A Tool for Tracking RTP Streams

Tento dokument popisuje vývoj algoritmu a testovací aplikace pro detekci RTP streamů v počítačových sítích. Jedním z výsledků bude nástroj v jazyce Python rozpoznávající RTP streamy v datech odchytávaných ze síťového rozhraní v reálném čase, nebo z dat uložených ve formátu pcap.This document describes the development of the algorithm and test application for detection of RTP streams in computer networks. One of the results will be a tool in Python language recognising RTP streams in data filtered from network interface in real time or from the data in pcap format.

On-line monitoring of VoIP quality using IPFIX

The main goal of VoIP services is to provide a reliable and high-quality voice transmission over packet networks. In order to prove the quality of VoIP transmission, several approaches were designed. In our approach, we are concerned about on-line monitoring of RTP and RTCP traffic. Based on these data, we are able to compute main VoIP quality metrics including jitter, delay, packet loss, and finally R-factor and MOS values. This technique of VoIP quality measuring can be directly incorporated into IPFIX monitoring framework where an IPFIX probe analyses RTP/RTCP packets, computes VoIP quality metrics, and adds these metrics into extended IPFIX flow records. Then, these extended data are stored in a central IPFIX monitoring system called collector where can be used for monitoring purposes. This paper presents a functional implementation of IPFIX plugin for VoIP quality measurement and compares the results with results obtained by other tools

Analysis and Detection of Multimedia Types in RTP Traffic

Tato práce se věnuje problematice detekce kodeku použitého při kódování hlasových dat nesených protokolem RTP bez dostupnosti informací nesených signalizačními protokoly ve VoIP aplikacích. Jejím hlavním cílem je navrhnout a implementovat rychlý algoritmus na detekci kodeků používaných pro přenos hlasu protokolem RTP. Tento algoritmus by měl být dostatečně rychlý pro použití jak na off-line analýzu zachycených dat, tak na on-line analýzu v reálném čase. Pro průzkum možností byly porovnány dva přístupy detekce. Pro samotné řešení problému byla zvolená detekce pomocí charakteristických znaků kodeku. V rámci řešení byla provedena analýza dat, implementace aplikace a následné testování na datech.This thesis deals with the issues of detecting the codec used for the encoding of voice data carried by the RTP protocol without having access to the information carried by signalisation protocols in VoIP applications. Its main goal is to create and implement a fast algorithm for detecting the codec used for voice transfer via the RTP protocol. This algorithm should be fast enough to be used for offline analysis of captured data as well as for real-time online analysis. For research of possibilities were compared two approaches of detection. Detection by the characteristics of the codecs was chosen to solve the problem itself. Within the solution was performed data analysis and implementation of the application followed by testing on data.

Characterisation of Lactobacilli from eweʼs and goatʼs milk for their further processing re-utilisation

Raw ewe's and goat's milk is a good source for isolation of wild lactobacilli which are able to bring unique processing properties in development of dairy products - cheeses or fermented dairy products. 34 strains of lactobacilli were isolated, purified and identified from fermented ewe's and goat's dairy products. These products were processed without thermal treatment and without using of any commercial starters. After preliminary selection, the final collection of 5 strains was established. The strains were identified as:<em> Lbc. plantarum</em> (2), <em>Lbc. paraplantarum</em> (1), <em>Lbc. paracasei</em> (1) and <em>Lbc. johnsonii</em> (1). Except two strains, all were able to coagulate milk. After hydrolysis of lactose in milk, two strains were able to form sensorial attractive coagulate too. All of the strains were homofermentative, they produced lactic acid but they did not produce CO2. Their ability to produce diacetyl was low. They did not show strong proteolytic activity. All strains grew at 30 &deg;C and 37 &deg;C, however <em>Lbc. johnsonii</em> much slower at 30 &deg;C than the others. Except <em>Lbc. johnsonii</em>, all strains tolerated 2% concentration of NaCl and even in presence of 5% concentration of NaCl their growth was inhibited only moderately. All of characterized strains can be provisionally used as starter or starter adjuncts in dairy technology, during production of cheeses or fermented milk products from pasteurised milk. These results will be used in further processing studies of isolated strains and will be supplemented with other properties e.g. safety, probiotic and antimicrobial properties.<br /