Video programming system

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VPS / PDC decoder IC from Siemens

The Video Programming System ( VPS ) [ ˌvɪdioʊ ˈproʊgɹæmɪŋ ˌsɪstəm ] is used by video recorders to react to postponements of the start time, broadcast failures and overdrafts of the planned broadcast duration when recording programs. It is based on a signal that some television stations transmit in the blanking interval (more precisely in video line 16) of the television signal. The signal was first broadcast in Germany in 1985 by ARD .

The system transmits the VPS time indicated in teletext and in TV magazines for the duration of the program or contribution . The video recorder compares the start time programmed by the user with the VPS time specification: If both times match, recording will start. The recording continues as long as the sent VPS time and the programmed start time match.

Programs newly included in the daily program are usually given a VPS time one minute before the broadcast starts, so that there is no collision with the canceled / postponed program.

With the digital distribution via DVB, the VPS signal could no longer be used (for a certain time). For this reason, a VPS-like digital signal was developed with Program Delivery Control (PDC), which is sent in the form of additional data via the DVB service information. In the meantime, German public broadcasters also offer this digital recording control signal.

VPS has nothing to do with ShowView . Both are independent systems that complement each other. ShowView was developed to simplify the timer programming of video recorders and works even if no VPS data is transmitted from the transmitter. VPS, on the other hand, controls a recording that has already been programmed (with or without ShowView).

Technical details

The VPS data is transmitted continuously. 15 bytes are reserved for this in the vertical blanking interval of line 16 of each frame (corresponds to a transmission cycle of 40 ms):

Byte no. Function / use
1 run in Synchronization of the clock generator on the receiver side
2 Start code is to recognize the data line
3 and 4 Source detection to identify the program source
5 Sound data, special identification Information about the type of sound transmission,
for example: identifier for a broadcast that is not suitable for minors
6-10 Content identification and signals for internal control tasks
11-14 VPS label Signals for controlling video recorders
15th reserve

Structure of the 32 bit (byte 11 to 14) large VPS label:

  • 2 bit: Identification of the address area
  • 5 bit: announced broadcast day
  • 4 bit: announced sending month
  • 5 bit: announced start of contribution, hour
  • 6 bit: announced start of contribution, minute
  • 4 bit: nationality code
  • 6 bit: program source code (transmitter code)

In addition, three system codes are provided:

  • System status code (broadcast if there is no VPS label and the video recorder is to work in timer mode)
  • Interruption code (broadcast in the event of intentional and unintentional program interruptions, such as advertising or inserted news during a long sports program; is regularly used for commercial breaks on ARD and ZDF in the evening program)
  • Empty code (broadcast not for the recording of certain contributions, e.g. test images)

Practical advice

Private broadcasters in particular pay little attention to correct VPS encoding, so it is risky for the user to rely on VPS for recording programming. This can also be seen in the fact that many stations without VPS (e.g. RTL , Pro7 ) transmit the VPS carrier signal for no reason, so that many video recorders incorrectly recognize these stations as VPS providers. Only with the public broadcasters does VPS function reasonably reliably today (2009) in Germany. With digital reception (DVB-T, DVB-S, DVB-C) functionality also depends on the receiver (see below).

Some DVD recorders with hard drives need some time to start after the VPS signal has started to be transmitted , so that the recording starts late. In these cases, it can make more sense to do without the VPS control and instead allow generous amounts of time (especially since the recording can then be edited).

When recording with VPS, the VPS time specified in the program guide or teletext must always be programmed as the start time. At any other time, even if it differs by only one minute, the recording will not start. The end time , on the other hand, is not critical; any time can be programmed, just not the same as the start time.

In addition, with VPS each program must be programmed individually. Even if two or more programs of the same station in direct succession are to be recorded, these must be programmed individually when using VPS, otherwise only the first is recorded.

VPS via DVB

With the introduction of digital television ( DVB ), the transmission of the VPS signal was initially no longer possible.

In 1997 the DVB SI (Service Information) Standard (ETSI EN 300 468) was expanded to include VPS (PDC). The SI consists of several data tables and contains, among other things, the data for the Electronic Program Guide (EPG). In addition to the previous information, the PDC descriptor (descriptor tag 0x69) can be used. This descriptor essentially consists of a label, which is composed of day, month, hour and minute. If a program is now postponed, this is noted in the EPG with the note: “The following program will be broadcast with a new start time”, but the receiver recognizes from the label that it is the same program and starts recording later. The recording lasts as long as the EPG is currently running.

In addition, in 2000, the ETSI EN 301 775 standard created the basis for transmitting the familiar analog (see above) VPS signals via DVB. As with teletext, this is done on the basis of VBI (Vertical Blanking Information). It enables the VPS signal to be inserted at the analog receiver output (e.g. SCART ), so that a video recorder can record again using VPS. However, this standard is only supported by very few DVB receivers. There is a plug-in for Linux-based satellite receivers that can be used with VPS.

Another method, which was specially developed for digital transmission paths (e.g. DVB ) and for digital end devices (e.g. PVR , PDR ), was first published by ETSI in 2004 . It is known under the name Accurate Recording (also “Perfect Recording” or “Automatic Time Control” or “Signal-Supported Recording”) and in Germany it is mainly supported by public broadcasters (there called the “PDC Descriptor” method). A detailed description of this procedure can be found in chapter 11 of the technical specification ETSI TS 102 323 V1.5.1 (2012-01).

Thus, various solutions were created that are designed for different end devices (HDD recorder or video recorder).

German-speaking broadcasters with a functioning VPS signal

ARD ( Das Erste ), Arte , BR , ARD-alpha , 3sat , hr , KiKA , MDR , NDR , ORF eins , ORF 2 , ORF III , ServusTV , Phoenix , Radio Bremen , RBB , SRF 1 , SRF two , SR , SWR , Tele 5 , WDR , ZDF

See also

literature

  • Hübscher, Geißler, Groth, Petersen, Schieder, Szapanski: Electronics specialist training in communication electronics 2, radio / television / radio technology . Westermann, 1989, ISBN 3-14-221330-9 .
  • To the second . In: Audio Video Foto Bild , issue 12/2011, pp. 16/17, ISSN  1613-3161

Web links

Individual evidence

  1. ↑ MDR television - via antenna, satellite and cable
  2. ↑ ETSI EN 301 775 V1.2.1 (2003-05) (PDF; 94 kB)
  3. ↑ Perfect Recording (posts in a forum), accessed on June 1, 2016
  4. ↑ EPG automatic time control (posts in a forum), accessed on June 1, 2016
  5. ↑ What does "signal-assisted recording" mean? , accessed June 1, 2016