Patent ID: 7499631

Claim:
A method for converting a data stream in a first format into a data stream in a second format, wherein each said data stream includes data packs in which video data and audio data are stored and a control pack for use in a playback control of the data stream, wherein in the data stream in the first format, address information, which represents addresses of the data packs and which is not required while the data stream is played back, is present and associated with the data stream, and wherein in the data stream in the second format, address information, which represents addresses of the data packs and which is required while the data stream is played back, is stored in the control pack, the method comprising the steps of: acquiring the data stream in the first format and the associated address information thereof; generating a second control pack in the second format from a first control pack in the first format, the second control pack storing the address information acquired; and replacing the first control pack with the second control pack, thereby generating the data stream in the second format from the data stream in the first format, wherein the data stream in the first format is an arrangement of multiple data units, each of the data units including a plurality of data packs and the first control pack, and wherein the method further comprises the steps of: locating an extension field, which is included only in a first one of the data packs, in each of second and following data units; detecting a data length of a stuffing field, which is arranged after the extension field and in which the stuffing data is stored in advance; and determining whether or not the data length detected is a reference length or less, wherein the step of replacing is carried out if the data length is the reference length or less.