Since the development of broadcast cameras and television sets in the early 1940s, video has slowly become more and more a part of everyday life. In the early 1950s, it was a treat simply to have a television set in one’s own home. In the 1960s, television brought the world live coverage of an astronaut walking on the moon. With the 1970s, the immediacy of television brought the events of the Vietnam War into living rooms. In the 21st century, with additional modes of delivery such as satellite, cable and the Internet, video has developed into the primary source of world communication.
However, while the television set itself provided a cool fire around which many families in the 20th century sat, today many people choose to watch their favorite TV shows and movies on their computers and mobile devices. Without the anchor of the older delivery medium, video content has become king and websites such as YouTube and Vimeo, and subscriber-based services such as Netflix, Hulu and Amazon, have become a major part of the video fabric of our on-the-go lives.
Video Evolution
Just as the use of this medium has changed over the years, so has its physical nature evolved. The video signal started as analog and has developed into digital with different types of digital formats. When television was first created, cameras and television sets required a great deal of room to house the original tube technology of the analog world. In today’s digital society, camera size and media files continue to get smaller as the quality continues to improve.
For example, when this book was first published, High Definition was becoming the format of choice. Now the industry is creating programming in Ultra High Definition (4K), which has over twice the resolution of High Definition. This expansion in resolution and ease of use has caused many producers to choose the digital route over shooting on film for their projects.
Although the equipment has changed, some of the processes involved in the origination of the video signal have remained the same. This makes the progression of video from analog to digital not only interesting to study, but helpful in providing a foundation of knowledge upon which the current digital video world operates. 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.
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.
Figure 1.2
Analog Videotape Recording vs Digital Video Production
With the advent of digital, the primary system for signal reproduction has become solid-state electronics, incorporating computers, servers and digital cards. This change has created a computer file-based system, rather than the taped-based mechanical system of the analog era. File-based systems allow random, or nonlinear, access to information without respect to the order in which it was produced or its placement within the storage medium (Figure 1.2).
While most cable companies, broadcast stations, Internet companies, and production or post production facilities create, edit and transmit video signals using a digital file-based system, some facilities still have older videotape machines for inclusion of legacy (analog) content.
About This Book
To create a complete picture of the video process—and answer the question “How does video work?”—this book begins by examining the analog video signal. Digital video technology is a direct evolution from the analog system. Having the knowledge of the analog system provides a firm foundation before moving into a discussion of digital, and how video works today in the new age of digital distribution.
While this book is designed to cover the process of creating a video signal, storing it, and transmitting it in a professional environment, the same information and concepts apply to any video tool, including consumer equipment.
