          [ftyp: File Type Box]
                position = 0
                size = 24
                major_brand = Opus : Opus audio coding
                minor_version = 0
                compatible_brands
                    brand[0] = Opus : Opus audio coding
                    brand[1] = iso2 : ISO Base Media file format version 2
            [moov: Movie Box]
                position = 24
                size = 757
                [mvhd: Movie Header Box]
                    position = 32
         