Digital Video

We've all heard the term "digital." Most of us are by now familiar with digital telephones and digital CD's. The cellular telephone industry has been bombarding us with visions of "crystal clear" digital transmissions for years. Most of us have seen or been introduced to the digital camera, which, in conjunction with a computer, allows us to shoot and view a still image without film. "Digital video" is, not surprisingly, the same technology applied to a stream of still images designed to produce a "motion picture" effect. This material should be used as directed to complete any Review Questions Sheet that is assigned.

    What is so great about digital video? Why a new technology? After all, traditional analog video formats, such as the familiar VHS format, seem to work just fine. However, one of the main drawbacks to video tape, is the loss of quality that is experienced when the original tape is edited. To understand this concept, let's use the example of copying a CD to audio tape.

    Your CD's contain digital music files. If your stereo has a cassette player as well, you are able to record the music to an audio cassette tape. However, when the CD is played, it is done through the use of a digital-to-analog (D/A converter) device. The device reads the digital information on the disc and translates it into an analog signal that can be played through the amplifier and into a speaker. This same analog information is sent to the cassette tape recorder which records the information in analog form onto the tape. The transfer causes "signal loss" resulting in a lower quality of audio on the tape. If that tape is then copied and passed along to a friend, then the second copy has even more signal loss and poorer quality audio. The same concept holds true for video tape. The original has to be edited in order to put together a video production. As each section is copied, there is signal loss. This can result in both video and audio degradation. The secret of digital video lies in the way the image is recorded. Instead of  recording an analog waveform (video still picture), digital technology records a long series of "binary code" ("bits"). Since the information is saved in a computer code, there is absolutely no loss of quality if a digital video file is copied. That is...until video compression software is used, but that's another section that will be covered later!

    Digital video is still recorded onto magnetic tape using a camcorder. However, rather than being recorded as analog signals, the video still image is digitized into 0's and 1's and written to magnetic tape. These "binary switches" are either "on" or "off". Then, on playback, the camcorder or deck processes or codes them in a special way to turn them into a video signal. This is very similar to how a computer might record its data onto a floppy disk. The information written includes error correction codes, so that even if some data is missing on playback, it can be reconstructed using these error correction codes so no information is lost.

     But wait! That sounds exactly like how a computer works. Bits and bytes. We all remember those things. Well, that's exactly why digital video technology is so exciting. It brings the world of video production to the ordinary computer owner like you and me. We call this new technology "digital video" or "desktop video" (DTV). It is now possible for us to shoot high-quality videos, download the images to our computers, edit them and manipulate the images in extraordinary ways, add fascinating and engaging special effects and sound,and upload the finished product to a "master" medium such as the VHS tape, CD ROM, or for Internet viewing. We can even play back the videos on our computer monitors as full-screen, full-motion dazzling multimedia events. And we can do this at PC computer system prices, not the high-price "broadcast" suites affordable only by the pros, often costing $100,000 or more.

 

The Digital Video Process

    Desktop or digital video has revolutionized the way that video is recorded, edited and stored. In the days of analog video, it was only possible to create "broadcast quality" video through the use of professional editing suites and workstations costing hundreds of thousands of dollars. This was due to the fact that home VHS recorders and camcorders produced video of lower resolution and inferior quality. Then, once it was copied or edited, the copy was of even more inferior quality that could not compare to the quality produced by major television networks. Digital video has changed all of that.

    Like the advent of desktop publishing in the 1980's, personal computers and desktop video editing suites now allow the production of professional quality video at near-broadcast quality. As the necessary hardware and software become more affordable, many users will have the ability to turn a desktop computer into a complete, professional, broadcast-quality workstation.

    One of the best features of digital video is the flexible output it allows. Video can be taken, captured, edited and output to tape. The same production can be compressed and written (or "burned") to a CD for multimedia use. There is even the capability to use more compression software (like Real Producer) to save media in a "streaming" format for playback on the Internet. One of the biggest impacts in digital video viewing and storage is the widely accepted storage medium called "Digital Video Disc" (DVD). This has taken television to a new "interactive" stage where viewers can view a menu and select information from the disc. It also has eliminated the need to rewind tape!

    All of these digital changes have contributed to a major change in the way that video is produced from start to finish. We refer to this procedure as "video production". All video is produced in two main phases: production and post-production. The "production" phase begins with the script, shooting script, and storyboard. These tools are used to guide the video producer in one of the most important stages of production..."shooting" (capturing video footage on tape).

    Once the production stage has ended, the post-production process begins. The post-production process consists of editing, creating scene transitions, adding effects, and creating titles. Both analog and digital video production follow basically the same production stages. However, the process used for analog video is called "linear editing" and the process used for digital (and some analog) is called "non-linear editing" (NLE).

    Non-linear editing is based on a multi-step process that will be covered in the "non-linear editing" section of this instructional web site. The use of digital equipment and personal computers has dramatically altered the way that video post-production takes place.

    That's a lot to digest....hope it didn't give you indigestion!! Get ready to move into the exciting world of Digital Video!

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