f this field may be used in
                the ChannelLayout if any as described in 4.5.1.
            + samplesize:
                The samplesize field shall be set to 16.
            + samplerate:
                The samplerate field shall be set to 48000&lt&lt16.
            + OpusSpecificBox
                This box contains initializing information for the decoder as defined in 4.3.2.

        4.3.2 Opus Specific Box<a name="4.3.2"></a>
            Exactly one Opus Specific Box shall be present in ea