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Subjective assessment of disturbing noise from gramophone records
Vlašín, Martin ; Martinásek, Zdeněk (referee) ; Rášo, Ondřej (advisor)
The bachelor thesis is focused on distortion that occurs by playing gramophone records. Due to functional principle of turntable and due to origin of individual distortion, which may occur while playing records, were selected two most significant and most frequently occurring distortion. For these distortion is studied their effect on subjective assessment of audio record. From data obtained from participants in the listening test was performed statistical analysis, also test of reliability and detection of any possible errors occurring in the assessments of individual listeners. The conclusions from results confirmed differences between two distortions and also between different audio samples on the subjective perception of the quality of audio experience for listener.
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Restoration of analog sound records form magnetic tapes
Spiššák, Filip ; Vrba, Kamil (referee) ; Rášo, Ondřej (advisor)
The aim of this bachelor thesis is a theoretical analysis of noises that often occur in magnetic audio tape recordings both from objective and subjective point of view. Furthermore, listening test is designed and carried out. In this test, the task of the listener is to evaluate the subjective variable „disturbance rate of unwanted sound in audio recording“ via specific software that was designed for this purpose. From the described noises, unwanted sounds represent the three most frequently occuring ones. It is a so-called „Hiss“ and two variations of „Hum“ noises. Hum is investigated in two dimensions so that the differences in the perception of even and odd harmonics can be analysed. Through a statistical analysis of the collected data, these noises can be classified according to the subjective perception of the specific recordings, which was also the primary purpose of this work. The findings of this thesis indicate that for instance Hiss is the most disturbing noise and that there is not a significant difference in the perception of even and odd harmonics. This information could be useful for the purposes of old record’s restorations, for example when an effort is made to remove specific types of noise. The measurement performed in this work may also help with the planning of other time-consuming and money-consuming listening tests.
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Modular web interface for Asterisk PBX
Moučka, Martin ; Rášo, Ondřej (referee) ; Krajsa, Ondřej (advisor)
This bachelor thesis is dealing with various ways of configuring Asterisk PBX and creating a modular web interface. This interface’s goal is to simplify the configuration of PBX and allow expanding its functions by adding new modules. Apart from a simple configuration, interface contains a self care zone where user can check his call history and keep his own phone book. As part of this work, there are two modules especially useful in environment of technical support and call centers. Those modules provide an opportunity to create interactive voice response menu, calling automat and queues management. Interface depends on Asterisk in version 13 which is the newest version with long term support. The application is secured by user account management with role assigning. The role can be modified by permitting only specified actions.
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Subjective evaluation of background noise in audio systems
Falešník, Vlastimil ; Mach, Václav (referee) ; Rášo, Ondřej (advisor)
In this bachelor thesis, the effect of additive background noise on audio recordings was researched. This kind of noise often occurs when these recordings are being restored. The most frequent effort is to suppress these unwanted noises. While suppressing the noises, the most problematic part is that it always depends on subjective evaluation of the listener. Practical impacts of these noises were researched throughout two listening tests. Afterwards, it was necessary to choose proper (ordinal) evaluating scale. The listening tests established the subjective assessment of jammed additive noise degree. Finally, the effect of selected parameters on subjective perceived quality was determined.
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Neural networks in cryptography
Borkovec, Tomáš ; Rášo, Ondřej (referee) ; Martinásek, Zdeněk (advisor)
Bachelor's thesis aims to introduce neural networks and their properties, which can be used for creating cryptographic protocols based on neural networks. It proposed concrete use of neural networks in cryptography and creates a teoretical basis for the practical implementation. In practical section is discusses the creation of neural network on which we based cryptographic model. The constructed models are then subjected to testing. At the close of the thesis we discussed the advantages and disadvantages of possible use in real cryptographic modules.
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Making up missing audio signal sections
Pospíšil, Jiří ; Rášo, Ondřej (referee) ; Mach, Václav (advisor)
The goal of this bachelor’s thesis is to get introduced with methods for reconstruction of missing samples in audio signal using periodicity-based interpolation and AR model based interpolation. Further it’s introducing us with Audio Inpainting method based on sparse representation. In practical part there are programmed three algorithms based on these interpolation methods and described an algorithm which is used in Audio Inpainting. These algorithms are compared with objective methods, SNR measurements depending on gap length and value of input parameter.
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Power-line network communication
Sláčik, Ján ; Rášo, Ondřej (referee) ; Kolka, Zdeněk (advisor)
The master’s thesis is dealing with PLC technology and its modem realization based on several types of standards by using commercially available integrated circuits. This projects also describes fundamentals and prerequisites for building the PLC network fulfilling the European standard CENELEC. The work further describes designed system concept, which serves as the automated system for the appliances connected to an electrical network. Components are selected for implementation and then is introduced concrete solution and implementation power-line network. Within the work are then other parts, that together form a system concept. Work includes the hardware and software implementation and a description of the options implemented system.
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Hierarchical Coding of Moving Pictures
Špaček, Milan ; Rášo, Ondřej (referee) ; Schimmel, Jiří (advisor)
Bachelor‘s thesis deals with hierarchical coding – scaling – of moving pictures in currently widely used compression algorithms MPEG-2 and MPEG-4. Scaling is the process whereby the encoded data stream is divided into graduated layers, adapted especially to the possibilities of transmission media and capabilities of terminal devices. The content of the base layer is a signal with reduced quality. The content of one or more extension layers is a supplementary picture information, completing the signal to a full quality form. The decoder, depending on its abilities and external circumstances, can decode only the relevant layers from the received bitstream. The thesis focuses in the theoretical part on the detailed description of encoding and decoding video signal according to MPEG standards using three types of scalability. In the concrete, the spatial, qualitative SNR and Fine granular scalability are mentioned. In the practical part of thesis was created an educational application in Matlab environment with its own graphical user interface, which implements the functions performing spatial, qualitative SNR and Fine granular scalability. Based on the user-specified input parameters, it performs scaling the image and then displays the outputs of individual layers after scaling and after the image reconstruction. The input of the programme, in which a hierarchical coding is done, is the image in bitmap format with any size in RGB format.
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