8mm Movie Film, Super 8 Film, and 16mm Movie Film
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Tutorial

Digital Media

By: Bruce Mayfield

Media, in the scope of the digital world, is an object or device, such as a disk or tape, on which data is stored. Over the years there has been a great many different forms of digital storage, some very successful, some utter failures.

Classes of media.

There are two common media types - magnetic and optical. These types come in two primary forms - platter and tape.

Optical media uses light, often in the form of a laser beam, in some way to represent those 1s and 0s (bits).

Magnetic media uses tiny clusters of ferrous metals to hold a magnetic charge. The "sort or strength" of each magnetic charge represents a 1 or a 0 (a bit of information) -- the most basic part of digital information. Magnetic tape and hard drives technology are examples of magnetic media.

Metallic Tape media is functionally a 3 dimensional storage medium. Not only is data stored on it's length and breath, but by winding yards of tape onto itself (the 3rd dimension), onto a spool, tape is a highly compact and cost effective media. Finally, data stability of tape is not vulnerable to physical impacts -- like bumping or dropping the tape. It is this last characteristic that qualifies digital tape as an archive and disqualifies a hard drive as an archive.

(See a comparison of analog and digital tape meda)

Platter media is equally common in magnetic and optical types. Its advantages are speed and random accessibility. Just one move the read head -- to the right track -- and then wait for the data to come to the read head. It's weakness is in size compared to capacity - though this is slowly changing as new and more compact storage technologies are developed.

Hard Drives as archive media are very vulnerable because almost anything can cause them to crash -- power surges, static discharge, bumps, thumps, wear on the bearings and head motors. God forbid you drop a removable drive -- even one inch -- with ALL your movie film archives on it. New "high impact" hard drive" claim -- but will not guarantee -- safety of data from a height of 3 feet -- more or less.

Specific types of media.

Hard drives are a magnetic platter media that you're probably somewhat familiar with. Home computers have used hard drives as their main method of storing information since the late 1980s. Very fast and flexible, a hard drive can't be beat for on-line, immediate access storage.

They are delicate, however. Dropping one from as little as one foot above a hard surface can kill them, losing every last bit of information they contained. This is why the computing industry is forever repeating their computer use mantra: Back-up, back-up, back-up.

CDs and DVDs are the most well known forms of optical platter media. They're significantly slower than hard drives and hold far less information, but are a very great deal tougher. So much so they can be used with nothing protecting them - the disk can be handled directly.

A CD-R and a DVD-R

The computer industry has been using them for distributing information for a long time as a superior media for delivery of software and data than the magnetic platter we all know as a "floppy disk". In fact, with the advent of recordable CDs and recordable DVDs, the floppy disk is now disappearing.

DVDs were a natural for video, a tough media with sufficient capacity to hold some high-quality though rather compressed video. As the picture quality was far superior to VHS in image quality and it was far tougher than VHS as a medium it appealed to the consumer and movie rental industry. (See the difference between commercial DVDs and DVD+/-Rs.)

CDs can actually be used to hold video - called VCD if used in this way. Because they only hold about 700 megabytes of information, the 70 or so minutes of video they hold is deeply compressed and is only slightly better than VHS video.

MiniDV tapes Panasonic "MQ"

MiniDV is a very common magnetic tape technology. It was born from the introduction of the DV (digital video) format, made compact for portability and use in camcorders. Because of its quality as compared to its low cost, MiniDV became very popular in the consumer, semi-professional and "no-budget cinema".

For it's small size it can hold an astonishing amount of information - almost 14 gigabytes.

Digital 8 (D8) is a hybrid of the DV format and the Video8 (and Hi8) analog tape form factor. It is very similar to MiniDV save for the tape form factor.

DigiBeta (Digital Betacam) is the latest iteration of the professional Betacam format - similar to DV in that it's using an older analog tape media (Betamax) to store digital information, it can store a far greater amount of information, and therefore the video stream stored on it is less compressed. Considered top-quality for broadcast, the expense of the equipment keeps this technology in the studios of broadcasters and the occasional video enthusiast.

An overview of other video media.

Video has been stored in analog form for much longer than it's been stored digitally. Let's look at some of the most popular mainstream media:

VHS (Video Home System) was introduced in late 1976 and was far and away the most popular video media before DVD took over that role. It launched the movie rental industry, made it easy to watch the television programs we wanted to without having to juggle schedules, and was a good way to capture our own home movies. Unfortunately VHS was low quality, with poor color sampling, low resolution and had a certain delicacy to the signal.

Betamax was a contender for the position VHS had occupied, in fact having started the home VCR market in 1975. You will find many people who say the Beta format was in fact superior to VHS with better color sampling and higher resolution - approaching broadcast quality. However a price war between the makers of Beta and the makers of VHS as well as a lawsuit over copyrights as related to people recording TV shows and movies eventually pushed Beta out of the market it had created.

LaserDisk is an unusual non-digital optical platter media. Called "DiscoVision" when it was first brought to market in 1978, later market forces changing the name of the format to "LaserDisk". It's much like a CD save for two things: The pits and smooth areas store analog information, and it's much larger.

Video8 is an 8mm analog tape format introduced by Sony in 1985. It had advantages over VHS tapes of the time - notably in size - that made it popular for the home video camera market. Later improvements to the technology brought Hi8 into existence, and it now has a digital format called Digital8 similar to MiniDV in that it uses the industry standard DV format.

Now that you're familiar with the various media video is stored on, and familiar with some of the terminology used in the field, we can have a look at archiving concepts.