Uniform Resource Identifiers for Digital Video Broadcasting (DVB)
draft-mcroberts-uri-dvb-02

Abstract

This document defines the "dvb" URI scheme for the benefit of the Internet community, given its definition as part of the Digital Video Broadcasting (DVB) suite of ETSI standards.

Status of this Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at http://datatracker.ietf.org/drafts/current/.

Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as “work in progress.”

This Internet-Draft will expire on January 5, 2011.

Copyright Notice

Copyright (c) 2010 IETF Trust and the persons identified as the document authors. All rights reserved.

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.

1.  Introduction

Standards governing televisions, set-top boxes and other consumer electronics devices have for some time been developed with the Internet in mind. The use of Universal Resource Identifiers (URIs) [RFC 3986] (Berners-Lee, T., Fielding, R., and L. Masinter, “Uniform Resource Identifier (URI): Generic Syntax,” January 2005.) is now commonplace, including for the purpose of identifying resources delivered by way of terrestrial, satellite and cable broadcasts.

For this purpose, a URI scheme was developed as part of the Digital Video Broadcasting (DVB) suite of standards specifically for the purpose of identifying broadcasts delivered by way of DVB-compliant broadcasting systems.

2.  dvb URI Registration

URI scheme name.

dvb

Status.

provisional

URI scheme syntax.

See Table 1 of [ETSI TS 102 851] (European Broadcasting Union, DVB Project, and European Telecommunications Standards Institute, “Digital Video Broadcasting (DVB); Uniform Resource Identifiers (URI) for DVB Systems,” January 2010.)

URI scheme semantics.

The dvb scheme references services and resources which are transmitted using Digital Video Broadcasting-compliant broadcasting systems.

Encoding considerations.

See Section 5 of [ETSI TS 102 851] (European Broadcasting Union, DVB Project, and European Telecommunications Standards Institute, “Digital Video Broadcasting (DVB); Uniform Resource Identifiers (URI) for DVB Systems,” January 2010.)

Applications/protocols that use this URI scheme name.

dvb URIs are used throughout DVB-compliant broadcasting systems, for example within Freeview and Freesat in the United Kingdom. They are also used in TV-Anytime [tva] (, “TV Anytime Forum,” .) metadata where it relates to services transmitted by DVB systems.

Interoperability considerations.

None known.

Security considerations.

See Section 5 (Security Considerations).

Contact.

Mo McRoberts <mo.mcroberts@nexgenta.com>

Author/Change controller.

Mo McRoberts <mo.mcroberts@nexgenta.com>

References.

See Section 6.

3.  Digital Video Broadcasting URI

The DVB URI is defined by [ETSI TS 102 851] (European Broadcasting Union, DVB Project, and European Telecommunications Standards Institute, “Digital Video Broadcasting (DVB); Uniform Resource Identifiers (URI) for DVB Systems,” January 2010.), and that shall be considered the authoritative source of the definition of the scheme-specific-part of the DVB URI. The remainder of this section is therefore non-normative.

URIs employing the dvb scheme are URLs. DVB URLs may refer to any of the following kinds of resource:

• A DVB service
• Components within a DVB service (such as an audio or video stream)
• An event (for example, a programme)
• A transport stream
• A file contained within a DSM-CC object carousel
• Interactive applications

3.1.  Syntax

DVB URLs conform to one of the two following formats:

"dvb://" <original_network_id> "." [ <transport_stream_id> ] [ "." <service_id> [ "." <component-set> [ "$" <carousel-id> ] ] [ <event-constraint> ] ] [ <path-absolute> ]

"dvb://'" <textual_service_id> "'" [ "." <component-set> [ "$" <carousel-id> ] ] [ <event-constraint> ] [ <path-absolute> ]

The URL format is defined in terms of the Augmented Backus-Naur Form (ABNF) notation of [RFC 5234] (Crocker, D., Ed. and P. Overell, “Augmented BNF for Syntax Specifications: ABNF,” January 2008.) below. The ABNF below makes use of the following core ABNF syntax rules defined by that specification: DIGIT, ALPHA, and HEXDIG. Additionally, it below makes use of host, path-absolute, unreserved and pct-encoded as defined by [RFC 3986] (Berners-Lee, T., Fielding, R., and L. Masinter, “Uniform Resource Identifier (URI): Generic Syntax,” January 2005.).

dvb_url             =  scheme ":" hier-part

scheme              =  "dvb"

hier-part           =  net-path / abs-path

net-path            =  "//" ( entity [ abs-path ] ) / app-entity

entity-path         =  entity abs-path

entity              =  ts | service | service-comp

ts                  =  original_network_id "." transport_stream_id

service             =  service-no-event [ event-constraint ]

service-comp        =  service-no-event "." component-set
                       [ "$" carousel-id ]
                       [ event-constraint ]

service-no-event    =  orignal_network_id "." [ transport_stream_id ]
                       "." service_id | "'" textual_service_id "'"

component-set       =  comp-tag-set | qual-comp-set

comp-tag-set        =  component_tag *( "&" component_tag )

qual-comp-set       =  qual-comp *( "&" qual-comp )

qual-comp           =  comp-type "=" component-id

comp-type           =  "video" | "audio" | "data" | "subtitle"
                       | "teletext" | "dvbst"

component-id        =  component_string | "default" | "current"
                       | "hearing_impaired" | "visually_impared"
                       | "none"

component_string    =  iso639-lang-code | component_tag

app-entity          =  svc-context | svc-comp-context
                       | ait-specifier

svc-context         =  "current" | "original"

