Module 7. The technical foundations of digital video

What is video?

Video is a series of images flashed in such rapid succession that your eye interprets the changes between successive images as motion. Traditional film works in this manner. Every frame in a 35mm film--the standard format for cinema--contains an image as well as a visual representation of the soundtrack for that film (see Figure 7.1). The soundtrack which would be read by a special device and translated into sound, much like the phonograph would read the grooves of a vinyl record and used that information to produce sound. This soundtrack used to be analog although sometimes an optical film track (Figure 7.2) is used.

Video vs. animation

From a viewer's perspective, digital video and digital animation both are experienced as moving images. However, video is generally recorded whereas animations are generated. In producing videos, you use a camera to "capture" events that unfold in time. Usually, these events occur in the everyday, physical world, in which case fidelity becomes a consideration. For example, we would want that our footage faithfully records colors and lighting conditions. In this regard, video is similar to film.

The boundaries between contemporary TV, film, video, and animation are hard to define: This is because video can be viewed on different display devices and stored using different media substrates. Media are not always distributed in the same substrate they were recorded in. A video can be shared over Internet, saved onto a portable drive, recorded onto a DVD, or even transferred back into an analog format like VHS. Video can be viewed on computer monitors, television sets, and cinema screens. Film can be transferred to video, video and computer animations can be printed on film stock, films and video are broadcast on TV, TV and videos can be streamed online, and so forth. It helps to remember that even if video is recorded using one substrate (such as digital magnetic tape, or analog cellulose-based film), it can be edited on machine that uses magnetic disks, and then distributed as a DVD, a Blu-ray DVD, a VCD, or as digital file on your computer.

Streaming digital video

In the early days of digital video, Real Media was a popular format for streaming video. Streaming is a way of viewing video that allows you watch a video without downloading the entire file. Instead, your computer downloads parts of the video as they are needed. You can save a lot of time that way. The Real Media video format is now largely obsolete, and newer formats for streamed video are more commonplace. Nowadays, most people who own a smartphone often will watch streaming video.

Digital video compression

Compression is very important in video, as you have already seen, but detailed discussion of video compression can become extremely technical. Basith & Done (1996) give a useful introduction to video compression. The important thing to note is that compression can produce unwanted artifacts and can slow down the production process, and that there are commonly used compression standards, such as MPEG-1, MPEG-2, and MPEG-4. If you want to learn advanced concepts on video compression, see Rui del-Negro (n.d.). Although these articles are somewhat older, the basic issues described remain current. What has changed are standards and available technologies for video. High-definition (HD) and other newer formats (such as 4K) are now available both on Web video platforms (such as YouTube and Vimeo) and for broadcast TV.