There are provided a device and a method for generating timed media data, the timed media data comprising samples, the method comprising:



obtaining samples of the time media data;
creating tracks each comprising at least one of the obtained samples; and generating a presentation file comprising descriptive metadata associated with the created tracks,
wherein the descriptive metadata comprise at least one track group box describing at least one group of created tracks, all the tracks belonging to a same group sharing properties,
wherein a list of existing groups of tracks is declared in one single location in the presentation file, and
wherein the properties shared by the tracks of a group of the list are declared at the same single location in the presentation file.