Computer Science

Permanent URI for this collectionhttps://hdl.handle.net/10679/43

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Browsing by Subject "360° video"

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    Benchmarking the second edition of the omnidirectional media format standard
    (IEEE, 2022) Kara, Burak; Akçay, Mehmet Necmettin; Beğen, Ali Cengiz; Ahsan, S.; Curcio, I. D. D.; Kammachi-Sreedhar, K.; Aksu, E.; Computer Science; BEĞEN, Ali Cengiz; Kara, Burak; Akçay, Mehmet Necmettin
    Omnidirectional MediA Format (OMAF) is the first worldwide virtual reality (VR) standard to store and distribute immersive media, completed in 2019. Later, in 2021, the second edition of this standard (OMAF v2) was published. The second edition kept all the features defined in the first OMAF edition while introducing some new ones, such as overlays and multi-viewpoints. OMAF v2's Tile Index Segments that contain metadata to track fragment data per segment and quality levels create a bandwidth overhead. During the OMAF v2 standardization, multiple methods for the track fragment run representation were studied to deal with this overhead. This paper presents the implementation of one of these methods, the compressed box method using the DEFLATE algorithm (OMAF v2*). It also provides comprehensive test results of OMAF v1, OMAF v2 and OMAF v2∗ with various combinations of three tile grids (6x4, 8x6 and 12x8), three segment durations (300 ms, 900 ms and 3 s), two videos (RollerCoaster and Timelapse), two bitrate groups (each group with four different bitrates) and two HTTP versions (HTTP/1.1 and H2).
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    Head-motion-aware viewport margins for improving user experience in immersive video
    (ACM, 2022-01-10) Akçay, Mehmet Necmettin; Kara, Burak; Ahsan, S.; Beğen, Ali Cengiz; Curcio, I.; Aksu, E.; Computer Science; BEĞEN, Ali Cengiz
    Viewport-dependent delivery (VDD) is a technique to save network resources during the transmission of immersive videos. However, it results in a non-zero motion-to-high-quality delay (MTHQD), which is the delta time from the moment where the current viewport has at least one low-quality tile to when all the tiles in the new viewport are rendered in high quality. MTHQD is an important metric in the evaluation of the VDD systems. This paper improves an earlier concept called viewport margins by introducing head-motion awareness. The primary benefit of this improvement is the reduction (up to 64%) in the average MTHQD.