Methods, apparatus and systems for signaling preselections

A method of processing a media stream, comprising:

• receiving the media stream packetized in accordance with ISOBMFF format, wherein the media stream comprises one or more track boxes referencing respective tracks indicative of media components of the media stream;
• determining whether the media stream comprises a preselection-related box of predefined type indicative of a preselection, wherein the preselection corresponds to a media presentation to a user;
• if it is determined that the media stream comprises the preselection-related box:
• analyzing metadata information corresponding to the preselection-related box, the metadata information being indicative of characteristics of the preselection;
• identifying one or more tracks in the packetized media stream contributing to the preselection based on the metadata information;
• and
• providing the one or more tracks for downstream processing in accordance with the preselection.

A method of processing a media stream, comprising:

• receiving the media stream packetized in accordance with ISOBMFF, wherein the packetized media stream comprises a plurality of hierarchical boxes each being associated with a respective box type identifier, wherein the plurality of boxes comprise one or more track boxes referencing respective tracks indicative of media components of the media stream and one or more track group boxes each being associated with a respective pair of a track group identifier and a track group type that jointly identify a respective track group within the media stream, wherein tracks having the same track group identifier and the same track group type belong to the same track group;
• and wherein each such track group determines a preselection corresponding to a media presentation to a user;
• checking the track boxes in the media stream to determine a full set of preselections that are present in the media stream, wherein the determination of the full set of preselections comprises:
• determining a set of unique pairs of track group identifiers and track group types, and addressing the preselections by respective track group identifiers;
• selecting a preselection among the full set of preselections, wherein the preselection is selected based on attributes of the respective preselection that are included in track group boxes with the same track group identifier;
• determining a set of one or more track boxes contributing to the selected preselection based on a track group box with the same track group identifier;
• determining, as one or more tracks contributing to the preselection, tracks that are referenced in each member of the set of one or more track boxes;
• and
• providing the one or more tracks for downstream processing in accordance with the preselection.