Digitizing Video
An Introductory Course by Kirk Pearson
Back to Video Course Home Page
Unit One:
Introduction to Digital Video
Unit
Three:
Computer Readiness
Unit
Five:
Video Capture & Editing
Background/History
Most people don't want to take what I'll characterize as a 'how-to' course and spend too much time on history or even a comprehensive background. They want to learn 'how-to'. With that in mind I'll limit this section to just a few basics that should help in understanding concepts discussed throughout the course.
Video footage used to be taken on regular- or super-8 film cameras (we're concerned with more of what's known as the 'consumer' level as opposed to professional or the in-between category, prosumer), and you might have grown up watching films of your childhood on the white screen in the living room as I did. And likewise, you might have watched the film deteriorate, yellow, and ultimately break over the years as the projector clicked away your life.
Some made attempts to salvage their memories on film by having it converted/transferred to video tape. Most imperfections due to time and exposure in the film could only partially be corrected and frankly, this solution was also fated. When video tape came into popularity as a recording/acquisition and distribution media, it wasn't widely understood that since it involved data formatted in magnetized particles on a porous metallic surface, it was susceptible to degradation as the surface eventually soiled, wore out, and crumbled apart. Higher grades of tape, which increased the density of the magnetic particles applied to the substrate, may have offered improved data collection but did not solve the archival pitfalls.
Interesting resources that go into more detail on video tape and related technologies can be found on the Internet. Chronology of Magnetic Recording gives an interesting history of how magnetic recording media and methods came to be. It begins with 1878 and traces important discoveries and inventions up to 1984. Magic of Magnetic Tape more specifically gives a detailed and intriguing explanation of how magnetic tape was created and the people and companies responsible for this. Video Preserves has an easy-to-read explanation of video tape pitfalls and how to take care of your tape media the best you can (until you can better immortalize it through the digitizing process)..
(Many other interesting articles on the history of magnetic video tape and be found by doing a search using the terms 'video tape magnetic' on most Internet search engines; I typically use and would suggest you try Google.)
Since this course is interested primarily in getting you up-to-speed on digitizing video rather than comprehensively chronicle the history of early video practices and technologies, we'll move on to the next section which will introduce important concepts that will help to understand and produce in the digital age.
Terms, Formats, and Concepts
With the computer came new data collection and storage technologies. Video data collected and stored in these technologies is referred to as digital video (DV); those before (like standard VHS videotape) are known as analog. DV continues to evolve and has already seen a number of different formats and coding technologies with respect to both processes and media. (We'll look closer at the hardware side of DV, especially from the consumer/home end of things in the Hardware unit.)
DV as a data type can be formatted in a variety of different ways, each with its own pros and cons. When digital data (video in this case) is created, it is compressed by a technology or component called an encoder. Similarly, when this data is viewed, it is uncompressed by a technology or component called a decoder. Codec is the contraction used to describe these technologies and it simply stands for compressor/decompressor or encode/decode.
There are a number of codecs and the ones you'll most likely see are MPEG-1, MPEG-2 (DVD videos), MP3 (audio), MPEG-4, Real (audio and video), Microsoft Windows Media (video and audio), and DV video (uses JPEG and was the first, and most widely used, codec for digital camcorders). All are considered what is known as 'lossy' compression technologies since they throw away some of the information as they create the data file. This compares to 'lossless' technologies which produce a decompressed file identical to the original (an example would be PKZip).
The reason for the loss of information (compression) of video files is to achieve scalable file sizes and acceptable data delivery rates (amount of data processed/transmitted per second) when the file is viewed. DV files are too large to effectively transmit and view with current technologies without some level of compression. This level of compression is a primary variable between the different codecs and is something that we'll look at later when learning about capturing and editing files. Articles such as this one can be found on the Internet that further explain the topic of codecs and digital video compression. A little more detailed explanation of the major codecs can be found in this document which is part of the excellent resource called A & E's Technical Guides to All Things Audio and Video.
I will try to explain other new terms and concepts as they become relevant progressing through the units. A useful resource along these lines is an online glossary. Some you may want to use during the course are listed below. A Google search for something like 'digital video terms glossary' will provide you with numerous others to choose from if needed.
ShortCourses
Glossary of Digital Photography
Kramer's
Audio/Video Glossary
Kodak
Glossary of Film/Video Terms
(Images source: Animationlibrary.com)
