1 Sample entry format<a name="4.3.1"></a>
            For any track containing Opus bitstreams, at least one sample entry describing corresponding Opus bitstream
            shall be present inside the Sample Table Box. This version of the specification defines only one sample
            entry format named OpusSampleEntry whose codingname is 'Opus'. This sample entry includes exactly one Opus
            Specific Box defined in 4.3.2 as a mandatory box and indicates that Opus samples described by this samp