It is commonplace to see mobile phones used to shoot video whilst held in a portrait configuration (long axis vertical), which results in aspect ratios such as 9:16, rather than the conventional 16:9. Nevertheless, the importance of user-generated content to broadcasters has created the need to handle and archive images with non-traditional aspect ratios.
This document contains a set of recommendations aimed at ensuring that the full resolution of a vertical aspect ratio image is preserved during archival, and that when 16:9 video is repurposed with a view to creating a different aspect ratio output, to easily allow the operator to correctly align the area of interest in the captured image.
A set of diagrams illustrates the most likely archival scenarios that will be encountered.
The EBU further suggests that:
- SDOs define file formats, essence containers and live interfaces independent of resolutions and aspect ratios, in the longer term, and to define metadata describing the region(s) of interest’s intended destination format (resolution, “shape” and orientation of the essence in the video file), ensuring the content being archived can be reused with no appreciable loss of quality, and define operating points for commonly used combinations.
- Product vendors, when developing or upgrading professional applications and infrastructure, to include options that can interpret codecs with user-defined operating points, enabling these operating points to be carried end-to-end through broadcast infrastructure and that future AI / automated systems (aspect ratio and area of interest algorithms) should be designed to consider the recommendations in this document when creating images in different formats.
- Users archive the 9:16 HD raster scaled down in the centre of a 16:9 HD raster without modification to the orientation, in circumstances where there is an operational constraint or the infrastructure is not available to preserve the 9:16 HD raster in accordance with the recommended methods in this document.
Key words: Archive, Vertical Video, 16:9, 9:16,1:1, Aspect Ratio.
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|1.0||2021, November||First version|