And so we move on to the final stop on our tour of the elements that make up our online communications. The subject of this final posting is video. What contribution can video make? In which situations is it less effective? How is video best delivered online?
What video is good for
Video excels at depicting real-life events. So, assuming that a particular real-life event is of interest, then if it moves and you can point a camera at it, video really is your medium of choice. As another real bonus, it’s easy to record audio at the same time in perfect synch, meaning video is really two media elements packaged as one.
Because the visual and audio content of a video is constantly changing, it attracts and maintains attention. Just think how your eye gets drawn to the TV, even with the sound off.
Video is perfect for showing pre-recorded material, but can also be used to deliver live video feeds, through simple webcams or top-end video conferencing services, such as telepresence.
Video can do more than show what a camera can capture; it can also be used as a simple, alternative means for displaying a wide range of multimedia material, such as software sims, narrated PowerPoint presentations, scenes from virtual worlds or Flash animations.
When video is not so suitable
Video is not self-paced. Although you may have the facility to rewind and fast forward recorded video, you cannot control the speed at which the audio content is delivered. With a live video stream, you have no control at all. Because video is not self-paced, it provides the viewer with less opportunity for reflection or note-taking.
Because video is the most bandwidth-hungry of all media elements, users with bandwidth constraints will be unable to take advantage. And in those situations where two-way live video is required, each participant must have a webcam installed.
Clearly video has little to offer when the content is not visual in nature or when there is little movement in the visual content.
Optimising video for online delivery
Because online video is typically displayed in a small window, it works best when the subject matter does not contain a lot of fine detail. In years to come, when bandwidth ceases to be much of an issue, then this constraint will drop away and online high-definition playback will be normal.
With pre-recorded video, it makes sense to organise the content into short modules which users can access easily from a menu. In YouTube, you can organise a collection of modules into a playlist with a single URL.
Video can be captured on a portable recording device (a camcorder, a stills camera with a video capability or a phone) or directly into a computer via a webcam. In the case of the latter, it pays to frame the subject carefully and make sure it is well lit. If your material is only ever going to be played back online, there is little to be gained by recording in high definition.
In anything other than live situations, you’ll benefit from carrying out some editing of your content. There are free tools such as Microsoft MovieMaker and Apple’s iMovie, very capable low-cost versions of professional tools, such as Adobe Premiere Elements and, of course, the professional tools, such as Avid, Adobe Premiere and Final Cut Pro. In most cases, the free and low-cost tools are more than adequate for the simple editing required when creating online video.
Note that, to accommodate those users who have a visual or auditory impairment, you need to provide a transcript of any important video material.
Combining video with other elements
Video obviously combines well with audio, because this allows the eye to concentrate on the visual material, while the verbal content is communicated aurally. It would not work to display text alongside a video; if audio really is not feasible, perhaps because users’ computers are not fitted with sound cards, then the text should be superimposed on the video, like sub-titles.
Video does not combine well with a second visual source. Whichever is not the primary focus of attention should be turned off or removed.
How videos are represented online
Video quality is determined by the resolution (the number of pixels making up the image) and the frame rate. As a guide, standard definition TV is displayed at 720×576 / 25 frames per second (fps) in Europe or 720×480 / 30 fps in the USA. High definition has between a two and five times better resolution. Digital audio quality is determined by the sample resolution and frequency and the number of channels (see the audio posting).
- MP4 (MPEG-4 / H.264) – user must have Adobe Flash or Apple Quicktime installed
- FLV (Flash video) – user must have Adobe Flash installed
- WMV (Windows Media Video) – user must have Windows Media Player installed
The trend is towards Flash video, not least because this is what YouTube uses. For delivery on iPods and similar devices, MP4 is the most common.
Video can be delivered in such a way that it can be downloaded by the user and played offline, or streamed contiinuously to the user with no opportunity for download. To accommodate streaming, a streaming media server is required. As an example, YouTube streams its video, whereas iTunes makes videos available for download.
Most video editing software will be able to export in a wide variety of compression formats.