Samir Mohamed

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An important and unsolved problem today is the automatic quantification of the quality of video flows transmitted over packet networks. In particular, the ability to perform this task in real time (typically for streams sent themselves in real time) is specially interesting. The problem is still unsolved because there are many parameters affecting video(More)
This paper addresses the problem of quantitatively evaluating the quality of a speech stream transported over the Internet as perceived by the end-user. We propose an approach being able to perform this task automatically and, if necessary, in real time. Our method is based on using G-networks (open networks of queues with positive and negative customers)(More)
The goal of this paper is to show how Artificial Neural Networks (ANNs) can be used to mimic the way human subjects estimate the quality of audio signals when distorted by changes in several parameters that affect the transmitted audio quality. To validate the approach, we carried out the subjective quality experiment for speech signals distorted by(More)
There is a great demand to assess video quality transmitted in real time over packet networks, and to make this assessment in real time too. Quality assessment is achieved using two types of methods: objective or subjective. Subjective methods give more reliable results than objective methods; the latter do not always correlate well with human perception.(More)
Transmitting digital audio signals in real-time over packet switched networks (e.g., the Internet) has set forth the need for developing signal processing algorithms that objectively evaluate audio quality. So far, the best way to assess audio quality are subjective listening tests, the most commonly used being the Mean Opinion Score (MOS) recommended by(More)
We have recently proposed a novel, non–intrusive, real– time approach to measuring the quality of an audio (or speech) stream transmitted over a packet network. The proposed approach takes into account the diversity of the factors which affect audio quality, including encoding parameters and network impairments. The goal of this method is to overcome the(More)
The aim of this work is to study the effect of foliar application of various concentrations (50, 100 and 200 ppm) of ascorbic acid and niacin on protein, oil, fatty acids and antibacterial activity of bitter lupine (Lupinus termis L.) seeds. The results obtained showed that, foliar application of both ascorbic acid and niacin had significant effect on(More)