tsid or transport_stream_id [EtherGuide Glossary]
A tsid (also known as a transport_stream_id) 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
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.