Editing Programme Delivery Control

{{short description|Television standard to indicate start and end of programmes}}
{{about|PDC/StarText teletext programme listings||Startext (disambiguation)}}
[[File:Medion MD8910 - Siemens SDA 5650-8004.jpg|thumb|VPS / PDC-plus Decoder IC by [[Siemens]].]]
'''Programme delivery control''' ('''PDC''') is specified by the [[standardization|standard]] ETS 300 231 (ETSI EN 300 231), published by the [[European Telecommunications Standards Institute]] (ETSI). This specifies the signals sent as hidden codes in the [[teletext]] service, indicating when transmission of a programme starts and finishes.

PDC (also known as Enhanced Teletext Packet 8/30 Format 2) is often used together with StarText, enabling the user to select a programme to record using specially coded teletext programme listings. The combination of features is often called '''PDC/StarText'''.

In Germany and some other European countries, the older standard '''video programming system''' ('''VPS''') is in use also known as format 2. Effectively, the two systems do the same thing and most modern [[videocassette recorder|VCR]]s and stand-alone [[DVD recorder]]s work with both signals.

In digital TV (see [[Freeview+]]), the feature [[Accurate Recording]] (AR) that was based on the PDC specification for analogue recording devices is now used for a [[Digital Video Broadcasting|DVB]]-SI event based scheduling system. This was due to the BBC discontinuing the [[Ceefax]] service.

==PDC Packets==
PDC is transmitted once a second in special packets addressed as magazine 8 and text row 30. Since this row is not displayable it does not interfere with normal pages. Packet 8/30 has various formats specified by ETSI and PDC is format 2. Each packet 8/30 format 2 also has a label number and there can be up to four labels transmitted at a time. Each label contains the scheduled start time and date for a programme and flags to indicate the state. Each programme is assigned a label and in general a label will follow this sequence.
* PRF Set – Prepare for Record. This will tell a VCR to wake up and get ready. This happens about 40 seconds before the programme is active.
* PRF Clear – The VCR should be recording.
* RTI – Record Terminate/Interrupt – Tells the VCR to stop recording. This label is held for 30 seconds after the programme ends.

There are complicated rules for the case where a programme is interrupted by another one as in the case of a film with a break for news in the middle.

There is also a TIMER flag that indicates that there is no valid PDC and that the VCR should use its own timer.

==References==
{{Reflist}}

== External links ==
Technical specifications and FAQ
* [http://www.etsi.org ETSI standards]
* [http://www.etsi.org/deliver/etsi_en/300200_300299/300231/01.03.01_60/en_300231v010301p.pdf ETSI EN 300 231 V1.3.1 (2003–04)], Specification of the domestic video Programme Delivery Control system (PDC)
* [http://www.etsi.org/deliver/etsi_en/301700_301799/301775/01.02.01_60/en_301775v010201p.pdf ETSI EN 301 775 V1.2.1 (2003–05)], Specification for the carriage of Vertical Blanking Information (VBI) data in DVB bitstreams 
* [http://www.etsi.org/deliver/etsi_ts/102300_102399/102323/01.05.01_60/ts_102323v010501p.pdf ETSI TS 102 323 V1.5.1 (2012-01)], Chapter 11: "Accurate recording" and Annex A: "Example recorder behaviour"
* [http://www.itu.int/dms_pub/itu-r/opb/rep/R-REP-BT.1226-1990-PDF-E.pdf CHARACTERISTICS OF A PROGRAMME DELIVERY CONTROL (PDC) SYSTEM FOR VIDEO RECORDING (1990)]
* [https://625.uk.com/pdc/ "Everything you ever wanted to know about PDC"]
* [http://wiki.hummy.tv/wiki/Padding_versus_Accurate_Recording "Padding versus Accurate Recording"]
* [https://worldwide.espacenet.com/publicationDetails/biblio?locale=en_EP&CC=DE&NR=3313799 Original VPS invention (European Patent Office)] German and English

{{Video formats}}

[[Category:Television technology]]
[[Category:Teletext]]