How Video Works - pág.3

So much of today´s digital technology is the way it is because it evolved from analog.

Analog and Digital

Let´s consider the analog and digital realms. All information from the physical world is analog. A cloud floating by, an ocean wave, and the sounds of a marching band all exist within a spectrum of frequencies that comprise human experience. This spectrum of frequencies can be captured by any number of digital cameras and recording equipment and then translated to any number of digital file types made up of digital data, or zeros and ones, representing the image or sound.

Figure 1.1
From Analog to Digital to Analog

Human beings, however, do not process the zeros and ones of digital data. Eventually that data must be converted back to an analog form so we humans can see and hear it. Even with a digital home receiver and other viewing or listening devices, the zeros and ones of a digital signal must eventually be reproduced as analog for humans to experience it with their sight and sound senses (Figure 1.1).

Signal Reproduction

In the early days of television, video was recorded and reproduced as an analog signal on a videotape machine, which was based on mechanical concepts. The videotape machine moved the videotape along guides and through magnetic heads that recorded or played back the signal. As a result of the videotape moving through a mechanical system, the information could only be recorded or reproduced in the order in which it was created. This made post production of videotape, or the editing and manipulating of content after it was shot, a linear process with no instant access.