WebAIM - Web Accessibility In Mind

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Re: Multimedia


From: Jared Smith
Date: Mar 31, 2005 10:31AM

In general, these are my recommendations:

- Generic formats, such as mp3, avi, and mpeg can be played by most major
players. You don't have to worry about the end user having a specific
player. However, these formats don't provide as high of compression as
proprietary formats.
- When possible, allow the media to be played in the stand-alone media
player as they are much more accessible to the keyboard and screen readers
than media that is embedded into a Web page.
- Provide a transcript for audio and a transcript and captions for video.
- Windows Media Player, Quicktime, and RealPlayer specific formats will
need distinct links for each media file.
- We use Windows Media Player and Quicktime, as this hits about 99% of
users. If you have a Mac, you have Quicktime. If you have a Windows
computer, you have Windows Media Player. We've used Realplayer in the
past, but their licensing costs for their streaming server are outrageous.
- If you are looking at streaming long sections of audio or video, then
simply linking to a file on your Web server may not be the best approach.
A true streaming server will provide better results, will save bandwidth,
and gives the end user the ability to only download the portions of the
file he/she wants to view. We use Windows Media Server with Windows Server
2003 and Darwin Streaming Server (free) on a G4 Macintosh. We also have a
few videos streaming off of RealServer basic, but they are soon to go away.
- Flash video is very universal, but it is not truly streaming (i.e., the
user must download the entire file to listen to the last few seconds). It
works very well for shorter video segments, but for long videos, it may
not work as well as a true streaming format. There are no standards for
captioning Flash video.

Jared Smith