Skills for Access

Why this is important

Providing captions enables media that contains spoken or other audio information important to understanding the media's content (for example on- or off-screen dialogue, sound effects, or background music) to be accessible to anyone who has difficulty hearing, or is unable to hear, the media soundtrack. Any content intended for playing in Real Player must as a result offer captions to be optimally accessible for these users.

General Principles

Realmedia (.rm) video files use RealText to provide caption files, Synchronised Multimedia Integration Language (SMIL) to combine the caption file with the media file, and a RAM file as the actual file to be referenced on a web page. The Real Text caption file and SMIL file can be created in a text editor or caption-authoring software such as MAGPie.

NB: We have provided general advice on captioning in a separate How To: Provide text equivalents for audio - general advice on captions.

Before you continue

The advice on this page helps you avoid introducing a specific accessibility barrier, but it's not a magic formula. To avoid attempting to follow a technical solution that is not appropriate to the resource and its intended purpose, you need to know the context in which the multimedia resource is being used:

1. The purpose or aim of the multimedia resource in question, and whether it is being used to supplement another resource in the learning environment, or whether its use is required by students.
2. The target audience, their knowledge and expectations, and the type of browsing and assistive technology that they may be using.
3. Whether the information and experiences provided by the multimedia technology are already available in an equivalent, alternative form.

For more background on this approach, see our Guide to the use of multimedia in accessible e-learning.

Technique Details

The outline procedure of creating and making available a captioned Realmedia video file is as follows:

Step 1: Create a RealText file containing the caption text plus timestamp detail (the time at which each specific piece of caption text is displayed - essential for synchronised captions). A RealText file is a simple text file, extension .rt. Other attributes can also be specified in the RealText file, including size of the window containing the captions, appearance of caption text and nature of caption display (for example whether scrolling or 'ticker' style captions are required).

To obtain timestamp detail, you must play the video, pausing and noting the time at which each caption will appear. If you have a transcript file already, the time taken and effort required to create captions is reduced, as you can then focus on splitting the transcript text into appropriate captions, and applying a timestamp to each. If you don't have a transcript you'll have to create this first by playing the video and writing down spoken and non-spoken sound information.

NB If the RealText file has been created in MAGPie, it will need some editing to remove some code that is created automatically. The WebAIM RealPlayer captioning tutorial provides details.

Example 1 shows a sample of a RealText file, incuding caption text and timestamp information, used to create the captions for a Real video clip.

<window type="generic" extraspaces="use" wordwrap="true" width="320"
duration="0:01:21.31" bgcolor="#000000">

<time begin="00:00:00.00"/><clear/><font face="Verdana">
<font size="3">
<font color="#FFFFFF"><font bgcolor="#000000">
<b>"Access for All" came about 
<br/>because obviously DDA

<time begin="00:00:03.57"/><clear/>and SENDA were both 
<br/>introduced and that

<time begin="00:00:07.59"/><clear/>accompanied a perceived 
<br/>inaccessibility of multi-media.

<time begin="00:00:11.02"/><clear/>The project 
<br/>specifically is looking at

<time begin="00:00:14.50"/><clear/>the requirements
<br/>for users and learners

<time begin="00:00:16.52"/><clear/>and researchers 
<br/>who have accessibility

Example 1: Sample of RealText file.

Step 2: Create a SMIL file to combine the RealText caption file with the RealMedia video clip being captioned. This can be created in a text editor, or again using software such as MAGPie. It contains references to the media and caption files, plus meta-information about the clip, and information on relative layout of the media clip and captions.

Example 2 shows a portion of the SMIL file used to combine the RealText file shown in Example 1 with a Real Video clip.

<smil xmlns="http://www.w3.org/TR/REC-smil">

<head>
<meta content="Clip 1: Captioned Real Video" name="title"/>
<meta content="Skills for Access" name="author"/>
<meta content="(c) 2005 - Skills for Access" name="copyright"/>

<layout>
<root-layout width="330" height="335" background-color="black"/>
<region top="5" width="320" height="240" left="5" background-color="black" id="videoregion"/>
<region top="245" width="320" height="80" left="5" background-color="black" id="textregion"/>
</layout>
</head>

<body>
<par>
<video region="videoregion" src="/media/rlvidq1.rm"/>
<textstream region="textregion" src="/media/rlvidq1.rt"/>
</par>
</body>

Example 2: Sample of SMIL file.

NB If the SMIL file has been created in MAGPie, it will need editing to remove some code that causes problems for some versions of Real Player. The WebAIM RealPlayer captioning tutorial provides details (see Related Sites on this page).

The process of successfully synchronising captions with the movie will be an iterative one. You'll probably have to spend some time adjusting time-stamps and the text displayed at each timestamp. Just keep editing the caption file, recombine it with the video and checking over until everything is satisfactory.

Step 3: Make the captioned file available for playing on a web page. To do this, a RAM file must be created - this is a file that simply contains a reference to the SMIL file, and can safely be assumed will open in Real Player. This step is necessary to ensure that the SMIL file opens in Real Player - as providing the SMIL file directly on the web page may result in it opening in QuickTime or Windows Media Player, depending on a user's settings).

To make the captioned clip open in a stand-alone player (the most accessible way of providing your video), the HTML is simple - just a link to the RAM file using the HTML <a> element. Clip 1 is an example of a captioned Real video clip, which uses the Real Text file and SMIL files shown in Examples 1 and 2:

If you plan to embed the media file, the HTML code requires using the (non-standard) <embed> element to contain the reference to the RAM file, within an <object> element. If the captioned file is to be embedded in the web page, the HTML of the web page will also require to embed controls for the media player's controls, if being provided (stop, play etc.)

The non-captioned Realmedia file can also be made available on the web page, offering users a choice of captioned and non-captioned media.

The above is an outline of the captioning process, but for a detailed, step by step tutorial on how to caption a Real video file, we recommend WebAIM's tutorial on RealPlayer Captioning.

Testing

The process of creating an appropriately time-stamped caption file should ensure that captions are synchronised appropriately with the video clip. However, it's always a good idea to check that your captions are displayed and synchronised appropriately in Real Player, in as many different platforms as possible, by playing the captioned file with audio turned on. This way, you can detect any clear inaccuracies, missing content or problems with synchronisation.

When captions are provided via a SMIL file, they should display automatically when played in Real Player. However, to, make sure captions appear when available, in Real Player 10, select Tools (View in older versions of Real Player), then Preferences, then Content. In the Accessibility section of the control panel that appears, then select the checkbox 'use supplemental text captioning when available.'

It would also be worthwhile obtaining feedback from end users, particularly people who are deaf or hard of hearing - although they, of course, will be unlikely to know whether the captions are a true reflection of the audio content of the media clip.