The Fossilized Remains of The Age-Old DVD Player
An In-Depth Look at How Movies Actually Appear on Your TV Screen
A standard, one-layer DVD can store up to 4.7 Gigabytes (GB) of digital data, comparable to about two hours of audio and video. It is often underestimated, in comparison to today’s technological arsenal, just how essential DVD’s once were in delivering information from one place to another.
Your typical household likely displayed shelves upon shelves of DVDs. The prominence of them in certain households might make one think that it stands as a symbol of wealth or high status, almost as if how large your Star Wars Saga DVD collection, or your gathering of horror movies, makes you better than the next family. They had an unprecedented “collector culture”, as Andy Patrizio — a veteran freelance journalist — calls it in a Computerworld article comparing DVD and VHS. Nonetheless, the bulkiness of DVD’s and the DVD Player have given engineers the fuel to strive for the sleeker, smoother technology present in the digital world today.
Before the magic of today’s digital world can be explained, it is important to look back not so long ago, to the early 2000’s, when popularity of the DVD was at its peak.
The wonder experienced as a kid, seeing my Finding Nemo DVD slide into the button-filled box after popping the tray out, remains unmatched. No one in my family could explain how the small, 12 cm disc transformed into a wide array of colors and sounds on our TV screen. To be honest, it wasn’t something I really cared to find out more about, either. Now, though, I have become determined to decipher exactly what witchcraft was employed in order to allow Nemo and Dory to swim around and explore the depths of the ocean.
The similarities between a DVD and a CD player are very striking. A row of laser beams shine onto the face of the disc in order to read its unique pattern of ridges. In simple terms, each bump on the DVD contains an encoded mix of audio and video, that is amplified onto the TV. The most common format of this decoding is called MPEG-2, which is the standard composite video signal used by DVD players.
Considering how small the bumps must be in order to project such lengthy footage, precision is the most important aspect of well-made DVD players. Each one is comprised of three main elements: A drive motor, a laser and lens system, and a tracking mechanism.
The drive motor is responsible for spinning the disc so that the movie is able to play at normal speed. The speed and direction of the motor dictate what track is being played and gives DVD players the ability to fast-forward or rewind on command. It rotates at speeds from about 200–500 rpm (revolutions per minute).
The laser and lens system is used “to focus in on the bumps and read them.” A DVD has several layers that the laser must analyze. The main layer is actually under a microscopic outer coating of semi-transparent reflective material. It goes through this main layer and hits the reflective layer behind it. It reflects onto an “opto-electric” device, a piece of technology in the player that channels different light waves. Specific light waves correspond to bits, and these make up the bytes of data in the movie or film. Bytes refer to a larger unit of memory compared to bits. Eight bits make up one byte.
It should be noted that a single nanometer is one million times smaller than a millimeter. Compared to a CD Player, the wavelength of the DVD lasers light is about 140 nanometers smaller. This gives DVD players their unique ability to adapt to the particularly tiny pits in the discs.
The third component is the tracking mechanism. Its job is to move the assembly of lasers in such a precise way so that the beam can keep up with the spiral track. The tracking system has to continually move the laser outward. The bumps spin by the lasers faster as the laser moves towards the edge of the disc. Accordingly, the speed of the drive motor slows down to ensure the bumps revolve around the lasers at a constant rate.
Another crucial component to just about any piece of technology is a circuit board. This is basically the power supply located just inside the “shell” of any electronic. Modern technological capabilities have allowed DVD players to function with only one circuit board within it. They consist of capacitors, resistors, transistors, coils, and switches; all parts that are “used to… electrically connect electronic components using conductive pathways”.
Now that the DVD is able to read the discs data, how exactly does it end up on a screen? There are several additional parts, coming in the form of software or wires that connect between the DVD Player and screen that its being broadcasted on.
A Dolby Digital decoder is a feature present in all modern DVD players. It deciphers some of the digital data on the DVD and transports it through six different audio channels.
The most modern product for projecting video is Component Video output. There are three separate connectors for this type, that plug into the DVD player from your TV or computer. The factor that differentiates this type of video from older models is that the separate cables are only used to project certain colors, making them appear more vibrant on the screen. It uses a color space — an organization of colors — known as Y-PB-PR. Each part: Y, B, and R represent different colors on the spectrum.
The Y-cord carries “Luma”, which depicts the brightness of an image.
The PB-cord carries color from Blue to Yellow.
The PR-cord transcribes colors ranging from Yellow to Red.
Assigning each cord to only half the colors results in a better picture quality overall.
The significance of DVD players may now be dulled by 2020’s plethora of technology. However, just like a person seeking information about their ancestry, it is still important to look back as uninformed consumers, at how things have changed. It isn’t until we look back on mechanization from a few years ago, that we can truly grasp how far we’ve come as humans since.
We now have streaming access to thousands of movies and shows with merely the push of a button — or a few — and DVD’s have become an ancient artifact, replaced by invisible bytes of downloadable data on the internet.