Types of Digital Media II

Images

Images have a unique power to instill emotions and affect attitudes in ways that textual information cannot. Images also take advantage of our visual ability to decode complex and sophisticated information, allowing us to quickly and automatically make sense of it while organizing it under different categories. It is easy to see how digital images can be a tremendous asset in designing and delivering Web-based instruction.

Sometimes a powerful instructional image is conveying complex information that is most effectively represented as graphic information, and sometimes it is just a pretty picture. Either case may be appropriate or even vital to your course content, but in the case of images that contain information significant to the instruction, you will need to provide a textual description of the content.

As part of the range of content that can be contained in an image, often digital images will be of textual information, but this is not the same as digital text. A quick and easy way to check if you’re dealing with digital text or a digital image of text is to try and select the text on your screen and copy it to a word processing program or text editor. If you can copy the text into the word processing program or text editor, you are dealing with digital text. If you can’t copy the text, you may be dealing with an image of text.  If it is an image of text, then an "alt tag" must be included.

Audio

Digital audio can be stored in several different formats and with a wide variety of quality and file size. Regardless of the specific digital audio format used, the strategy for providing access remains the same: provide a transcript.

Audio information can convey many types of information, from verbal dialogue to music and sound effects. Obviously, verbal dialogue can be transcribed into text, but transcribing music and sound effects is not as easy to do. Typically, if you can not provide a direct transcription, you can try to describe the nature/effect the music or sound effect is trying to create. In general, the basic rule of thumb is to provide a transcript of the spoken dialogue and other meaningful audio content for individuals who may be deaf or hard of hearing.

Unlike digital image files, certain audio file formats will allow you to permanently associate textual information with the audio content. In this way, the audio file always has the textual description included no matter where you copy or move the file. The problem with this is that the playback device or software must provide a method for viewing the textual description.

Some common audio files that support the permanent association of textual descriptions are MP3 (.mp3), MP4 (.mp4), Apple Audio Codec (.aac), Quicktime Audio (.mov), and the Apple proprietary formats (.m4a, .m4b, .m4v). It is important to know which file format your audio information is in, and how to associate textual information with that file.

Remember that even if you embed the transcript of an audio file in the meta-information (ID3 tags) of that digital file, you should also provide the text transcript as a separate download. If a student is completely deaf (as opposed to having a degree of partial hearing loss), they may prefer to only have to download the smaller text file rather than the much larger audio file where the transcript is embedded in the ID3 tags.

Finally, remember that producing good quality recordings can also help increase the accessibility and usability of audio files for individuals who are hard of hearing (and those without hearing problems). If the overall quality of an audio recording is poor, AT will have an even more difficult time with the information.

Video

Digital video information typically includes audio, which again needs to be transcribed. However, because it is video, the text transcript must be delivered synchronously with the corresponding dialogue as it is spoken on screen. This is called captioning.  There are two types of captioning: open and closed. Closed Captions are the captions that you can turn on and off, assuming that you know how to work your television’s remote control and/or know where to locate this in your web-based video viewer.  Note that in YouTube, simply click on the CC on the toolbar under the video. Open Captions are the captions that are permanently turned on, similar to foreign language subtitles.

There is an important distinction between captions and subtitles: subtitles provide a translation of dialogue, while captions provide a textual indication of all significant audio information, including sound effects and music. For accessibility concerns, subtitles are not equivalent to captions because subtitles do not convey all of the significant audio information of the video.

Complex Digital Media

Complex media refers to digital media formats and systems that can contain multiple media types at the same time and/or provide means for user interaction with the content. Complex media can be a single digital file or a system that coordinates multiple digital files being exchanged between the instructor and students. HTML and PDF files are common examples of complex media files that can support a variety of different media types. TalonNet is an example of complex media delivery system, providing a variety of ways to organize and deliver digital content and offering multiple methods for interaction with the content and other users.

Typically, complex digital media is an assemblage of discreet media files such as text, images, audio, and video. By following the best practices for creating these individual digital files, you can help ensure the accessibility and usability of the information when it is presented as part of a complex document or digital media system. In addition, it is important to become familiar with any built-in accessibility tools that are included in whatever complex media file format or system you use.
In addition to ensuring the accessibility of the discreet media assets used in a complex media file or system, it is critical to ensure accessibility of the various interactive aspects to ensure that they are compatible with different AT.

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