Sustainability of Digital Formats: Planning for Library of Congress Collections
Sustainability of Digital Formats: Planning for Library of Congress Collections |
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| Introduction | Sustainability Factors | Content Categories | Format Descriptions | Contact | |
| Full name | Synchronized Multimedia Integration Language (SMIL) |
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| Description |
Synchronized Multimedia Integration Language (SMIL), pronounced “smile”, is a World Wide Web Consortium (W3C) open standard, extensible markup language prepared by the Synchronized Multimedia Working Group (SYMM WG). The Synchronized Multimedia Integration Language (SMIL 3.0), W3C Recommendation 01 December 2008 (referenced throughout this document) standard is the most current version, extending functionalities contained in SMIL 2.1, but also introduces some new modules and defines 3 new profiles. SMIL 3.0 standard describes multimedia presentations, defining object timing, layout, animation, transition, and linked media elements. The standard states SMIL 3.0’s main design goal as “Define an XML-based language that allows authors to write interactive multimedia presentations. Using SMIL 3.0, an author may describe the temporal behavior of a multimedia presentation, associate hyperlinks with media objects and describe the layout of the presentation on a screen.” Structure of SMIL 3.0 SMIL 3.0 standard defines a set of markup modules, their semantics and XML syntax. SMIL 3.0 uses the concepts of Modularization and Profiling for integrating functionality.
SMIL 3.0 Scalability Framework - SMIL 3.0 includes functionality for various multimedia services (text, images, video, etc) for various platforms (desktops, mobile phones, car navigation, etc.), with each platform having their own specific requirements. SMIL 3.0 groups similar elements/attributes together (Modules) to produce Profiles that meet the needs of the different platforms. As stated in the standard, “For example, a hand held device, digital talking book player, or a mobile phone may only support a small subset of SMIL 3.0 modules in its own profile.” Modules:
Profiles: SMIL 3.0 Language Profile: contains support for all the major SMIL 3.0 features SMIL 3.0 UnifiedMobile Profile: provides support for SMIL 3.0 Language and mobile devices (high-resolution display, sufficient memory/processor for rendering SMIL documents) SMIL 3.0 DAISY Profile: tailored specifically for the DAISY standard and DAISY digital talking books SMIL 3.0 Tiny Profile: simple SMIL presentations for devices with reduced capabilities, such as MP3/MP4 players or car navigation systems SMIL 3.0 smilText Profile: support for external streaming text container, referenced outside of the content of the SMIL file - W3C’s Simple SMIL Example (listing multiple media files and sequence): Uses of SMIL 3.0 As stated in the standard’s introduction, “Using SMIL 3.0, an author may describe the temporal behavior of a multimedia presentation, associate hyperlinks with media objects and describe the layout of the presentation on a screen.” The SMIL format is increasingly being used for the creation and customization of digital signage. According to Garlic-Player.com’s resource article, SMIL suits perfect for Digital Signage, December 2022, “SMIL is an investment safe industrial standard from the W3- Consortium. Everyone can use SMIL to create applications without paying license fees. Companies are no more forced to reinvent the wheel. They can use solid field proven and powerful concepts which covers every use case... Overall, SMIL is a powerful and flexible language that is well-suited for creating and managing multimedia content. A-Smil.org is a website dedicated to “Advocacy for SMIL as an open standard for digital signage.” |
| Relationship to other formats | |
| Defined via | XML,
Extensible Markup Language (XML). SMIL defines an XML-based language. |
| Defined via | XML 1.0,
Extensible Markup Language (XML) 1.0. Per standard, “The SMIL 3.0 Conformant document MUST conform to the following W3C Recommendations: The XML 1.1 specification (Extensible Markup Language (XML) 1.1). Note: SMIL 3.0 conforms to both XML 1.1 and XML 1.0, with XML 1.1 being the definitive reference because it is newer.” |
| Defined via | XML 1.1,
Extensible Markup Language (XML) 1.1. Per standard, “The SMIL 3.0 Conformant document MUST conform to the following W3C Recommendations: The XML 1.1 specification (Extensible Markup Language (XML) 1.1). Note: SMIL 3.0 conforms to both XML 1.1 and XML 1.0, with XML 1.1 being the definitive reference because it is newer.” |
| Defined via | XHTML 1.1,
Extensible HyperText Markup Language (XHTML) 1.1. Per standard, “The elements names, attributes names and attribute values of SMIL linking constructs are, where possible, the same as constructs in XHTML [XHTML11] with corresponding linking behavior.” |
| Used by | XHTML 1.0,
