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Impact of resolution change on subjective QoE measurement of streaming video
Nevřelová, Monika ; Pokorný, Jiří (referee) ; Kováč, Dominik (advisor)
This thesis deals with the process of development of web application for subjective evaluation of streaming video. The thesis describes the adaptive streaming technique, streaming services and both subjective and objective evaluation of streaming video. Methods for measuring of subjective evaluation (namely laboratory method and crowdsourcing method) are described in more detail. A special web-based tool for subjective evaluation of streaming video was created with use of HTML, PHP and MySQL languages. To simulate the network changes, such as changes of the bandwidths, there´re created scenarios where the player selects the quality of the streamed video. The process of collecting data via Laboratory method and Crowdsourcing method is described in the thesis. Collected data are then analyzed.
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Laboratory of Quality of Service
Eltahir Ahmadon, Ahmed ; Kolka, Zdeněk (referee) ; Polívka, Michal (advisor)
The Bachelor's work, you are reading, deals with the issue of VoIP calling and measurement its quality. In the following paragraphs the discussion will be about the basics of networking protocols such as TCP, UPD, IP and SIP, after that a preliminary introduction to QoS issues - ways of measuring voice quality for instance MOS and E-Model. Importance of implementing QoS for VoIP, and QoS parameters used in the proposed services (will be called "mechanisms"), such as Best effort service, Integrated and Differentiated services. Based on these fundamentals points with designed laboratory for quality of service. The laboratory will be aimed at testing the quality of codecs with regard to bandwidth, jitter, delay and packet loss. The solution lies in the fact that, which codecs are actually suitable for the service.
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Measurement of data network quality parameters
Ripper, David ; Kováč, Dominik (referee) ; Zeman, Václav (advisor)
The aim of this thesis was studying and describing known methods for testing transmission parameters in data networks based on protocol stack TCP/IP. Firstly were individual transmission parameters specified and determined their impact on service quality. Another aim was to carry out a comparison of the different methodologies of measurement of transmission parameters, performed their qualifications on the basis of these findings and methodology for measuring service quality from the user's perspective was proposed. It was a web application where users measured basic transmission parameters, then the users judged videos according to the evaluation scale MOS (Mean Opinion Score) and with the help of these data was analysis, classification connection and impact of connection on MOS evaluation.
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Program for evaluating image quality using neural network
Šimíček, Pavel ; Kratochvíl, Tomáš (referee) ; Slanina, Martin (advisor)
This thesis studies the assessment of picture quality using the artificial neural network approach. In the first part, two main ways to evaluate the picture quality are described. It is the subjective assessment of picture quality, where a group of people watches the picture and evaluates its quality, and objective assessment which is based on mathematical relations. Calculation of structural similarity index (SSIM) is analyzed in detail. In the second part, the basis of neural networks is described. A neural network was created in Matlab, designed to simulate subjective assessment scores based on the SSIM index.
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Design of CMOS operational amplifiers
Němec, Tomáš ; Bajer, Arnošt (referee) ; Musil, Vladislav (advisor)
This work deals with issues of design and simulation of analog integrated circuit. The general aim is to design high-speed transconductance differentiating amplifier. The two stage operational – transconductance amplifier with compensation RC element is presented. This compensation method of zero nulling used prevents amplifier from oscillation.
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VoIP Quality Analyzer
Krajíček, Michal ; Žádník, Martin (referee) ; Tobola, Jiří (advisor)
This thesis deals with the quality of the IP telephony and its measuring using the netflow technology. It describes individual factors influencing the quality from sampling and quantization over the impairment caused by codecs to the degradation during network transfers. Next part focuses on models allowing to regard quality of IP telephony with emphasis to the E-model and R-factor. It shortly describes the netflow technology and the quality measuring connected with it. Practical part describes the principle of how the quality is measured by the netflow probe nProbe together with offer and implementation of application measuring the quality. The comparison with commercial application is presented and the results are discussed.
