Modern pitch-shifting algorithms and its aplication in virtual musical instruments

Cílem diplomové práce je seznámení s metodami posunu základního tónu akustických signálů. Teoretická část práce obsahuje popis tří různých technik pro posun základního tónu, je to metoda s využitím modulace zpožďovací linky, metoda PICOLA a metoda s využitím fázového vokodéru. První dvě metody jsou zástupci zpracování v časové doméně, třetí metoda představuje zpracování v kmitočtové oblasti. V souvislosti s metodou PICOLA jsou v práci také zmíněny algoritmy pro odhad základní periody signálu. V závěru teoretické části jsou metody srovnány z různých hledisek. Praktická část demonstruje využití těchto metod. Je zde popsán virtuální hudební nástroj sampler založený na přehrávání zvuků uložených v paměti. V této části jsou popsány jednotlivé funkční celky zajišťující požadovanou činnost sampleru. Generování zvuků virtuálního nástroje je řízeno pomocí MIDI protokolu. Pro generování různých tónů z jednoho uloženého zvuku je použita metoda PICOLA.This diploma thesis deals with pitch shifting methods of acoustical signals. The theoretic part of this thesis involves description of three different pitch shifting techniques, these are the method using a modulated delay line, PICOLA method and method using a phase vocoder. The first two methods represent the processing in time domain, the third method represents the processing in frequency domain. In relation with the PICOLA method, the thesis also mentions algorithms for pitch estimation. The practical part demonstrates the use of these methods. There is described a sampler virtual musical instrument based on the playback of the sounds stored in memory. In this part the particular units providing the required functionality are described. The generating of sounds is controlled by the MIDI protocol. In the sampler is implemented the PICOLA method.

Automation of Exoscopic Analysis Using Image Processing of Sedimentary Grains Acquired by Electron Microscope

This thesis deals with image analysis methods which can be exploited in exoscopic analysis of sedimentary grains, specifically for the purpose of distinguishing between geomorphologic geneses which influenced a form of sedimentary grains. The images of sedimentary grains were acquired by a scanning electron microscope. The main contribution is the proposal of multiple methods that can significantly automate the exoscopic analysis. These methods cover the automatic segmentation of grains in image, the automatic analysis of roundness of 2D grain projection and the classification of geomorphologic geneses according to the grain surface structure. In the section concerning the automatic segmentation, a segmentation method enabling an easy subsequent manual result correction was proposed. This method is based on the split-and-merge approach. The individual steps the procedure were designed to exploit specific properties of sedimentary grain images in order to obtain the best segmentation results. In the section concerning the automatic roundness analysis of 2D projection of sedimentary grains, an influence of pixel resolution on a result roundness value was evaluated. Further, a minimal number of grains, which is necessary to analyze in order to reliably compare a pair of geomorphological geneses, was investigated. For the determination of this number, a method was proposed and experimentally verified. In the section of automatic analysis of sedimentary grain surface structure, a method for classification of geomorphologic geneses was proposed. The method utilizes low-level texture features which describes individual images of sedimentary grains. A model of geomorphological genesis is constituted of a set of histograms representing occurrences of different configurations of low-level texture features. The methods proposed in the thesis were tested and evaluated based on a database, which consists of sedimentary grain samples from 4 different geomorphological geneses (eolic, glacial, slope and volcanic)

Automation of Exoscopic Analysis Using Image Processing of Sedimentary Grains Acquired by Electron Microscope

This thesis deals with image analysis methods which can be exploited in exoscopic analysis of sedimentary grains, specifically for the purpose of distinguishing between geomorphologic geneses which influenced a form of sedimentary grains. The images of sedimentary grains were acquired by a scanning electron microscope. The main contribution is the proposal of multiple methods that can significantly automate the exoscopic analysis. These methods cover the automatic segmentation of grains in image, the automatic analysis of roundness of 2D grain projection and the classification of geomorphologic geneses according to the grain surface structure. In the section concerning the automatic segmentation, a segmentation method enabling an easy subsequent manual result correction was proposed. This method is based on the split-and-merge approach. The individual steps the procedure were designed to exploit specific properties of sedimentary grain images in order to obtain the best segmentation results. In the section concerning the automatic roundness analysis of 2D projection of sedimentary grains, an influence of pixel resolution on a result roundness value was evaluated. Further, a minimal number of grains, which is necessary to analyze in order to reliably compare a pair of geomorphological geneses, was investigated. For the determination of this number, a method was proposed and experimentally verified. In the section of automatic analysis of sedimentary grain surface structure, a method for classification of geomorphologic geneses was proposed. The method utilizes low-level texture features which describes individual images of sedimentary grains. A model of geomorphological genesis is constituted of a set of histograms representing occurrences of different configurations of low-level texture features. The methods proposed in the thesis were tested and evaluated based on a database, which consists of sedimentary grain samples from 4 different geomorphological geneses (eolic, glacial, slope and volcanic)

Implementation of digital metronome with oversampling in VST technology

Tato bakalářská práce je vypracováním požadavku na implementaci digitálního metronomu v technologii VST. V úvodu jsou rozebrány základní vlastnosti digitálního metronomu a na jejich základě je navržen algoritmus, jenž bude digitální metronom realizovat. Tento algoritmus je zapouzdřen do třídy C++ s patřičně definovaným rozhraním, která je tak vhodná pro využití v různých technologiích pro zpracování digitálního zvukového signálu. Takto zapouzdřený metronom je implementován v technologii VST ve formě plug-in modulu. Pro tyto účely je v práci stručné seznámení s vývojovou sadou VST, definicemi jejích základních metod a způsobem, jakým lze pomocí ní vytvořit vlastní grafické uživatelské rozhraní VST plug-in modulu. Pro realizaci funkce volby libovolného zvuku jeho načtením ze souboru typu wav je v práci popsán formát RIFF, jež specifikuje formát ukládání multimediálních dat do souborů na disk. Na základě znalosti tohoto formátu je funkce načítání z wav souboru implementována. Pro potřebu přizpůsobení vzorkovací frekvence načteného zvuku je v práci pojednáno o problematice převzorkování a následně tyto poznatky využity při implementaci funkce převzorkování.This bachelor’s thesis presents solution to requirement of implementation of digital metronome in VST technology. In the beginning, there is analysis of basic characteristics of digital metronome, that helps to suggest algorithm realizing digital metronome. Algorithm is encapsulated into C++ class with appropriate interface, which is suitable for usage in different technologies of digital sound signal processing. This way encapsulated metronome is implemented in VST technology as plug-in. For this reason, thesis contains a brief introduction to VST software development kit, definitions of its basic methods and way how to do graphical user interface of VST plug-in. For realizing of function enabling choice of any sound loaded from wav file, there is a description of RIFF format, that specifies the format of saving multimedia data into drive. Using this knowledge, the function of loading from wav file is implemented. In order to adjust sampling frequency of loaded sound, thesis deals with problems of sample rate conversion and implements resampling function.