svc-comp-context    =  "current.audio" | "current.video"
                       | "current.av"

ait-specifier       =  ait-filter "." "ait" ait-abs-path

ait-filter          =  "current" | service-no-event

ait-abs-path        =  "/" ait-entity

ait-entity          =  "app_root" | ait-app

ait-app             =  org_id_part "." app_id_part [ "?" ait-params ]

ait-params          =  "arg_" 1 * digit "=" *uric [ "&" ait-params ]

event-constraint    =  event-id-mode | tva-id-only-mode | timespec

event-id-mode       =  ";" event_id [ ";" tva-id ] [ timespec ]

tva-id-only-mode    =  ";;" tva-id [ timespec ]

timespec            =  "~" start-time "--" duration

start-time          =  date "T" time "Z"

duration            =  "PT" hours "H" minutes "M" [ seconds "S" ]

date                =  year month day

time                =  hours minutes [ seconds ]

carousel-id         =  transaction_id ; [ETSI EN 301 192]

original_network_id =  hex_string

transport_stream_id =  hex_string

service_id          =  hex_string

component_tag       =  hex_string

event_id            =  hex_string

transaction_id      =  hex_string

abs-path            =  path-absolute  ; [RFC 3986], Section 3.3

textual_service_id  =  host           ; [RFC 3986], Section 3.2.2

org_id_part         =  1 * HEXDIG     ; [ETSI TS 102 812]

app_id_part         =  1 * HEXDIG     ; [ETSI TS 102 812]

iso639-lang-code    =  3 * ALPHA

hex_string          =  1 * HEXDIG

tva-id              =  1 * HEXDIG

year                =  4 DIGIT

month               =  2 DIGIT

day                 =  2 DIGIT

hours               =  2 DIGIT

minutes             =  2 DIGIT

seconds             =  2 DIGIT

uric                =  unreserved / pct-encoded / ";" / "?" / ":"
                       / "@" / "&" / "=" / "+" / "$" / "," / "/"

3.2.  Historical Syntax

Prior to the standardisation of [ETSI TS 102 851] (European Broadcasting Union, DVB Project, and European Telecommunications Standards Institute, “Digital Video Broadcasting (DVB); Uniform Resource Identifiers (URI) for DVB Systems,” January 2010.), a syntax for dvb URIs was defined by [DAVIC9] (Digital Audio-Video Council, “DAVIC 1.4.1 Specification Part 9: Information Representation,” 1999.), Section 9.5.2. The syntax defined in [ETSI TS 102 851] (European Broadcasting Union, DVB Project, and European Telecommunications Standards Institute, “Digital Video Broadcasting (DVB); Uniform Resource Identifiers (URI) for DVB Systems,” January 2010.) was designed to allow applications to work with both the current DVB syntax of URIs and also the historical syntax defined by DAVIC.

The syntax below makes use of HEXDIG from the core ABNF syntax rules defined by [RFC 5234] (Crocker, D., Ed. and P. Overell, “Augmented BNF for Syntax Specifications: ABNF,” January 2008.). Additionally, it makes use of unreserved and escaped as defined by [RFC 3986] (Berners-Lee, T., Fielding, R., and L. Masinter, “Uniform Resource Identifier (URI): Generic Syntax,” January 2005.).

dvb_url             =  scheme ":" hier-part

scheme              =  "dvb"

hier-part           =  net-path / abs-path

net-path            =  "//" entity [ abs-path ]

entity              =  transport-stream / service / service-component

transport-stream    =  original_network_id "." transport_stream_id

service             =  original_network_id [ "."
                       transport_stream_id ] "." service_id
                       [ event-constraint ]

service-component   =  service "." component-tag-set
                       [ event-constraint ]

component-tag-set   =  component-tag *( "&" component-tag )

event-constraint    =  ";" event_id

abs-path            =  "/" segment

path_segments       =  segment *( "/" segment )

segment             =  *pchar *( ";" param )

param               =  *pchar

pchar               =  unreserved | escaped | ":" | "@" | "&" | "="
                       | "+" | "$" | ","

original_network_id =  hex_string

transport_stream_id =  hex_string

service_id          =  hex_string

component_tag       =  hex_string

event_id            =  hex_string

hex_string          =  1 * HEXDIG

3.3.  Examples

dvb://1041.10bf

DVB transport stream

dvb://233a.1041.10bf

DVB service

dvb://233a.1004.1044;8fff

Event within a DVB service

dvb://233a.1004.1044;8fff~20100706T000315Z--PT00H03M00S

Time-constrained event on a DVB service

dvb://233a.1004.1044;8fff@2010-07-06T00:03:15Z/PT00H03M00S

Time-constrained event on a DVB service (historical syntax)

dvb://233a.1041.10bf/doc/form.pdf

File in a subdirectory of the default object carousel of a specific DVB service

dvb:/image.png

File in root directory of the default object carousel on the current service

4.  IANA Considerations

Registration will be submitted to IANA for the scheme described in Section 2 (dvb URI Registration).

5.  Security Considerations

Section 7 of [RFC 3986] (Berners-Lee, T., Fielding, R., and L. Masinter, “Uniform Resource Identifier (URI): Generic Syntax,” January 2005.) describes general security considerations for URI schemes. The sections relating to reliability and consistency, malicious construction, back-end transcoding, rare IP address formats and semantic attacks all apply to dvb URIs. The section relating to sensitive information does not apply, given that dvb URIs do not contain authentication information.

The security considerations of the Digital Video Broadcasting suite of standards in general are not covered in this document.

6.  References

6.1. Normative References

6.2. Informative References

Author's Address