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Laboratory of Quality of Service
Eltahir Ahmadon, Ahmed ; Kolka, Zdeněk (referee) ; Polívka, Michal (advisor)
Abstrakt Bakalářská práce se zabývá problematiku IP telefonie, emulace sítě a kvalitou službou (QoS). Kapitol 2 pojednává o model TCP/IP a OSI, síťových protokolech (IP, TCP, UDP) a o protokolu SIP. Kapitole 3 se zabývá problematikou QoS, definicí QoS, QoS ve službách s reálným časem, parametry a způsoby změření kvality hlasu – subjektivními a objektivními testy. Na základě získaných poznatků byla navržena laboratoř kvality služby. Laboratoř je zaměřena na testování kodeků z hlediska kvality přenášeného zvuku, s ohledem na šířku pásma a ztrátovost paketů. Laboratoř kvality služby byla navržena tak, aby byly splněny požadavky na subjektivní testy uvedené v kapitole 3. 4. Návrh laboratoře Schéma navržené laboratoř je zachyceno na obr. 4.1. Návrh je složen ze čtyř hlavních částí – Dvou softwarových IP telefonů (XLite), síťového emulátoru (WANem Wide Area Network emulator), a SIP ústředny (3CX Phone System pro Windows od 3CX Ltd). Sestavování spojení prbíhá podle stejného schématu viz obr. 4.1. Oba koncové uzly jsou připojeny přes emulátor WANem. Počítač, na kterém je emulátor instalován má dvě síťová rozhraní. PC1, resp. PC2 s WANem tvoří lokální síť 1 (LAN1), resp. lokální síť 2 (LAN2). Pakety prochází z jednoho uzlu do druhého přes WANem. WANem emuluje chování skutečné WAN sítě, umožňuje provádět v laboratorním prostředí testy na síti s přesně definovanými parametry. Návrh celé laboratoře je virtualizován. Je využita platform VirtualBox od Oracle. Podrobně je návrh popsán v kapitolách 4.1 a 4.2. QoS měření Během měření byly dva parametry sítě proměnné, resp. přesně určené nastavením WANemu – šířka pásma a ztrátovost. Protože testování probíhalo v místnosti, ve které se nachází elektronická zařízení a jiné zdroje ruchů, byla metoda ACR daná doporučením ITU-T P.800 upravena viz kapitola 4.3.1 Testovanému subjektu byly testovací nahrávky přehrávány do sluchátek. Dle ITU-T Rec. P.800 doporučuje několik metod hodnocení kvality služby – MOSLQ, MOSLE, MOSLP, ACR a CCR. K praktickému ověření funkčnosti navržené laboratoře byla vybrána modifikována verze ACR (M-ACR). Použité náhravky obsahují tři věty, mezi něž jsou vloženy mezery (volný interval – bez zvuku). Výsledky subjektivních testů jsou shrnuty v tab. 4-1 až tab. 4-10. MOS byl vypočítán pomocí rovnice (3. 1), jehož výsledky shrnuty v tab. 4. 11. Závěr Navrhovaná laboratoř byla úspěšně otestována, návrh splnil očekávání. S využitím navržené laboratoře proběhly subjektivní testy kodeku G.711 na 10 osobách.
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Evaluation of service quality parameters in data networks
Gregor, Lukáš ; Zeman, Václav (referee) ; Novotný, Vít (advisor)
The bachelor thesis deals about the issues of IP networks. About technologies for ensuring the quality of services, that is necessary to implement in today’s IP networks, due to the large increase of data flows. The bachelor thesis is oriented especially on technologies IntServ, DiffServ, MPLS and requirements of different types of services to the qualitative parameters of data networks. The aim of practical part is to devise a laboratory exercise for measuring qualitative parameters of different services under various condition in the intermediate network. Emulation of network parameters is carried out using emulation tool WANem with GNU Linux core.
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Analysis of the dependence of communications services to the delay and QoS optimization
Schön, Martin ; Číka, Petr (referee) ; Hošek, Jiří (advisor)
This thesis discusses wireless network standards 802.11a/b/g/n. First part explains basic principles of networks and media access. Next the standard IEEE 802.11, general QoS parameters and their application in wireless networks, according to standard 802.11e are analyzed. Second part of the thesis verifies the acquired knowledge in simulating program Opnet - effects of the delay, jitter and packet loss on VoIP call are tested. In the last part of the thesis a network for video streaming has been designed. The video was streamed in different qualities and the influence of other network traffic (with and without the support of QoS) on the video streaming was tested.
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Impact of rebuffering events on subjective QoE measurement of streaming video
Hůrek, Marek ; Pokorný, Jiří (referee) ; Kováč, Dominik (advisor)
This bachelor thesis mainly deals with the creation of a web-tool for subjective evaluation of quality of video in initial and repeated video loading and buffering. The simulation of adaptive streaming, focused on buffering, is performed on the basis of scenarios created in the database that are randomly generated and implemented into the aforementioned web-tool. The theoretical part of this thesis is focused on the analyzation of different types of streaming, streaming services and QoE service (subjective and objective evaluation). Two basic methods for the subjective evaluation (laboratory method and crowdsourcing) are described in more detail. At the end there are analyzed data received from measurement. Results are put into graphs with a description of subjective evaluation MOS.
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