Communications - Scientific Letters of the University of Zilina, 2016 (vol. 18), issue 1

Articles

Monitoring Voip Speech Quality for Chopped and Clipped Speech

Andrew Hines, Jan Skoglund, Anil C. Kokaram, Naomi Harte

Communications - Scientific Letters of the University of Zilina 2016, 18(1):3-10 | DOI: 10.26552/com.C.2016.1.3-10

Real-time monitoring of speech quality for VoIP calls is a significant challenge. This paper presents early work on a no-reference objective model for quantifying perceived speech quality in VoIP. The overall approach uses a modular design that will be able to help pinpoint the reason for degradations as well as quantifying their impact on speech quality. The model is being designed to work with narrowband and wideband signals. This initial work is focused on rating amplitude clipped or chopped speech, which are common problems in VoIP. A model sensitive to each of these degradations is presented and then tested with both synthetic and real examples...

A Black Box Analysis of Webrtc Mouth-To-Ear Delays

Oliwia Komperda, Hugh Melvin, Peter Pocta

Communications - Scientific Letters of the University of Zilina 2016, 18(1):11-16 | DOI: 10.26552/com.C.2016.1.11-16

Due to the recent shift toward cloud based computing, some of the world's leading standardization bodies have combined forces to provide guidelines and standards for native implementation of RealTime Communication (RTC) in the browsers. The World Wide Web Consortium (W3C) works on WebRTC APIs [1], while the Internet Engineering Task Force (IETF) is concerned with underlying standards [2]. Their efforts led to the development of WebRTC project by Google, Mozilla and Opera, which is an open framework that allows browsers to be RTC ready [3]. In this paper, we examine WebRTC from a Quality of Service (QoS) perspective, focusing on Mouth-to-Ear (M2E) delays...

A Black-Box Analysis of the Extent of Time-Scale Modification Introduced by WEBRTC Adaptive Jitter Buffer and its Impact on Listening Speech Quality

Yusuf Cinar, Hugh Melvin, Peter Pocta

Communications - Scientific Letters of the University of Zilina 2016, 18(1):17-22 | DOI: 10.26552/com.C.2016.1.17-22

WebRTC is an open-source platform for real-time communications over the web and has been experiencing widespread adoption in recent years. WebRTC clients employ the technique of time scaling of packets to cope with the impact of network jitter and/or clock skew. A black-box study presented in this paper focuses on two aspects, namely time scale modification behaviour under different packet arrival interval and its impact on the listening quality perceived by the end user. Specifically, we examine the MOS scores predicted by the POLQA speech quality prediction model. Our tests involve both iSAC and Opus codecs, two of the widely used WebRTC codecs....

An Impact of Narrowband Speech Codec Mismatch on a Performance of GMM-UBM Speaker Recognition over Telecommunication Channel

Jozef Polacky, Peter Pocta, Roman Jarina

Communications - Scientific Letters of the University of Zilina 2016, 18(1):23-28 | DOI: 10.26552/com.C.2016.1.23-28

The automatic identification of person's identity from their voice is a part of modern telecommunication services. In order to execute the identification task, speech signal has to be transmitted to a remote server. So a performance of the recognition/identification system can be influenced by various distortions that occur when transmitting speech signal through a communication channel. This paper studies an effect of telecommunication channel, particularly commonly used narrowband (NB) speech codecs in current telecommunication networks, on a performance of automatic speaker recognition in the context of a channel/codec mismatch between enrollment...

A New Algorithm for Key Frame Xtraction Based on Depth Map Using Kinect

Peter Sykora, Patrik Kamencay, Robert Hudec, Miroslav Benco

Communications - Scientific Letters of the University of Zilina 2016, 18(1):29-34 | DOI: 10.26552/com.C.2016.1.29-34

In this paper, a new algorithm for key frame extraction based on depth map for hand gesture recognition is presented. The all input sequences are captured by Microsoft Kinect camera system. These methods extract three key frames from captured depth video sequence. These key frames describe dynamic gesture. The proposed extraction method is composed of two parts. The first part, labelled as space segmentation extracts the region of hand from background. The second part labelled as time segmentation splits captured sequence into three parts and marks one frame per part as the key frame. A new gesture database for evaluation of proposed method was created....

Resources Reservation in the Segment of Optical Network with Obs

Michaela Solanska, Miroslav Markovic, Milan Dado

Communications - Scientific Letters of the University of Zilina 2016, 18(1):35-39 | DOI: 10.26552/com.C.2016.1.35-39

The growing demands on transmission quality, flexibility and granularity can be achieved by powerful reservation protocols which are an essential part of networks with burst switching. In today's high-speed optical networks there exist a lot of reservation protocols. In this article we present a design of a new reservation protocol called Search&Compare. This reservation protocol is designed according to the well-known Segment-based Robust Fast Optical Reservation Protocol. Search&Compare is parallel-segment based and uses parallel link reservation. Our goal is to describe the behavior of reservation protocol in the transmission with setting...

Covert Channel in RTP Payload Using a Pointer in Sip Header

Miroslav Voznak, Ivo Zbranek, Miralem Mehic, Dan Komosny, Homero Toral-Cruz, Jerry Chun-Wei Lin

Communications - Scientific Letters of the University of Zilina 2016, 18(1):40-47 | DOI: 10.26552/com.C.2016.1.40-47

The paper addresses the issue of hiding data in the network flow. The authors discuss a new proposal of the steganographic approach in IP telephony: transmitting texts using the pointer in the SIP header by means of a data stream within the RTP protocol. This method is based on tagging the binary sequences in payload of the RTP packets, with the individual binary sequences representing individual steganogram characters. Subsequently, the position of the binary sequences is recorded in the SIP header in the Via field and the branch parameter. The proposed way of hidden data transmission cannot be detected by existing anomaly detectors; and does not...