Extensible HyperText Markup Language (XHTML). Per standard, ‘SMIL 3.0 components are used for integrating timing into XHTML [XHTML10]” |
| Used by | SVG,
Scalable Vector Graphics (SVG) 1.1. Per standard, ‘SMIL 3.0 components are used for integrating timing into SVG [SVG].” |
| May contain | CSS,
Cascading Style Sheet (CSS) Markup. Per standard, “Any use of CSS styles and properties shall conform to Cascading Style Sheets, level 2 CSS2 Specification.” |
| Has earlier version | SMIL 2.1,
Synchronized Multimedia Integration Language (SMIL) 2.1. Not described separately at this time. See Notes for more information. Per standard, “SMIL 3.0 edition is a new version, it extends the functionalities contained in SMIL 2.1.” |
| Has earlier version | SMIL 2.0,
Synchronized Multimedia Integration Language (SMIL) 2.0. Not described separately at this time. See Notes for more information. |
| Has earlier version | SMIL 1.0,
Synchronized Multimedia Integration Language (SMIL) 1.0. Not described separately at this time. See Notes for more information. |
| May have component | TTML1,
Timed Text Markup Language Version 1 (TTML1). The TTML1 specification states “While TTML is not expressly designed for direct (embedded) integration into an HTML or a SMIL document instance, such integration is not precluded.” TTML may provide a standard content format to reference from a <text> or <textstream> media element in a SMIL 3.0 document. Vocabulary Derivation - TTML element vocabulary items are based on the syntactic and/or semantic model defined by the reference SMIL 3.0. |
| LC experience or existing holdings | Likely exists in LC collections but not separately documented. |
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| LC preference | The Library of Congress has not defined format preferences for caption or subtitle files for moving image works in the Recommended Formats Statement. |
| Disclosure | Open standard and fully documented. Synchronized Multimedia Integration Language (SMIL) 3.0 is a W3C Recommendation which is considered a Web standard. |
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| Documentation |
Synchronized Multimedia Integration Language (SMIL 3.0) | W3C Recommendation 01 December 2008. Maintained by W3C and the Synchronized Multimedia Working Group (SSMM WG). The SYMM WG closed April 1, 2012. See Format Specification below for links to previous versions. |
| Adoption |
According to Alejandro Mur in the MamutLove.com’s blog, Masks, Gradients and SMIL Animations on an SVG, October 2020, “The future of SMIL is far from being clear. It has a wide support but it could loss strength if the browsers reject it and bet for pure CSS animations and the newest Web Animations API.” According to SignageOS.io’s blog, Universal SMIL Support for Digital Signage, October 2020, “Due to improvements to the SMIL open standard and its highly cost-efficient nature, SMIL remains a viable option for digital signage content distribution. Digital signage leaders including IAdea and ViewSonic, and software providers like SignageLive first offered SMIL compatible devices and player apps as early as 2004. Since that time, few companies chose to adopt and use the SMIL open standard for publishing content because of its lack of compatibility and support in web browsers. Today, major companies like Adobe, Apple, Microsoft still maintain SMIL compatibility for various purposes.” Matt Visiwig in Is SMIL dead in 2022? Nope, September 2022, at the end of 2015 “SMIL had been sentenced to an abrupt end as Chrome announced intention to deprecate SMIL...Fast-forward to 2022 and the only browsers that don’t support SMIL are Internet Explorer (officially retired) and Opera Mini. SMIL 3.0 Interoperability Implementation Report Up-to-date browser support for SMIL on CanIUse.com. |
| Licensing and patents |
None. The W3C Patent Policy governs the handling of patents in the process of producing Web standards. The W3C Patent Policy has the goal of assuring that all W3C Recommendations can be implemented on a royalty-free basis. |
| Transparency |
SMIL 3.0 files are XML-based, so they are both human-readable and machine-readable. These files are plain text, which means they can be viewed with any text editor. While SMIL files can be written using a simple text-editor, there are authoring applications that allow users to produce SMIL presentation content. The W3C’s Synchronized Multimedia page lists a variety of Authoring Tools for SMIL. |
| Self-documentation |
The SMIL 3.0 metadata element has been expanded from SMIL 1.0 and 2.0, as described in the SMIL 3.0 Metainformation section of the standard. Overview of changes:
A SMIL 3.0 Profile ultimately determines what Metainformation is required, supported, and which elements (child elements) have metadata. According to Britta Meixner in Using SIVA XML and SMIL for Interactive Non-linear Videos: A Comparison, June 2014, “Standards like SMIL provide extensive structures to describe metadata for timing and spacing of single media elements which then forms a presentation. |
| External dependencies |
