Aspects of the disclosure provide a method and an apparatus for deriving composite tracks. The disclosed apparatus includes a processing circuitry. The processing circuitry is configured to generate a file that includes elementary track boxes respectively for elementary tracks. The elementary track box indexes a sequence of media samples in a time order that forms an elementary track. The processing circuitry is configured to construct a composite track box for a composite track. The composite track box identifies one or more elementary tracks, and a composite operation to form the composite track based on the one or more elementary tracks. The processing circuitry is further configured to generate a media presentation based on the composite track.