Web Design in a Nutshell, 3rd Edition

Basic Digital Video Concepts

The following is a list of aspects of digital video that can be manipulated with standard video-editing software. It is important to be familiar with these terms so you can create video optimized for web delivery.

Movie length

It’s a simple principle: limiting the length of your video clip limits its file size. Videos longer than a minute or two may cause prohibitively long download times. If you must serve longer videos, consider one of the streaming video solutions.

Frame size

Obviously, the size of the frame has an impact on the size of the file. “Full-screen” video is 640 × 480 pixels. The amount of data required to deliver an image of that size would be prohibitive for most web applications. The most common frame size for web video is 320 × 240 pixels. Some producers go as small as 160 × 120 pixels.

Frame rate

The frame rate is measured in number of frames per second (fps) . Standard TV-quality video uses a frame rate of approximately 30 frames per second to create the effect of smooth movement. For the Web, a frame rate of 15 or even 10 fps is more appropriate and still capable of producing fairly smooth video playback. For “talking head” and other low-motion subjects, even lower frame rates may be satisfactory. Commercial Internet broadcasts are routinely done as low as 0.5, 0.25, or even 0.05 frames per second (resulting in a slideshow effect rather than moving video).

Quality

Many video-editing applications allow you to set the overall quality ...