Disclosed is a method performed by a system of a communications network. The method comprises encoding the first data stream and the second data stream, analyzing time data related to the first and second data stream, in order to determine a time relationship between the first and second data streams. The method comprises creating an offset file comprising the time relationship between the first and second data streams and transmitting the first data stream, the first time metadata, the second time metadata and the offset file. The method comprises receiving the first data stream, the first time metadata, the second time metadata and the offset file and streaming the first data stream. The method comprises determining a start time for the second data stream, obtaining the second data stream and streaming the second data stream, such that the first and second data streams and synchronized.