The embodiments relate to a method, including writing a first and a second media entity in a container file; creating a media presentation description (MPD) with a first and a second Representation; the Representations belonging to Adaptation Sets; the Representations being associated with the media entities of the container file; when one of the Representations belongs to a media entity which is a thumbnail to a viewpoint or a thumbnail to an overlay, the method includes writing in the MPD file an association/correspondence/grouping information of the said one Representation with another Representation belonging to a media entity which is a viewpoint or an overlay, correspondingly. The embodiments also relate to a method for parsing, and technical equipment for implementing the methods.