Video formati in kodeki

Selič, Patricija (author), Urbas, Raša (mentor), Učakar, Andrej (co-mentor)

Že od začetka razvoja digitalnega videa leta 1988 se vsako leto razvijajo novi video formati z izboljšano kakovostjo zapisa, manjšo velikostjo datoteke in načinom upodabljanja oz. predvajanja video vsebin. Za objavo na spletu, ogled na različnih mobilnih napravah ali zaslonih večje dimenzijskih televizij je potrebno video vsebine zapisati v različnih formatih. Danes stremimo k temu, da bi bile zajete vsebine videov čim bolj realistične, da kompresijski in interpolacijski mehanizmi formatov ne bi povzročali velikih izgub podatkov med samim zapisovanjem, da zapisi video datotek ne bi bili preveliki. V ta namen se v praksi uporabljajo različni t..i. kodeki, ki urejajo optimalne rezultate. V teoretičnem delu diplomske naloge so opisani osnovni pojmi, kot so formati in kodeki, predstavljene pa so tudi druge vsebine, ki so direktno povezane z zapisovanjem video vsebin. S pomočjo teoretičnega dela so bili postavljeni temelji eksperimentalnemu delu, ki so pomagali ovrednotiti namembnost različne vrste video kodekov, njihove prednosti in slabosti. Namen diplomskega dela je bil na praktičnem primeru ugotoviti, kako pravilno zajeti, urediti in izvoziti video zapis, določiti parametre, na katere je potrebno biti pozoren, da so rezultati čim bolj optimalni. Pri zapisu video vsebine so bile upoštevane različne spremenljivke, kot so npr. število sličic na sekundo (angl. frames per second; krajše fps), način kodiranja v odvisnosti od prepustnosti kanala (angl. bitrate), ločljivost zapisa in druge. Cilj diplomskega dela pa je bil najprej raziskati različne literaturne vire in narediti pregled ter izbor kodekov in formatov, ki bi bili najbolj primerni, jih opisati nato pa uporabiti na praktičnem primeru. Z izvedeno raziskavo smo ugotovili, da je med primerjanimi video kodeki splošno najbolj uporaben kodek H.264/AVC. Ta je ustrezen tako za objave video vsebin na upodobitvenih kanali YouTube in Instagram, čeprav moramo pri slednjem paziti tudi na razmerje formata stranic, ki je omejeno. Ugotovili smo, da smo pri pošiljanju video vsebin najmanj omejeni pri e-pošti.

• Language: Slovenian
• Keywords: kodek, kompresija, format, video
• Work type: Bachelor thesis/paper
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Year: 2019
• PID: 20.500.12556/RUL-109701
• Publication date in RUL: 07.09.2019

Secondary language

• Language: English
• Title: Video formats and codecs

Abstract

Since digital video development began in 1988, new video formats are developed each year with the improved recording quality, smaller file size, and rendering mode. In order to post videos online, and enable viewing on various mobile devices or screens of larger dimensions, video content must be recorded in different formats. Today, we strive to make video content as realistic as possible, so that compression and interpolation mechanisms of formats do not cause significant data loss during the formatting, and that they would not be too large within such video format. That is why there are codecs that regulate optimal results. The theoretical part of this thesis describes the basic concepts, such as formats and codecs, and other contents that are directly related to the recording of video. The theoretical part was then utilised in the creation of the foundation for experimental work, which helped to evaluate the purpose of various types of video codecs, their advantages, and disadvantages. The aim was to determine how to adequately capture, edit and export the video, as well as how to determine the parameters that need to be considered so that the results are as optimal as possible. When recording video content, several variables were considered: the number of frames per second, the encoding mode in dependence on bitrate, and others. The experimental part of the thesis shows that the most useful codec among compared codecs is H.264 / AVC. This codec is also best used for YouTube videos and Instagram posts, but the limited nature of the ratio must be kept in mind. The minimum limit is when sending files through e-mail. The purpose of this thesis is to showcase how to adequately capture, edit and export video, and determine the parameters that need to be considered through practical experimentation to achieve the most optimal results. When recording video content different variables, such as the number of frames per second (fps), the encoding mode in dependence on the channel permeability (bitrate), and resolution, were considered. The goal of this thesis was to determine the differences between codecs on the practical case and which codec is most suitable for a particular purpose. Firstly, academic research of various literature sources was conducted through which an overview and selection of codecs and formats that would be best suited to describe them. Then, this information was used in practical examples and to describe the changes and to present them as clearly as possible.

• Keywords: format, codec, compression, video