Content reference identifier: Difference between revisions

Revision as of 12:18, 14 February 2013

Revision as of 12:37, 14 February 2013

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== Format ==

A CRID is specified much like URLs. In fact, a CRID is a so-called [[Uniform Resource Identifier|URI]]. Typically, the content ownercreator, the broadcaster or a third party will use their [[Domain Name System|DNS]]-names in a combination with a product-specific name to create globally unique CRIDs. AsThat an exampleis, let'sthe assumesyntax that [[BBC]] wanted to makeof a CRID for the Olympics in China. It may have looked something like thisis:

crid://authority/data

The ''authority'' field represents the entity that created the CRID and its format is that of a DNS name. The ''data'' field represents a string of characters that will unambiguously identify the content within the authority scope (it is a string of characters assigned by the authority itself).

As an example, let's assume that [[BBC]] wanted to make a CRID for (all the programs of) the Olympics in China. It may have looked something like this

crid://bbc.co.uk/olympics/2008/

This would be a group CRID, that is, a CRID representing a group of contents. Then, to refer to a specific event - such as the women's shot-put final - they could have used the following inside their metadata.

crid://bbc.co.uk/olympics/2008/final/shotput/women

Currently,{{When?|date=January 2013}} four types of CRIDs are playing a major role in some [[Unidirectional networks|unidirectional]] [[Television network|television networks]]: programme CRID, series CRID, group CRID, and recommendation CRID. One of the most important applications of CRIDs is the so-called series link recording function (SL) of modern digital video recorders ([[Digital_video_recorder|DVR]], [[Personal_video_recorder|PVR]]).

In turn, a locator is a string of characters that contains all the necessary information for a receiver to find and acquire a given content, whether it is received through a transport stream, located in local storage, downloaded as a file from an Internet server, or through a streaming service. For example, a DVB locator will include all the necessary parameters to identify a specific content within a transport stream: network, transport stream, service, table and/or event identifiers.

The locators’ format, as established in TV-Anytime, is quite generic and simple, and corresponds to:

<transport-mechanism>:<specific-data>

The first part of the locator’s format (the transport mechanism) must be a string of characters that is unique for each mechanism (transport stream, local file, HTTP Internet access…). The second part must be unambiguous only within the scope of a given transport mechanism and will be standardized by the organism in charge of the regulation of the mechanism itself.

For instance, a DVB locator to identify a content within the transport stream of networks that follow this standard would be:

dvb://112.4a2.5ec;2d22~20121212T220000Z—PT01H30M

which would indicate a content (identified by the string “2d22”) that airs on a channel available on a DVB network identified by the address “112.4a2.5ec” (network “112”, transport stream “4a2” and service “5ec”), on 12/12/2012 at 10 p.m. and with a duration of 90 minutes.

== In web casting ==