Method and a computer program product for modifying or generating a multiple program transport stream

Methods and computer program products for modifying a multiple program transport stream, generating a multiple program transport stream and extracting a single program transport stream, the method for modifying the multiple program transport stream includes: receiving a multiple program transport stream; and inserting a decoding time stamp equivalent value program clock reference in a transport stream packet of a program; wherein the transport stream packet is positioned so as the value of the inserted decoding time stamp equivalent value program clock reference is substantially equal to a decoding time stamp of an elementary stream of the program.