity metrics; and determining a relative position of the compared outbound vector having maximum correlation with said inbound vector; and counting the number of times each relative position is determined to be the position of maximum correlation.