Network Working Group P. Hoschka INTERNET DRAFT W3C draft-hoschka-smil-media-type-07.txt June 2001 The application/smil Media Type Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Abstract This document specifies the Media Type for version 1 and version 2 of the Synchronized Multimedia Integration Language (SMIL 1.0 and SMIL 2.0). SMIL allows ntegrating a set of independent multimedia objects into a synchronized multimedia presentation. 1. Introduction The World Wide Web Consortium has issued specificationss which define version 1 [1] and version 2 [2] of the Synchronized Multimedia Integration Language (SMIL 1.0). This memo provides information about the application/smil Media Type. The definition is based on the RFC3023 defining the use of the "application/xml" media type [3]. Before using the "application/smil" media type, implementors must thus be familiar with [3]. RFC 3023 recommends use of the prefix "+xml" for mediatypes that are Expiration Date: December 2001 [Page 1]
INTERNET DRAFT June 2001 based on XML. This document does not follow this recommendation, since the mediatype "application/smil" is already in widespread news, and its definition predates RFC3023 by about two years. This does not preclude future registration of "application/smil+xml", should the need arise. 2. Synchronized Multimedia Integration Language SMIL allows integrating a set of independent multimedia objects into a synchronized multimedia presentation. Using SMIL, an author can 1.describe the temporal behavior of the presentation 2.describe the layout of the presentation on a screen 3.associate hyperlinks with media objects 3. Registration Information To: ietf-types@iana.org Subject: Registration of MIME media type application/smil MIME media type name: application MIME subtype name: smil Required parameters: none Optional parameters: charset All of the considerations described in RFC3023 also apply to the SMIL media type. Encoding considerations: All of the considerations described in RFC3023 also apply to the SMIL media type. Security considerations: SMIL documents contain a construct that allows "infinite loops". This is indispensible for a multimedia format. However, SMIL clients should foresee provisions such as a "stop" button that lets users interrupt such an "infinite loop". As with HTML, SMIL documents contain links to other media (images,sounds, videos, text, ...) and those links are typically followed automatically by software, resulting in the transfer of files without the explicit request of the user for each one. The security considerations of each linked file are those of the individual registered types. Expiration Date: December 2001 [Page 2]
INTERNET DRAFT June 2001 The SMIL language contains "switch" elements. SMIL provides no mechanism that assures the media objects contained in a "switch" element provide equivalent information. An author, knowing that one SMIL player will display one alternative of a "switch" and another will display a different part, can put different information in the two parts. While there are legitimate use cases for this, this also gives rise to a security consideration: The author can fool viewers into thinking that the same information was displayed when in fact it was not. In addition, all of the security considerations of RFC3023 also apply to SMIL. Interoperability considerations: SMIL documents contain links to other media objects. The SMIL player must be able to decode the media types of these media in order to display the whole document. To increase interoperability, SMIL has provisions for including alternate versions of a media object in a document. Published specification: see [1] and [2] Applications which use this media type: SMIL players and editors Additional information: Semantics of fragment identifiers in URIs: The SMIL media type allows to append a fragment identifier to a URI pointing to a SMIL resource (e.g. http://www.example.com/test.smil#foo). The semantics of fragment identifers for SMIL resources are defined in [1]. Magic number(s): none All of the considerations described in RFC3023 also apply to the SMIL media type. File extension(s): .smil, .smi, .sml NOTE: On the Windows operating system and the Macintosh platform, the ".smi" extension is used by other formats. To avoid conflicts, it is thus strongly recommended not to use the extension ".smi" for storing SMIL files on these platforms. Macintosh File Type Code(s): "TEXT", ".SMI", "SMIL", "PNRM" Expiration Date: December 2001 [Page 3]
INTERNET DRAFT June 2001 Object Identifier(s) or OID(s): none Person & email address to contact for further information: The author of this memo. Intended usage: COMMON Author/Change controller: The SMIL 1.0 and SMIL 2.0 specifications are a work product of the World Wide Web Consortium's SYMM Working Group. The W3C has change control over the SMIL 1.0 specification. 5. References [1] "Synchronized Multimedia Integration Language (SMIL) 1.0 Specification", W3C Recommendation REC-smil-19980615, http://www.w3.org/TR/1998/REC-smil/, July 1998. [2] "Synchronized Multimedia Integration Language (SMIL) 2.0 Specification", W3C Proposed Recommendation http://www.w3.org/TR/smil20/ June 2001. [3] M. Murata, S. St.Laurent, D. Kohn E. "XML Media Types", RFC 3023, UC Irvine IBM Tokyo Research Laboratory, simonstl.com, Skymoon Ventures, January 2001. 6. Author's Address Philipp Hoschka W3C/INRIA 2004, route des Lucioles - B.P. 93 06902 Sophia Antipolis Cedex FRANCE Phone: +33 (0)492387984 Fax:+33 (0)493657765 EMail: ph@w3.org Expiration Date: December 2001 [Page 4]
