Abstract: A method and system for the estimation of the effect of packet loss on a viewer's subjective perception of a packet video stream. The method involves estimating a quality metric for every frame in the video stream, accumulating such metrics over time, and transforming the result into a Mean Opinion Score (“MOS”) which represents the viewer's subjective perception of the video stream. The method takes into account various factors such as frame rate, frame types and sizes, decoding algorithms, propagated error rates, and the effect of video content on viewer perception. The method can be used for both encrypted and unencrypted video streams.

Abstract: A method and system for the estimation of the effect of packet loss on a viewer's subjective perception of a packet video stream. The method involves estimating a quality metric for every frame in the video stream, accumulating such metrics over time, and transforming the result into a Mean Opinion Score (“MOS”) which represents the viewer's subjective perception of the video stream. The method takes into account various factors such as frame rate, frame types and sizes, decoding algorithms, propagated error rates, and the effect of video content on viewer perception. The method can be used for both encrypted and unencrypted video streams.

Abstract: A method for estimating a subjective quality of a signal carried over a transmission path. The transmission path is monitored at periodic intervals. For each of the periodic intervals, at least one impairment factor is measured, an estimated effect of each of the impairment factors is determined using at least one value, and an estimated subjective quality of the signal is determined using the estimated effect of each of the impairment factors. Further, an estimated combined subjective quality of the signal is determined using the estimated subjective quality for at least two of the periodic intervals.

Abstract: A system and method for providing service quality metrics related to the quality of service provided by a Voice over Internet Protocol (“VoIP”) network to voiceband modems or fax machines communicating over the VoIP network. The system utilizes a multi-state Markov model to evaluate the quality of service provided by the VoIP network and provides an assessment of the suitability of the network to carry voiceband data traffic.

Abstract: A network monitoring system for packet based multimedia signal transmission systems which identifies network problems that may affect multimedia performance and provides guidance as to the location of such problems within the network.

Abstract: The present invention provides a system and method for improving the quality of real-time multimedia sessions wherein each endpoint of a real-time packet stream transmits (1) feedback reports that describe the quality of the stream received by the endpoint and (2) forward reports that are based on the feedback reports received by the endpoint and that describe the quality of the stream received by the other, remote endpoint. The forward reports are used by routers to re-route packets around problems in the network that are located between the router and the remote endpoint.

Abstract: The present invention provides a system and method for prioritizing delay-sensitive packets relative to each other for transmission from a router in a network, based on a delay variation estimated for each delay-sensitive packet by a quality of service monitor. In accordance with the present invention, late delay-sensitive packets are assigned a higher priority than, and are transmitted before, other delay-sensitive packets, thereby reducing the level of jitter and improving the quality of the packet streams that comprise late delay-sensitive packets.

Abstract: A subjective quality monitoring system for packet based multimedia signal transmission systems which determines, during more than one interval of a single call, the level of one or more impairments and determines the effect of said one or more impairments on the estimated subjective quality of said multimedia signal. The quality monitoring system comprises a plurality of quality monitoring functions located at the multimedia to packet conversion points.