Automatically Provisioned Embedded Communication System Based on Openwrt Platform

Jiri Slachta, Miroslav Voznak, Dan Komosny, Homero Toral-Cruz, Peppino Fazio

Communications - Scientific Letters of the University of Zilina 2016, 18(1):48-55 | DOI: 10.26552/com.C.2016.1.48-55

The article deals with a design of a system that provides tools for creation of automatically provisioned embedded communication system and its components. As the key feature of the BEESIP platform (Bright Efficient Embedded Solution for IP Telephony) a unique building and provisioning system of the network devices has been developed allowing the administrators to fully control the firmware and configuration of the devices even in the remote and inaccessible locations. The process of custom firmware building and device provisioning eases the mass deployment of the BEESIP based hardware to cover the needs of small to medium business in the vast range...

Real-Time Facial Motion Capture Using a Webcam

Peter Kajan, Patrik Kamencay, Jan Hlubik, Robert Hudec, Miroslav Benco, Peter Sykora

Communications - Scientific Letters of the University of Zilina 2016, 18(1):56-61 | DOI: 10.26552/com.C.2016.1.56-61

In this paper, we create a software which would be able to combine marker and marker-less face tracking for the purpose of the creation of the accurate and real time running 3D facial animation inside the Cinema 4D. The aim is develop a powerful piece of the software that can provide facial motion capture and share the motion coordinates on the server in real time. The software solution includes tracking software which is written in C++ and provides real time face tracking. Tracking data are sent to the server in real time. Main benefit is that this solution can provide tracking data on the server for any third software. At least, the smooth run of...

Modelling of Data Communication over Medium-Voltage Power Distribution Lines

Jaromir Hrad, Jiri Vodrazka

Communications - Scientific Letters of the University of Zilina 2016, 18(1):62-66 | DOI: 10.26552/com.C.2016.1.62-66

The paper is dedicated to different topologies of medium-voltage power distribution lines with respect to their properties influencing the transmission of communication signals. We provide very basic introduction to the problems of signal transmission over these lines, discuss their parameters and examine the typical behaviour and characteristics. We conclude our considerations with some specific recommendations concerning the most advantageous configurations for the purposes of Power Line Communication (PLC). The data transmission capacity is calculated for different topologies and network conditions.

Sensitivity of International Roughness Index to Distresses of Cement Concrete Road Surfaces

Peter Mucka

Communications - Scientific Letters of the University of Zilina 2016, 18(1):67-74 | DOI: 10.26552/com.C.2016.1.67-74

The paper examined the sensitivity of International Roughness Index (IRI) to the local discontinuities (various distresses, joints, joint and surface defects, other road features, etc.) of the cement concrete (CC) pavements. About 5 300 road records of total length 470 km from Long Term Pavement Performance (LTPP) program were processed. The raw profiles were separated into a random part and a distress part using the median filtering method. The median filter order was set to identify distresses of variable maximum width from 20 to 40 cm, and minimal height, 3 mm. About 26 000 distresses were separated and their dimensions were identified. The raw...

Infrastructure Operation Reliability in Built-Up Areas

Sarka Krocova, Miloslav Rezac

Communications - Scientific Letters of the University of Zilina 2016, 18(1):75-78 | DOI: 10.26552/com.C.2016.1.75-78

Reliability and safety of energy, drinking water deliveries and draining wastewater from built- up areas in cities and villages have many proportions and technical-operational conditions. Among basic requirements of the use of all types of residential or manufacturing objects in the 21st century is reliable delivery of drinking water, draining and cleaning of urban and industrial sewage. Disturbance or putting out of service of this type of infrastructure has always a domino effect. Gradually growing reliance of user base of all types of drinking water consumers leads especially in the section of the public or private infrastructure to restriction...

Porter's Analysis as a Standardized Process Applicable in Industrial Companies

Roman Kozel, Milan Mikolas, Sarka Vilamova, Katerina Chuchrova, Marian Piecha

Communications - Scientific Letters of the University of Zilina 2016, 18(1):79-84 | DOI: 10.26552/com.C.2016.1.79-84

The Location of LPG Filling Stations and Potential Risks of Incidents

Ondrej Varta, Sarka Krocova

Communications - Scientific Letters of the University of Zilina 2016, 18(1):85-88 | DOI: 10.26552/com.C.2016.1.85-88

The risk of unsuitable placement of LPG (i.e. Liquid Petroleum Gas) propane-butane filling stations in densely populated areas or in the immediate vicinity of busy roads may have, in the event of fire or explosion, incalculable consequences in terms of fatal or serious accidents and cause considerable economic damage to property. As a consequence, the positioning of any such LPG filling station should always be of crucial importance already in the filling station planning stage and its placement should be carefully assessed. The present paper aims at outlining a particular method of evaluating risks resulting from incorrect placement of an LPG filling...

Fractographic Analysis of Hardox Steels Research in the Field of High-Cycle Fatigue Regime

Pawel Szataniak, Magdalena Mazur, Robert Ulewicz, Frantisek Novy

Communications - Scientific Letters of the University of Zilina 2016, 18(1):89-92 | DOI: 10.26552/com.C.2016.1.89-92

The article presents preliminary fatigue tests results of two high-strength steels used in structural elements of trailers, wagons, farm devices, etc. Paper presents an analysis of fatigue test results of high-strength steels in the range from 104 to 107 numbers of cycles of applied load with a frequency of 40 Hz. Wöhler curve shows the results of the fatigue properties of steels Hardox 400 and Hardox 450, which are used in the construction of vehicles. Fatigue fractures were subjected to fractographic analysis in order to determine the mechanism of fatigue crack propagation.

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