This document defines the application/xml+ttml media type and provides a registry of identified TTML processor profiles. A processor profile is an identified reference to a set of capabilities that a processor supports, which may be defined in a specification document, a TTML Profile Definition Document or both.

This is a registry and may be updated without any notices.

Purpose

TTML defines a MIME type/subtype, application/ttml+xml, that may be used to identify the content type of TTML resources. In addition, TTML as well as other W3C and non-W3C specifications define a number of processor profiles which define requirements on compliant processors that may decode and process a TTML document. This registry can be used by other entities to exchange processor profiles in a compact way. In certain TTML use cases, it is desirable for a processor to proceed with TTML resource fetch, decode, and processing only if it can be determined that the referenced resource is tentatively processable. In order to satisfy such use cases, it is possible for the referencing context to enumerate one or more named profiles, which, if supported by the processor, would allow a first-order determination to be made about whether a resource may be processed. We say first order here since during actual decoding of a TTML resource, the processor profile declarations contained within the resource may result in the resource being rejected.

This registry is intended to provide a central location for enumerating identified TTML profiles, or, more strictly speaking, TTML decoder/processors, where each entry in the registry identifies a particular profile which is understood to implement a processor capable of satisfying the constraints of a defined TTML processor profile that takes the form of a TTML Profile Definition Document. By utilizing a common registry, it is possible to avoid name collisions among different profile defining fora.

Note Well that, in the context of this registry, when we use the term profile, we mean processor profile. We explicitly do not mean content profile. That is, nothing about the use of the profile parameter described here is intended to be used to identify or make claims about whether a TTML resource conforms with a TTML Content Profile or any type of TTML Profile that may be interpreted in whole or in part as making statements about the conformance of a TTML resource or the features of TTML (or other external specifications) actually used in the resource.

Applications using the entries in this registry are encouraged to adopt the following combination syntax:

Employ two combination operators, '+' (AND) and '|' (OR), which may be used to specify, respectively, that multiple processor profiles apply (simultaneously) or that any processor profile of a list of profiles may apply individually. If both operators are used in a codecs value, then the '+' operator has precedence.

The example: "A+B|C+D|E" states that a TTML processor that implements any one of A+B or C+D or E processor profiles satisfies the requirements to fetch and begin decode/processing of a TTML document, where X+Y means that both X and Y processor profiles must be supported, and X|Y means that either X or Y processor profile must be supported

For more information about processor profile combination, see TTML2 Profile Combination (https://www.w3.org/TR/ttml2/#profile-attribute-processorProfileCombination) [[!TTML2]].

Media Type Registration

This section updates the media type, "application/ttml+xml" to add a new parameter, codecs. All other provisions of the media type specification remain the same. This supersedes the initial registration information in TTML 1.0 Second Edition.

This section is in conformance with BCP 13 and W3CRegMedia. The information in this appendix is being submitted to the Internet Engineering Steering Group (IESG) for review, approval, and registration with the Internet Assigned Numbers Authority (IANA).

Type name:

application

Subtype name:

ttml+xml

Required parameters:

None.

Optional parameters:
charset

If specified, the charset parameter must match the XML encoding declaration, or if absent, the actual encoding. See also Encoding Considerations below.

profile

The document profile of a TTMLDocument Instance may be specified using an optional profile parameter, which, if specified, the value of which must adhere to the syntax and semantics of ttp:profile parameter defined by TTML 1.0 Second Edition, Section 6.2.8 ttp:profile of the published specification.

codecs

The optional codecs parameter provides a short form version of the profile parameter with multiple-profile combinatorial capability. If a short (4-character) form of a profile is registered in the TTML Profile Registry, it is recommended that this codecs parameter be used and not the profile parameter. The nominal value of this parameter is a single 4 character code from the registry.

Additionally, applications using the entries in the registry are encouraged to adopt the following combination syntax:

Employ two combination operators, '+' (AND) and '|' (OR), which may be used to specify, respectively, that multiple processor profiles apply (simultaneously) or that any processor profile of a list of profiles may apply individually. If both operators are used in a codecs value, then the '+' operator has precedence.

