transport_stream_id or tsid [EtherGuide Glossary]

A transport_stream_id (also known as a tsid) is a 16-bit unsigned integer in an MPEG-2 transport stream that identifies the network origination source or transmiter, (or both) that provides a particular transport stream or transport streams.

The MPEG-2 standard leaves the issuance of actual transport_stream_ids to individual MPEG-2 "users". One such user is the Advanced Television Systems Committee (ATSC), another is Digital Video Broadcasting (DVB) and the Society of Cable and Telecommunications Engineers (SCTE) among others.

The MPEG-2 standard requires the transport_stream_id to be placed in the transport_stream_id field, which is located in the header of the Program Association Table (PAT).

A/65, the ATSC Program and System Information Protocol (PSIP) standard, requres the transport_stream_id to present in the header of the terrestrial and cable virtual channel table (TVCT/CVCT.)  In additiona, each virtual channel listed in an ATSC VCT includes a channel_TSID field.  Thus, a receiver can determine, by matching the transport_stream_id in the PAT and VCT header and channnel_TSID field the exact signal that is being tuned in.

In the ATSC "zone", terrestrial users -- broadcast stations -- are issued a transport_stream_ids by inational broadcast regulators.  Since transport_stream_ids serve as almost a digital station identifier, they are coordinated between nations in a manner that prevents any two different stations from having the same tsid.

Terrestrial tsids not only distinguish different transport streams (such as emanating from different television stations), they serve to establish when a particular station's signal is available from different transmitters.  In the ATSC zone, receivers are expected to note the characteristics (including physical channel number) when a tsid is "tuned in" so that that signal can be retuned at a later date or time.

This website provides an easy-to-use tool that enabled anyone (except competitors) to lookup the United States of Canadian television station associated with a particular transport_stream_id.

Glossary