Programme Delivery Control
Encyclopedia
Programme delivery control (PDC) is specified by the standard
ETS 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 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. Effectively, the two systems do the same thing and most modern VCR
s and stand-alone DVD recorder
s work with both signals.
In digital TV (see Freeview+
), the feature Accurate Recording is based on the PDC specification.
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.
Standardization
Standardization is the process of developing and implementing technical standards.The goals of standardization can be to help with independence of single suppliers , compatibility, interoperability, safety, repeatability, or quality....
ETS 300 231, published by the European Telecommunications Standards Institute
European Telecommunications Standards Institute
The European Telecommunications Standards Institute is an independent, non-profit, standardization organization in the telecommunications industry in Europe, with worldwide projection...
(ETSI). This specifies the signals sent as hidden codes in the teletext
Teletext
Teletext is a television information retrieval service developed in the United Kingdom in the early 1970s. It offers a range of text-based information, typically including national, international and sporting news, weather and TV schedules...
service, indicating when transmission of a programme starts and finishes.
PDC 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. Effectively, the two systems do the same thing and most modern VCR
Videocassette recorder
The videocassette recorder , is a type of electro-mechanical device that uses removable videocassettes that contain magnetic tape for recording analog audio and analog video from broadcast television so that the images and sound can be played back at a more convenient time...
s and stand-alone DVD recorder
DVD recorder
A DVD recorder , is an optical disc recorder that uses Optical disc recording technologies to digitally record analog signal or digital signals onto blank writable DVD media...
s work with both signals.
In digital TV (see Freeview+
Freeview+
Freeview+ and Freeview+ HD is a consumer brand created in the UK by DTV Services Ltd to "raise consumer awareness and promote sales" of Freeview capable digital TV recorders otherwise known as personal video recorders...
), the feature Accurate Recording is based on the PDC specification.
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.
External links
Technical specifications and FAQ- ETSI standards
- "Everything you ever wanted to know about PDC"
- ETSI TS 102 323 V1.4.1 (2010-01), Chapter 11: "Accurate recording" and Annex A: "Example recorder behaviour"