to 'soun'.
            + The Media Information Box shall contain the Sound Media Header Box.
            + The codingname of the sample entry is 'Opus'.
                This specification does not define any encapsulation using MP4AudioSampleEntry with objectTypeIndication
                specified by the MPEG-4 Registration Authority (http://www.mp4ra.org/).
                See 4.3.1 Sample entry format to get the details about the sample entry.
            + The 'dOps' box is added to the sample entry to 