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- Adding multimedia to your
Longdesc
A
longdesc (or "long description") file is used to describe images that are too complex to summarize in alt text. Rather than including the description in the CNXML markup, the full, detailed description is contained in a separate file that is linked from the
media element. This allows you to describe the image in as much detail as necessary without needing to keep the description short. A longdesc file:
- Can be any file type, though a basic text-only HTML file is most appropriate.
- Can be loaded into a Connexions module like any other image or resource file.
- Is not a replacement for alt text, but instead is a chance for the author to elaborate on alt text.
- Is only necessary when the image is so complicated that an alt text description is not sufficient to describe it.
The following example shows how to link to a longdesc file titled
earnings_report_desc.html :
<media id="longdesc_example"
alt="An earnings graph showing steady growth of 6% over the past two quarters."longdesc="earnings_report_desc.html"><image mime-type="image/png" src="earnings_report.png" /></media> In this example,
earnings_report_desc.html would most likely be a simple text file describing the details of the chart, including the data points, overall trends, and any other relevant information. While the alt text describes "steady growth of 6% over the past two quarters," the longdesc file can talk about specific features of the chart, such as a dip that coincided with a recent merger or a spike that represented a major product release. A screen reader user would have the option of following this link in order to get a detailed understanding of the data that would otherwise be conveyed and understood by sighted users through visual information.
Remember, longdesc files are not common, and are usually only used when the media element contains important visual information that is too complex and/or detailed for alt text.
Captioned video and audio transcripts
Captioning is another important consideration when dealing with video content. Users who are hearing impaired may not be able to understand all of the information being conveyed in a video, limiting their access to the material being described. This can be addressed by submitting videos that are captioned, allowing those users to read along with the spoken materials. If you are not able to caption your videos, another option is to include audio transcripts of the materials as a module resource that can be easily accessed using a link. While there are no specific tools or standards for providing this type of content, the important thing to remember is to make it as easy as possible for as many people as possible to access the information you are trying to communicate.
Once you've attached your multimedia files to your module, the next step is to embed the media files in your content. This can be done by using the
<media> element.
Source:
OpenStax, Ideas and tools for improving connexions modules and collections. OpenStax CNX. Mar 22, 2010 Download for free at http://cnx.org/content/col11184/1.2
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