None beyond availability of supporting software/hardware. The standard defines a SMIL document player as “those applications that support playback of “application/smil+xml” documents and host language conformant document profiles.” The W3C’s Synchronized Multimedia page lists SMIL players that support the different versions of SMIL, including Ambulant 2.0, RealPlayer, and GRiNS. |
| Technical protection considerations |
RFC 4536 published May 2006 - IANA.org Regulations Security Considerations: See Section 6, "Security Considerations." Network Working Group | Request for Comments: 4536 The application/smil and
application/smil+xml Media Types, Security Considerations, Section 6:
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| Text | |
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| Normal rendering |
Good support. Per the standard, “SMIL 3.0 Conformant document MUST be well-formed XML.” See XML. |
| Integrity of document structure |
See XML. |
| Integrity of layout and display |
See XML. |
| Support for mathematics, formulae, etc. |
Little to no information on SMIL 3.0’s support of mathematics, chemical formulae, diagrams, etc. See XML. |
| Functionality beyond normal rendering |
SMIL 3.0 defines Animation Modules (optional), BasicAnimation and SplineAnimation, to incorporate animation into a presentation. See XML. |
| Tag | Value | Note |
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| Filename extension | smil |
See https://www.iana.org/assignments/media- types/application/smil. |
| Filename extension | smi |
Per IANA.org “NOTE: On the Windows operating system and the Macintosh platform, the ".smi" extension is used by other formats. To avoid conflicts, it is thus recommended to use the extension ".smil" for storing SMIL files on these platforms.” See https://www.iana.org/assignments/media- types/application/smil. |
| Filename extension | sml |
See https://www.iana.org/assignments/media- types/application/smil. |
| Internet Media Type | application/smil+xml |
Per specification. See https://www.w3.org/TR/SMIL3/smil-modules.html#smilModulesNS- SMIL30MimeModules-Mime |
| Internet Media Type | text/smil |
XML-based markup language for multimedia presentations. See https://www.wikidata.org/wiki/Q1072180 |
| Magic numbers | RFC 4536 published May 2006 – IANA.org Regulations Magic Numbers: “There is no single initial byte sequence that is always present for SMIL files.” Section 4 of RFC 4536 document gives some guidelines for recognizing SMIL files. | |
| Pronom PUID | fmt/205 |
See http://www.nationalarchives.gov.uk/PRONOM/fmt/205. |
| Wikidata Title ID | Q1072180 |
XML-based markup language for multimedia presentations. See https://www.wikidata.org/wiki/Q1072180 |
| General |
Previous Versions of SMIL: Synchronized Multimedia Integration Language (SMIL) 1.0 Specification, released in June of 1998 and was the “first version of SMIL integrating a set of independent multimedia objects into a synchronized multimedia presentation.” Synchronized Multimedia Integration Language (SMIL 2.0) - [Second Edition], released in January 2005, extending the functionality of SMIL 1.0, “SMIL 2.0 deprecates a small amount of SMIL 1.0 syntax in favor of more DOM friendly syntax.” Also, SMIL 2.0 updated the meta information functionalities with the introduction of the <metadata> element. Synchronized Multimedia Integration Language (SMIL 2.1), released in December 2005, was a new version built on top of SMIL 2.0 that introduced some new modules as well as new profiles built using SMIL 2.0 modules. Synchronized Multimedia Integration Language (SMIL 3.0), released in December 2008, built on top of SMIL 2.1, added three new profiles and two modules. Each version provides a comparison to the previous version, detailing changes or updates. |
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| History |
W3C announced the Synchronized Multimedia Integration Language (SMIL) first working draft in November 1997, enabling authors to create television-like content for the Internet using a simple text editor. SMIL was developed by the W3C Synchronized Multimedia (SYMM) Working Group, including industry members from Digital Equipment Corporation, Lucent/Bell Labs, Microsoft, Netscape, Philips, RealNetworks and The Productivity Works, and leading research organisations such as Columbia University, CWI and INRIA. The SYMM Working Group’s mission is to continue to extend the functionalities started in SMIL 1.0, investigate proposals, and potentially develop new ones. Synchronized Multimedia Integration Language | W3C Working Draft specifies “SMIL allows integrating a set of independent multimedia objects into a synchronized multimedia presentation” and list features of SMIL presentation. The document also covers SMIL’s relation to XML, syntax, and file layout. Synchronized Multimedia Integration Language (SMIL) 1.0 Specification, released in June of 1998. See notes for more information on previous versions of SMIL. |
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