cedure of the assignment is the following.

                1. Decoded channels are mapped to output channels according to the ChannelMappingTable.
                2. Output channels are mapped to loudspeaker positions according to the ChannelLayout.

            In this way, the parameters of the Opus Specific Box are processed before the ChannelLayout, and the
            ChannelLayout shall follow the Opus Specific Box.

        4.5.2 Composition on all active tracks (informative)<a name="4.5.2"></a>
   