Video Disk Control Protocol: Difference between revisions

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{{Short description|Communication protocol}}

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'''Video Disk Control Protocol''' ('''VDCP''') is a [[proprietary communications protocol]] primarily used in [[broadcast automation]] to control [[hard disk]] [[video server]]s for [[broadcast television]]. [[VDCP]] was originally developed by [[Louth Automation]] and is commonly called the '''Louth Protocol'''. At the time it was developed, Hewlett Packard (whose broadcast server division was eventually sold to [[Pinnacle Systems]]) and [[Tektronix]] were both bringing to market the first of the VideoFile Servers to be used in the broadcast industry. They contacted Louth Automation who then designed the [[communications protocol]] basing it on Sony protocols of both the Sony LMS Storage Device and the Sony VTR. The principal work was carried out by Ken Louth at Louth Automation.

The video disk communications protocolVDCP uses a tightly coupled master-slave methodology. The controlling device takes the initiative in communications between the controlling devicebroadcast ([[automation)]] device and the controlled device (video disk). The topology is point to point. The videodisk protocolVDCP conforms to the OSI[[Open (openSystems systemInterconnection]] interconnection(OSI) reference model.

'''Video Disk Control Protocol''' ('''VDCP''') is a [[communications protocol]] primarily used to control [[hard disk]] systems dedicated to the recording and playback of video and audio content in the broadcast industry. VDCP was originally developed by [[Louth Automation]] and used to be called Louth Protocol.

VDCP is a [[serial communications]] protocol based on [[RS-422]]. It is derived from the [[Sony]] [[9-Pin Protocol]], an industry-standard protocol for control of professional broadcast [[VTR]]s that is used in [[Online editing (video production)|online editing]].

The video disk communications protocol uses a tightly coupled master-slave methodology. The controlling device takes the initiative in communications between the controlling device (automation) and the controlled device (video disk). The topology is point to point. The videodisk protocol conforms to the OSI (open system interconnection) reference model.

Full details of the protocol are available from Imagine Communications who, as Harris Broadcast, acquired Louth in 2000.

It was largely succeeded by the [[Network Device Control Protocol]].<ref name="q429">{{cite web | title=Harris launches network-based automation protocol for controlling broadcast audio/video devices | website=Digital Broadcasting com | date=2001-02-14 | url=https://www.digitalbroadcasting.com/doc/harris-launches-network-based-automation-prot-0001 | access-date=2025-08-14}}</ref>

Layer 1 is the physical layer which consists of the electrical and mechanical specifications.

==References==

Layer 2, the data link level, covers the synchronization and error control for the information transmitted over the physical link.

{{Reflist}}

==External links==

Layers 3 and 4 provide network functionality and are not applicable.

* [http://imaginecommunications.com/ Imagine Communications (formerly Harris Broadcast)]

* [http://www.harris.com//view_pressrelease.asp?act=lookup&pr_id=476 NDCP Launch press release]

[[Category:Broadcast engineering]]

Layer 5, the session layer, provides the control structure for communications between applications: establishes, manages, and terminates connections (sessions) between cooperating applications.

[[Category:Television technology]]

[[Category:Digital television]]

[[Category:Television terminology]]

Layer 6, the presentation layer, contains the control language (dialect).

{{tv-tech-stub}}

The commands tables and command description provides this functionality. A time line command set has been included for systems that must use the protocol over a nondeterministic network environment.

==Electrical and Mechanical Specifications==

1. Communications Signal

a. Asynchronous bit serial, word serial

b. Conforms to EIA RS-422A

c. Full duplex communications channel

d. Transfer rate: 38.4 kb/s.

2. Bit Configuration

a. 1 start bit (space)

b. 8 data bits

c. 1 parity bit (odd)

d. 1 stop bit (mark)

e. Byte time = .286 msec.

3. Connection (9 Pin D-subminiature)

PIN - CONTROLLING DEVICE - CONTROLLED DEVICE

1 - Frame Ground - Frame Ground

2 - Receive A - Transmit A

3 - Transmit B - Receive B

4 - Transmit Common - Receive Common

5 - Spare - Spare

6 - Receive Common - Transmit Common

7 - Receive B - Transmit B

8 - Transmit A - Receive A

9 - Frame Ground - Frame Ground

==External links==

Information source and detailed protocol documents

* [http://www.broadcast.harris.com/support/protocols.asp Protocols]

* [http://www.broadcast.harris.com/support/kb/supportdocs.asp?fid=1250 Support documents]

* [http://support.omneon.com/Updates/Omneon/Documentation/vdcp.pdf Documentation] ([[Portable Document Format|PDF]])