Primerjalna analiza vpliva izbranih kodekov na zapis video vsebin

Strgar, Matic (author), Urbas, Raša (mentor), Učakar, Andrej (co-mentor)

Video vsebine so vedno bolj popularen medij komunikacije in vedno več ljudi se ukvarja s snemanjem in montažo. Z vsem tem je močno porasla količina video vsebin, ki se dnevno delijo na družabnih omrežjih in platformah, kot so YouTube, TikTok, Vimeo ter druge. Da je vse to mogoče, pa poskrbijo kodeki, ki video posnetke stiskajo in omogočajo, da si jih lahko brez večjih težav ogledujemo na napravah. Razumevanje kodekov v praksi je žal še vedno precej slabo in v ta namen je nastala raziskava tega magistrskega dela. Z raziskavo so bile določene smernice, ki bi ustvarjalcem video vsebin nekoliko olajšale razumevanje kodekov in načinov vpliva različnih dejavnikov in odločitev, sprejetih pri postopkih zajema na končno kakovost upodobljenega video posnetka. V raziskavi se je analiziral vpliv količine gibanja, bitne globine, bitne hitrosti, števila sličic na sekundo, ločljivosti video posnetka, snemanja v načinu stiskanja posamezne sličice v primerjavi s snemanjem v načinu stiskanja čez več sličic in vpliva količine šuma, prisotnega v video posnetku, na končno kakovost posnetka. Pri tem se je analizirala učinkovitost stiskanja treh najpogosteje uporabljenih kodekov: MPEG-2, H.264 in H.265, z objektivno analizo kakovosti videa in z vizualno analizo izbranega detajla. Za objektivno analizo se je uporabilo rezultate metrik PSNR, SSIM, VMAF in EPSNR in z dobljenimi rezultati ugotavljalo vpliv posameznega parametra na končno kakovost stisnjenega video posnetka. V rezultatih je predstavljeno, kako posamezen parameter vpliva na stiskanje s posameznim kodekom in iz tega definiranih kar nekaj smernic, ki bodo lahko v pomoč ustvarjalcem video vsebin pri razumevanju kodekov in njihovega delovanja.

• Language: Slovenian
• Keywords: bitna globina, bitna hitrost, H.264, H.265, kodek, stiskanje, ločljivost, MPEG-2, velikost datotek, video
• Work type: Master's thesis/paper
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Year: 2021
• PID: 20.500.12556/RUL-129697
• Publication date in RUL: 07.09.2021

Secondary language

• Language: English
• Title: Comparative analysis of impact of selected codecs on video content rendering

Abstract

Video content is an increasingly popular medium of communication, and more and more people are engaging in video recording and editing. As a result, the amount of video content shared daily on social media and platforms such as YouTube, TikTok, Vimeo, and others has greatly increased. This is made possible by codecs that compress videos and allow them to be viewed on our devices without major issues. Unfortunately, the understanding of codecs in practice is still quite poor, which is why a research of this master thesis was conducted. The aim of the research was to create guidelines that would make it a little easier for video creators to understand codecs and the way in which the various factors and decisions made in the recording process affect the final quality of the video presented. This study analysed the effect of motion amount, bit depth, bitrate, frames per second, video resolution, single frame compression recording versus multi-frame compression recording, and the effect of noise on the final video image quality. Efficiency of the three most commonly used codecs: MPEG-2, H.264 and H.265, was analysed by objective analysis of video quality and by visual analysis of selected details. For the objective analysis the results of PSNR, SSIM, VMAF and EPSNR matrices were used, and with the obtained results the influence of each parameter on the final video compression quality was determined. Obtained results clearly showed how each parameter affects the compression with each codec, and from this some guidelines were defined to help video producers to better understand the codecs and how they work.

• Keywords: bitrate, codec, bit depth, compression, file size, H.264, H.265, MPEG-2, resolution, video