'stpp': just checked the latest ISOBMF draft: only namespace is mantatory, xml_schema_loc and mimes are optional
'stpp': just checked the latest ISOBMF draft: only namespace is mantatory, xml_schema_loc and mimes are optional
DmitrySigaev/gpac-sf,DmitrySigaev/gpac-sf,DmitrySigaev/gpac-sf,DmitrySigaev/gpac-sf,DmitrySigaev/gpac-sf,DmitrySigaev/gpac-sf