Page 41 - ITU Journal, ICT Discoveries, Volume 3, No. 1, June 2020 Special issue: The future of video and immersive media

ITU Journal: ICT Discoveries, Vol. 3(1), June 2020

Fig. 1 – Content flow process for an MPEG OMAF system [5].

the omnidirectional space and is used to guide the experience of the user. Typical examples of overlay
player to download and render the appropriate part include, but are not limited to, advertisements, logos,
of the media streams. The viewport defines the subtitles, thumbnails of a map, etc.
horizontal and vertical user field of view within the Some of the omnidirectional video use cases in
omnidirectional space.
1
which overlays could be used are the following .
The new OMAFv2 functionalities discussed in this I. Omnidirectional sports videos in which the
paper, namely overlays and multi-viewpoints, are background video consists of the live match
defined both in the ISOMBFF, where the storage that is being played, and the overlay is a
format syntax and semantics are described in detail, video of the scorecard.
and at DASH and MMT transport levels [5]. The II. Other use of overlay videos in the context of
mentioned new functionalities are purposely sports may include an omnidirectional
described in the following two sections without background video of the match and an
mentioning the ISOBMFF and DASH syntax and overlay video of the highlights package or
semantics details.
an overlay video of a commentary box and
interview places.
3. OVERLAYS IN THE MPEG OMAF III. Overlays could also be part of an immersive
STANDARD session about a museum where the
Overlays are conventionally used to provide background video covers the museum near
complementary information about the video scene a well-known monument, and the overlay
and enhance the overall user experience. Recent video tells about the historical facts of the
studies on the use of overlays in a VR application [20] monument.
have hinted that the presence of an overlay within an
omnidirectional video increases the immersion

1 It is noted that the list of use cases presented here is not
exhaustive and is limited only for briefness.

© International Telecommunication Union, 2020 19