The example: "A+B|C+D|E" states that a TTML processor that implements any one of A+B or C+D or E processor profiles satisfies, at first order, the requirements to fetch and begin decode/processing of a TTML document, where X+Y means that both X and Y processor profiles must be supported, and X|Y means that either X or Y processor profile must be supported.

For more information about processor profile combination, see TTML2 Profile Combination.

Encoding considerations:

Same for application/xml, except constrained to either UTF-8 or UTF-16. See IETF RFC 7303, XML Media Types, Section 3.2. For the purpose of filling out the IANA Application for Media Type (http://www.iana.org/cgi-bin/mediatypes.pl), the value binary applies.

Security considerations:

As with other XML types and as noted in IETF RFC 7303, XML Media Types, Section 10, repeated expansion of maliciously constructed XML entities can be used to consume large amounts of memory, which may cause XML processors in constrained environments to fail.

In addition, because of the extensibility features for TTML and of XML in general, it is possible that "application/ttml+xml" may describe content that has security implications beyond those described here. However, TTML does not provide for any sort of active or executable content, and if the processor follows only the normative semantics of the published specification, this content will be outside TTML namespaces and may be ignored. Only in the case where the processor recognizes and processes the additional content, or where further processing of that content is dispatched to other processors, would security issues potentially arise. And in that case, they would fall outside the domain of this registration document.

Although not prohibited, there are no expectations that XML signatures or encryption would normally be employed.

Interoperability considerations:

The published specification describes processing semantics that dictate behavior that must be followed when dealing with, among other things, unrecognized elements and attributes, both in TTML namespaces and in other namespaces.

Because TTML is extensible, conformant "application/ttml+xml" processors may expect (and enforce) that content received is well-formed XML, but it cannot be guaranteed that the content is valid to a particular DTD or Schema or that the processor will recognize all of the elements and attributes in the document.

Published specification:

This media type registration is extracted from the TTML Profile Registry.

Applications that use this media type:

TTML is used in the television industry for the purpose of authoring, transcoding and exchanging timed text information and for delivering captions, subtitles, and other metadata for television material repurposed for the Web or, more generally, the Internet.

There is partial and full support of TTML in components used by several Web browsers plugins, and in a number of caption authoring tools.

Additional information:
Magic number(s):
File extension(s):

.ttml

Macintosh file type code(s):

"TTML"

Fragment identifiers:

For documents labeled as application/ttml+xml, the fragment identifier notation is intended to be used with xml:id attributes, as described in section 7.2.1 of the Timed Text Markup Language 1 (TTML1) specification.

Person & email address to contact for further information:

Timed Text Working Group (public-tt@w3.org)

Intended usage:

COMMON

Restrictions on usage:

None

Author:

The published specification is a work product of the World Wide Web Consortium's Timed Text (TT) Working Group.

Change controller:

The W3C has change control over this specification.

Registration Entry Requirements and Update Process

  1. Each entry must include a unique identification, where the scope of uniqueness is the set of identifiers defined in this registry. An identifier must conform with the element non-terminal of RFC6381 and, furthermore, may not contain any of the characters in the regular expression character class [+|].
  2. Each entry must include an absolute URI that serves as the TTML Profile Designator that identifies the processor profile.
  3. Each entry should include a link that references a TTML Profile Definition Document that formally specifies the processor profile using TTML profile definition vocabulary.
  4. Each entry should include a link that references a public available specification (PAS) that defines the identified processor profile.
  5. Each entry must include contact information of the requestor.

An update to this registry is an addition, change or deletion of an entry. Any person can request an update to this registry by email notice to the chairman of the Timed Text Working Group who will place it on an upcoming meeting agenda and notify the requestor. Consideration and disposition of the request is by consensus of the W3C Timed Text Working Group. The Chair will then notify the requestor of the outcome and update the registry accordingly. Although profiles can be deleted, there is no intent to re-use deleted profile values. That is, the intent is that profile entries are "stable".

