Method and apparatus for encapsulating encoded media data in a media file

A device of reconstruction of an encoded media data bitstream from at least one media file, the device comprising a processor configured for:

• obtaining at least two subpicture bitstreams from the at least one media file, the at least two subpicture bitstreams respectively corresponding to encoded media data of a subpicture corresponding to a rectangular region of video data;
• obtaining, from the at least one media file, information for setting a decoding order of at least two subpictures corresponding to the at least two subpicture bitstreams;
• generating the encoded media data bitstream comprising reconstructed picture units based on picture units of the obtained at least two subpicture bitstreams and the obtained information,
• wherein generating the encoded media data bitstream includes:
• appending the picture units of the at least two subpicture bitstreams in the reconstructed picture units in the order determined based on the information for setting the decoding order of the at least two subpictures, the information for setting the decoding order of at least two subpictures includes ‘spor’ defined in ISO/IEC 14496-15 standard, and
• for each reconstructed picture unit, reordering a prefix Adaptation Parameter Set, APS, Network Adaptation Layer, NAL unit from a corresponding picture unit of the at least two subpicture bitstreams prior to a first Video Coding Layer, VCL, NAL unit in the reconstructed picture unit.