Synchronized Multimedia Integration Language

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Synchronized Multimedia Integration Language (SMIL)
File extension : .smil
MIME type : application / smil + xml
Developed by: World Wide Web Consortium
Type: Markup language

The Synchronized Multimedia Integration Language ( SMIL ; pronunciation like smile ) is an XML- based standard developed by the World Wide Web Consortium (W3C) for a markup language for time-synchronized, multimedia content. SMIL enables the integration and control of multimedia elements such as audio, video, text and graphics in websites; SMIL files can be linked to Java applets and servlets or CGI scripts and thus access a database, for example. The file extension .smi or .smil is used.

SMIL example with subtitles, graphic overlays, text snippets and an audio track.

Areas of application

SMIL applications can be used in many ways. They are particularly suitable for use cases in which videos enriched with additional media are to be played back. In addition to the examples listed here, other areas of application are conceivable. Particularly in connection with SVG and ECMAScript , application possibilities open up that correspond to those of Adobe Flash and other rich Internet applications .

Computer-aided teaching

As an example, computer-aided teaching can be enhanced with SMIL. In this case, it is very helpful to display time-controlled texts and additional information about a video. For example, the video can automatically pause at important points in order to give the viewer the opportunity to take in the relevant information in peace. The viewer can thus determine the learning speed himself. In addition, an interactive hypermedia structure can be set up using links in the video or additional media. This enables the viewer to determine not only the learning speed but also the learning direction himself. Until now, this was not possible with conventional linear videos. In addition to the advantages for the viewer, there are also advantages for the author. In this way, he can set up a SMIL presentation in a modular manner and thus achieve a higher degree of reuse, which enables time and cost savings. In addition, less storage space is required due to higher reuse.

Video cut

Thanks to the timing and cross-fading functionalities, SMIL can also be used as a cutting tool. The author can specify the beginning, the end and the active duration of a video or other element for each frame. Small workarounds can even "cut" a long linear video into smaller pieces without actually changing the video file. In contrast to professional video editing software, the information about cut marks and other properties only require a few kilobytes . SMIL offers a variety of cross-fading effects , which can also be changed with additional information. It is also possible to display text and images without further ado. These can be changed or exchanged in size and position as required. In addition, SMIL can contain additional audio tracks . These and all other elements can be selected automatically, depending on the user language, without user intervention. Here too, individual elements can be reused. In addition, picture-in-picture or even picture-by-picture displays are possible. The biggest advantage is that the cut and edited videos do not have to be time-consuming to render into binary format. Every change can be viewed and published immediately.


The main characteristics of SMIL include:

  • Specification of layout and synchronization;
  • Adaptation to the transmission bandwidth;
  • Selection of different language versions;
  • Adaptation to different screen resolutions and color depths;
  • Support of hyperlinks;
  • easy to learn, similar to HTML.


The current version to be used is SMIL 3.0 .

SMIL 1.0
The W3C published the first official recommendation for SMIL 1 in June 1998 .

SMIL 2.0
The official recommendation for SMIL 2 was released in August 2001. Its non-normative previous version, the Boston Draft , has already been used for new implementations ( IE5.5 ).

In addition to a few extensions, SMIL 2 mainly introduced fundamental structural changes with a modularization. The modularization makes it possible to integrate parts of the specification within other (XML) formats ( namespace mechanism ), or to implement a defined subset of the specification.

With version 2, the animation elements were taken from the vector graphic format SVG and expanded. An independent animation (as well as the fading in and out of video content) was not previously planned in SMIL. From version 1.1, SVG also explicitly provides for the integration of its own format by SMIL.

SMIL 2.1
The final version of SMIL 2.1 has been available since December 2005. This version contains a small number of enhancements that mainly affect use in mobile devices with multimedia messaging services .

SMIL 3.0
SMIL 3.0 was submitted as a W3C Working Draft on December 21, 2006. The final version was published on December 1, 2008. Version 3.0 extends the functionality of SMIL 2.1 and replaces this version as a W3C recommendation.


SMIL is text based and an application of XML. The basic syntax defines the layout of the multimedia presentation; the timing and interaction with the presentation is easy to learn. In principle, SMIL files can be created or modified with any text editor .

The creation of SMIL is supported by various applications:

  • Adobe's GoLive !
  • Allaire's HomeSite
  • Oratrix GRiNS Editor
  • Macromedia Dreamweaver in conjunction with the G2 Objects
  • LIMSee 2.0 and LIMSee 3.0
  • Kino , free video editing program for Unix

While SMIL1 is a stand-alone file format, SMIL2 can also be integrated into other file formats such as XHTML or SVG . The namespace mechanism of the XML format is used for this, on which all the formats mentioned are based.

So far, SMIL has not found any concrete and successful application in industry. SMIL was first widely used with HD DVD .


Ambulant is an open source project from the Centrum Wiskunde & Informatica (CWI) in the Netherlands . Ambulant is the only player that fully supports SMIL 2.1. Outpatient is available for Windows , macOS , Linux and Pocket PCs with Windows CE .

The RealPlayer plays SMIL files from version 8. The player also understands RealText in SMIL files. This enables further formatting and time-dependent processes in SMIL presentations. RealPlayer also allows some specific extensions that only it can understand. An example of this is "rp: BackgroundOpacity" which enables transparent graphics or videos.

HelixDNA Client
The streaming media company RealNetworks offers the player Helix DNA Client for Linux as open source software under the RealNetworks Public Source License .

Apple's QuickTime Player supports only part of the entire SMIL 1.0 language range.

designation Video Audio photos operating system
Outpatient DivX, MJPEG MP3; Ogg Vorbis (streamed) JPEG, PNG, GIF macOS , Windows , Linux
QuickTime QuickTime, MPEG 4 (streamed) MP3, AIFF; RealAudio (streamed) JPEG, PNG, GIF, Flash macOS , Windows
RealPlayer MPEG-2, MPEG-4; RealVideo (streamed), MJPEG MP3; RealAudio (streamed) JPEG, PNG, GIF, Flash macOS , Windows , Linux , Palm OS , Symbian OS , Windows Mobile
Helix Player RealVideo (streamed), unknown RealAudio (streamed), unknown unknown Linux
totem unknown unknown unknown Linux
Windows Media Player unknown unknown unknown Windows
Media Player Classic unknown unknown unknown Windows
X-SMILES unknown unknown JPEG, SVG Windows
Grin player unknown unknown unknown Windows
Smile unknown unknown unknown Windows


Web links

Individual evidence