Extended Data Services

Extended Data Services (now XDS, previously EDS), is an American standard classified under Electronic Industries Alliance standard CEA-608-E for the delivery of any ancillary data (metadata) to be sent with an analog television program, or any other NTSC video signal.

XDS is used by TV stations, TV networks, and TV program syndication distributors in the USA for several purposes.

Here are some of the most common uses of XDS:

The "autoclock" system delivers time data via an XDS "Time-of-Day Packet" for automatically setting the clock of newer TVs & VCRs sold in the USA. Most PBS stations provide this service.
Rudimentary program information which can be displayed on-screen, such as the name and remaining time of the program,
Station identification,
V-chip content ratings data.

XDS is also used by the American TV network ABC for their Network Alert System (NAS). NAS is a one-way communication system used by ABC to inform and alert their local affiliate stations across the USA of information regarding ABC's network programming (such as program timings & changes, news special report information, etc.), using a special decoder manufactured for ABC by EEG Enterprises , a manufacturer of related equipment for the TV broadcast industry such as closed captioning and general-purpose XDS encoders. The CBS Television Network uses a similar method to transmit three separate internal messaging services to stations: one for programming departments, one for master control operations, and one for newsrooms.

Many standard definition receivers produced by Dish Network encode XDS data into their output signal. Data encoded includes time of day, program name, program description, program time remaining, channel identification, and content rating. This data is obtained from the satellite service's EPG and replaces any data which may have been present when the signal was uplinked.

XDS uses the same line in the vertical blanking interval as closed captioning (NTSC line 21), and shares the available second video field bandwidth with the closed captioning channels CC3 and CC4, and with the text channels TXT3 and TXT4.

External links

Does anybody really know what time it is? - Faults & Failures October 2000 IEEE Spectrum - about some failures in the autoclock system in 2000

Broadcast video formats

Television

Analog

525 lines	System M NTSC NTSC-J PAL-M

625 lines	PAL System B System D System G System H System I System K PAL-N PALplus SECAM System B System D System G System K System L (SECAM-L)

Audio	BTSC (MTS) EIAJ NICAM SAP Sound-in-Syncs Zweikanalton (A2/IGR)

Hidden signals	Captioning CGMS-A EPG GCR PDC Teletext VBI VEIL VIT VITC WSS XDS

Historical	Pre-1940 Mechanical television 180-line 405-line System A 441-line 819-line MAC MUSE

Digital

Interlaced	SDTV 480i 576i HDTV 1080i

Progressive	LDTV 1seg 240p 288p EDTV 480p 576p HDTV 720p 1080p UHDTV 2160p 4320p

MPEG-2 standards	ATSC DVB ISDB DTMB DVB 3D-TV

MPEG-4 AVC standards	ATSC A/72 DMB DTMB DVB SBTVD 1seg

HEVC standards	ATSC 3.0

Audio	AC-3 (5.1) DTS MPEG-1 Audio Layer II MPEG Multichannel PCM LPCM AAC HE-AAC

Hidden signals	AFD Broadcast flag Captioning CPCM EPG Teletext

Technical issues

14:9 compromise Broadcast-safe Digital cinema (DCI) Display motion blur Moving image formats MPEG transport stream Reverse Standards Conversion Standards conversion Television transmitter Video on demand Video processing Widescreen signaling Templates (Analogue TV Topics)

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