Getting to Know Digital Video - dummies

By Keith Underdahl

Human beings experience the world as an analog environment. When we take in the serene beauty of a rose garden, the mournful song of a cello, or the graceful motion of an eagle in flight, we are receiving a steady stream of infinitely variable data through our various senses. Of course, we don’t think of all these things as “data” but rather as light, sound, smell, and touch.

Computers are pretty dumb compared to the human brain. They can’t comprehend the analog data of the world; all computers understand are yes (one) and no (zero). In spite of this limitation, we force our computers to show pictures, play music, and display moving video; infinitely variable sounds, colors, and shapes must be converted into the language of computers — ones and zeros. This conversion process is called digitizing. Digital video — often abbreviated as DV — is video that has been digitized.

To fully understand the difference between analog data and digital data, suppose you want to draw the profile of a hill. An analog representation of the profile (shown in Figure 1) would follow the contour of the hill perfectly, because analog values are infinitely variable. However, a digital contour of that same hill would not be able to follow every single detail of the hill, because, as shown in Figure 2, digital values are made up of specifically defined, individual bits of data.

Figure 1: Analog data is infinitely variable.

Figure 2: Digital data contains specific values.

Comparing analog and digital video

Digital recordings are theoretically inferior to analog recordings because analog recordings can contain more information. But the truth is that major advances in digital technology mean that this really doesn’t matter. Yes, a digital recording must be made up of specific individual values, but modern recordings have so many discrete values packed so closely together that human eyes and ears can barely tell the difference. In fact, casual observation often reveals that digital recordings actually seem to be of a higher quality than analog recordings. Why?

A major problem with analog recordings is that they are highly susceptible to deterioration. Every time analog data is copied, some of the original, infinitely variable data is lost. This phenomenon, called generational loss, can be observed in that dark, grainy copy of a copy of a copy of a wedding video that was first shot more than 10 years ago. However, digital data doesn’t have this problem. A one is always a one, no matter how many times it is copied, and a zero is always a zero. Likewise, analog recordings are more susceptible to deterioration after every playback, which explains why your 1964-vintage Meet the Beatles LP pops, hisses, and has lost many of its highs and lows over the years. Digital recordings are based on instructions that tell the computer how to create the data; as long as it can read the instructions, it creates the data the same way every time.

Whether you are editing analog or digital material, always work from a copy of the master and keep the master safe. When adding analog material to your project, the fewer generations your recording is from the original, the better.

When you consider the implications of generational loss on video editing, you begin to see what a blessing digital video really is. You’re constantly copying, editing, and recopying content as you edit your movie projects — and with digital video, you can edit to your heart’s content, confident that the quality won’t diminish with each new copy you make.

Warming up to FireWire

FireWire is one of the hot new technologies that makes digital video so fun and easy to work with. FireWire — also sometimes called IEEE-1394 or i.LINK — was originally developed by Apple Computer and is actually an interface format for computer peripherals. Various peripherals including scanners, CD burners, external hard drives, and of course digital video cameras use FireWire technology. Key features of FireWire include

  • Speed: FireWire is really fast, way faster than USB or serial ports. FireWire is capable of transfer rates up to 400Mbps (megabits per second). Digital video contains a lot of data that must be transferred quickly, making FireWire an ideal format.
  • Mac and PC compatibility: (What a concept.) Although FireWire was developed by Apple, it is widely implemented in the PC world, as well. This has helped make FireWire an industry standard.
  • Plug-and-play connectivity: When you connect your digital camcorder to a FireWire port on your computer (whether Mac or PC), the camera is automatically detected. You won’t have to spend hours installing software drivers or messing with obscure computer settings just to get everything working.
  • Device control: Okay, this one isn’t actually a feature of FireWire, it’s just one of the things that makes using FireWire really neat. If your digital camcorder is connected to your computer’s FireWire port, most video editing programs can control the camcorder’s playback features. This means you don’t have to juggle your fingers and try to press Play on the camcorder and Record in the software at exactly the same time. Just click Capture in a program like iMovie or Pinnacle Studio, and the software automatically starts and stops your camcorder as needed.
  • Hot-swap capability: You can connect or disconnect FireWire components whenever you want. You don’t need to shut down the computer, unplug power cables, or confer with your local public utility district before connecting or disconnecting a FireWire component.

All new Macintosh computers come with FireWire ports. Some — but not all — Windows PCs have FireWire ports as well. If your PC does not have a FireWire port, you can usually add one using an expansion card. Windows 98 and higher include software support for FireWire hardware. If you’re buying a new PC and you plan to do a lot of video editing, consider a FireWire port a must-have feature.

All digital camcorders offer FireWire ports, as well, although the port isn’t always called FireWire. Sometimes FireWire ports are instead called “i.LINK” or simply “DV” by camcorder manufacturers who don’t want to use Apple’s trademarked FireWire name. But rest assured, all digital camcorders have a FireWire-compatible port. FireWire truly makes video editing easy, and if you are buying a new camcorder, you should strongly consider buying a camcorder that includes a FireWire port.