Registry

This section is the registry of short form profile identifiers. The first sub-section details how such identifiers should be dereferenced to profile designators, the specifications that define those profiles, and the contact organisation for each profile. The second sub-section describes the mechanism used by each profile to permit identification of the profile of a TTML Document Instance by inspection of that document.

Profile designator and specifications

The following table defines the Profile Designator for each short form Profile Identifier in this Registry, alongside the public specification document in which the profile is defined, and the relevant contact organisation.

Profile Identifier Profile Designator Public Specification(s) Requestor Contact
tt1f http://www.w3.org/ns/ttml/profile/dfxp-full [[!TTML1]] TTWG
tt1p http://www.w3.org/ns/ttml/profile/dfxp-presentation [[!TTML1]] TTWG
tt1s http://www.w3.org/ns/ttml/profile/sdp-us [[!TTML10-SDP-US]] TTWG
tt1t http://www.w3.org/ns/ttml/profile/dfxp-transformation [[!TTML1]] TTWG
im1t http://www.w3.org/ns/ttml/profile/imsc1/text [[!TTML-IMSC1]] TTWG
im1i http://www.w3.org/ns/ttml/profile/imsc1/image [[!TTML-IMSC1]] TTWG
etx1 urn:ebu:tt:exchange:2012-07 [[!EBU-TT-1]] EBU
etx2 urn:ebu:tt:exchange:2015-09 [[!EBU-TT-1]] EBU
etd1 urn:ebu:tt:distribution:2014-01 [[!EBU-TT-D]] EBU
cft1 http://www.decellc.org/profile/cff-tt-text-1.1 [[!UV-DMedia]] DECE
cfi1 http://www.decellc.org/profile/cff-tt-image-1.1 [[!UV-DMedia]] DECE
ede1 urn:IRT:ebu-tt-basic-de:2013-07 IRT Technical Guidelines IRT

Path  and value

The following table describes how to identify the profile of a given TTML Document Instance for each profile in this Registry, by inspecting the document, where possible. The XPATH defines where a profile-identifying value can be found within the document instance, and the Value column specifies the value that the resultant data has if the document instance claims conformance to the profile. Where a TTML Profile Definition Document is available this is also listed.

Profile Identifier XPATH to element or attribute* Value of element or attribute* Profile Definition Document
tt1f /tt/head/ttp:profile/@use or
/tt/@ttp:profile
http://www.w3.org/ns/ttml/profile/dfxp-full DFXP Full Profile
tt1p /tt/head/ttp:profile/@use or
/tt/@ttp:profile
http://www.w3.org/ns/ttml/profile/dfxp-presentation DFXP Presentation Profile
tt1s /tt/head/ttp:profile/@use http://www.w3.org/ns/ttml/profile/sdp-us SDP US Profile
tt1t /tt/head/ttp:profile/@use or
/tt/@ttp:profile
http://www.w3.org/ns/ttml/profile/dfxp-transformation DFXP Transformation Profile
im1t /tt/@ttp:profile or
/tt/head/metadata/ebuttm:documentMetadata/ebuttm:conformsToStandard
http://www.w3.org/ns/ttml/profile/imsc1/text n/a
im1i /tt/@ttp:profile http://www.w3.org/ns/ttml/profile/imsc1/image n/a
etx1 /tt/head/metadata/ebuttm:documentMetadata/ebuttm:documentEbuttVersion v1.0 n/a
etx2 /tt/head/metadata/ebuttm:documentMetadata/ebuttm:documentEbuttVersion urn:ebu:tt:exchange:2015-09 n/a
etd1 /tt/head/metadata/ebuttm:documentMetadata/ebuttm:documentEbuttVersion urn:ebu:tt:distribution:2014-01 n/a
cft1 ... ... n/a
cfi1 ... ... n/a
ede1 /tt/preceding-sibling::comment()[1] Profile: EBU-TT-D-Basic-DE n/a

The following considerations apply when resolving the XPATH expressions: