The Equirectangular format is a projection scheme used to map a 360-degree panoramic image or video so that it can be displayed on a flat 2D screen. This type of projection maps a 360-degree view onto a rectangle, with the x-axis representing the horizontal direction (360 degrees around the viewer) and the y-axis representing the vertical direction (180 degrees from pole to pole).
It is as if the inner surface of a sphere, on which a 360-degree scene is depicted, were projected outwards onto a surrounding rectangle. The resulting rectangle shows the complete panorama in a ratio of 2:1, which means that the width is twice as long as the height.
Equirectangular projections are often used in VR production because they can be recognized directly by most 360-degree players and VR headsets and converted into an immersive experience. Viewed without special software or a VR headset, the proportions appear distorted. In VR playback, however, the image is correctly converted into a spherical shape, giving the viewer the feeling of standing in the center of the panorama.
Professional video editing programs such as Premiere and DaVinci Resolve are able to process Equirect formats. These programs have special filters with which normal 2D graphics and text can be distorted according to the Equirect format in order to be displayed undistorted in 360°.
All common 360° cameras output films in this format.
Metadata in 360° video files
Metadata in 360° video files is essential to enable correct playback and interaction in VR platforms. They contain information about the video itself and how it should be projected. This data defines that the video is spherical and uses equirectangular projection, allowing video players to recognize how to map the video for an immersive experience. In addition, metadata can include details such as the resolution, frame rate, encoding type, as well as specific VR parameters such as the initial viewing angles or the type of stitching - i.e. how the individual video sections were stitched together to create a seamless panorama. Without the right metadata, a 360° video could be displayed as a flat image, which destroys immersion. Therefore, embedding and preserving metadata is a critical step in the post-production and distribution of 360° content.
This metadata can be written into the films by video editing software or by special software such as this shareware tool here are subsequently added to the Mp4.
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