Method, device, and computer program for dynamically encapsulating media content data

Encapsulating media data comprising: identifying portion of media data (or set of items of information related to portion of media data), according to parameter which is independent of encapsulation; encapsulating portion of (or set of items of) media data as entities in media file, entities being grouped into set of entities associated with first indication representative of parameter; wherein media file comprises second indication signalling to client that set of entities is to be parsed only if client has knowledge about first indication. Corresponding parsing of encapsulated media data. Encapsulating media data, comprising metadata portion ('mdat' 320 and 340) associated with media data and media fragments ('moof' 310 and 330), comprising: obtaining first portion of media data ('trak' [track_ID = 1]), first portion organised into first set (SampleEntry 'xxxx') of one or more media tracks; encapsulating metadata describing one or more tracks (Sample 1 [track 1] ... Sample N [track 1]) of first set (SampleEntry 'xxxx') of one or more tracks in metadata ('mdat' 320) portion and encapsulating first portion of media data into one or more media fragments ('moof' 310); obtaining second portion of media data, second portion organised into second set (SampleEntry 'yyyy') of one or more media tracks (Sample N+1 [track 1] ... Sample N+M [track 1]... Sample N+M+1 [track 2] ... Sample N+M+Z [track 2]); if at least one track of second set (SampleEntry 'yyyy') is different from tracks of first set (SampleEntry 'xxxx'), encapsulating second portion of media data and metadata into one media fragment ('moof' 330). Corresponding parsing of encapsulated media data.