Error Detection and Handling
- Error Detection and Handling
In television technology, Error Detection and Handling (EDH) protocol is an optional but commonly used addition to the Standard Definition-Serial Digital Interface (SDI) standard. This protocol allows an SD-SDI receiver to verify that each field of video is received correctly.
The SD-SDI transmitter calculates two CRC values for each video field--one corresponding to the active picture, and corresponding to the entire field (excluding the switching lines)--and places them in an EDH ancillary data packet. The EDH packet is inserted at a specific location in each field of video. The SD-SDI receiver also generates the same two CRC values for each field and compares them against the CRC values in the received EDH packet to determine if each field of video is received without errors. The EDH packet also contains bits to signal that a prior link in a broadcast or transmission chain contained an error; equipment which receives a video signal with an incorrect CRC, and retransmits the signal, is expected to re-insert the correct CRC (which may be different if the equipment alters the video signal in any way) and set the flag indicating a prior error. This feature makes it easier to determine which link, in a multi-link chain, was the source of the error.
The EDH protocol does not provide for error correction, only error detection. Also, there is no mechanism in SD-SDI to allow a field containing errors to be retransmitted. EDH is used primarily to assist in identifying faulty equipment in a video chain so that it can be quickly replaced or repaired.
EDH is not used with high definition video, as the HD serial digital interface includes a mandatory embedded CRC for each line.
The SD-SDI EDH protocol is defined by SMPTE RP 165-1994 and the equivalent ITU standard ITU-R BT.1304
See also
* error detection and correction
External links
* [http://www.leitch.com/resources/tutorials/october.pdf Error detection and handling in digital television]
* [http://www.broadcastpapers.com/testmeasurement/TektonixDTSystems&Meas.pdf An Error Measurement Method for Television]
*Society of Motion Picture and Television Engineers: "Recommend Practice 165-1994: Error Detection and Handling". Available for purchase at the [http://www.smpte.org SMPTE website]
Wikimedia Foundation.
2010.
Look at other dictionaries:
Error — The word error has different meanings and usages relative to how it is conceptually applied. The concrete meaning of the Latin word error means wandering or straying . To the contrary of an illusion, an error or a mistake can sometimes be… … Wikipedia
error — The difference between the expected and the actual. In computing, the way that the operating system reports unexpected, unusual, impossible, or illegal events is by displaying an error number or error message. Errors range from trivial,… … Dictionary of networking
Mathematics and Physical Sciences — ▪ 2003 Introduction Mathematics Mathematics in 2002 was marked by two discoveries in number theory. The first may have practical implications; the second satisfied a 150 year old curiosity. Computer scientist Manindra Agrawal of the… … Universalium
Collision detection — For collision detection on networks see CSMA/CD Collision detection typically refers to the computational problem of detecting the intersection of two or more objects. While the topic is most often associated with its use in video games and other … Wikipedia
Business and Industry Review — ▪ 1999 Introduction Overview Annual Average Rates of Growth of Manufacturing Output, 1980 97, Table Pattern of Output, 1994 97, Table Index Numbers of Production, Employment, and Productivity in Manufacturing Industries, Table (For Annual… … Universalium
CIA transnational health and economic activities — This article deals with activities of the U.S. Central Intelligence Agency related to human survival issues, emphasizing disease and basic needs such as water and agriculture. TOC CIA activities in this area include the preparation of National… … Wikipedia
Forensic entomology and the law — Forensic entomology deals with the collection of arthropodic evidence and its application, and through a series of tests and previously set of rules, general admissibility of said evidence is determined. Ultimately, the admissibility of forensic… … Wikipedia
Viet Cong and PAVN strategy, organization and structure — US caricature of Ho Chi Minh During the Second Indochina War, better known as the Vietnam War, a distinctive land warfare strategy and organization was used by the Main Force of the People s Liberation Armed Forces (better known as the Viet Cong… … Wikipedia
On-Board Data Handling — The On Board Data Handling (OBDH) subsystem of a spacecraft is the subsystem which carries and stores data between the various electronics units and the ground segment, via the Telemetry, Tracking and Command (TTC) subsystem. In the earlier… … Wikipedia
Digital video testing — in broadcast video, for example, is the process of validating and verifying that the video content and other data is being correctly processed, stored and transported. Despite the fact that the data is digital, most digital tv (DTV) system… … Wikipedia
