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== Overview ==▼
A '''content reference identifier''' or '''CRID''' is a concept from the standardization work done by the [[TV-Anytime]] forum. It is or closely matches the concept of the [[Uniform Resource Locator]], or URL, as used on the [[World-Wide Web]]:
{{Quotation|A unit of content, in a [[Broadcasting|broadcast stream]], can be referred to by its globally unique CRID in the same way that a [[webpage]] can be referred to by its globally unique URL on the web.}}<!--source? or is it not a quotation?-->
The concept of CRID permits
The receiver must be capable of resolving these unambiguous references, i.e.
This framework allows for the separation between the reference to a given content (the CRID) and the necessary information to acquire it, which is called a “locator”. Each CRID may lead to one or more locators which will represent different copies of the same content. They may be identical copies broadcast in different channels or dates, or cost different prices. They may also be distinct copies with different technical parameters such as format or quality.
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It may also be the case that the resolution process of a CRID provides another CRID as a result (for example, its reference in a different network, where it has an alternative identifier assigned by a different operator) or a set of CRIDs (for instance, if the original CRID represents a TV series, in which case the resolution process would result in the list of CRIDs representing each episode).
From the above it
A CRID is not exactly a universal, unique and exclusive identifier for a given content. It is closely related to the authority that creates it, to the resolution service provider, and to the content provider in such a way that the same content may have different CRIDs depending on the field in which they are used (for example, a different one for each television operator that has the rights to broadcast the content).
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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 creator, 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. That is, the syntax of a CRID is:
crid://authority/data
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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
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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
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 December 2012 at 10 p.m. and with a duration of 90 minutes.▼
dvb://112.4a2.5ec;2d22~20121212T220000Z—PT01H30M
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== The ___location resolution process ==
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In May 2005, an Informational RFC, [http://tools.ietf.org/html/rfc4078 No 4078], was published as the start of this work.
The long-term goal is that CRIDs should be available for use by [[cell phones]], [[Personal digital assistant|PDA]]s, [[Digital television|digital TV]] [[Set-top box|receivers]] and other [[Consumer electronics|consumer devices]] for fetching content, either from a broadcast stream or over [[
* [[BBC Programme Identifier]]
== References ==
* [
* [
* [http://www.etsi.org/deliver/etsi_ts/102800_102899/10282202/01.04.01_60/ts_10282202v010401p.pdf ETSI TS 102 822-2 V1.4.1 (2007–11), Page 19, Section 5: "TV-Anytime content referencing scenarios"] Accessed 3 December 2012
* [http://www.etsi.org/deliver/etsi_ts/102800_102899/10282204/01.07.01_60/ts_10282204v010701p.pdf ETSI TS 102 822-4 V1.7.1 (2012–12), Page 13, Section 8: "CRID"] Accessed 9 January 2013
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