Movies on the Move

A video library in your pocket and camcorders with no moving parts: the MPEG-4 wave is coming your way

5 min read

The MP3 audio-compression format is a technical standard-turned-fashion fad: MP3 players have become ubiquitous on city streets in many parts of the world. It's probably no surprise that, as television followed radio, the next standard-turned-fad will likely be a video-compression format: MPEG-4.

MPEG-4 became an internationally recognized standard in 2000. The visual equivalent to MP3, it was developed by the same organization, the Moving Picture Experts Group, an international working group operating under the auspices of the International Organization for Standardization and the International Electrotechnical Commission. Like MP3, MPEG-4 offers very compact file compression at selectable data rates. This allows users to make a tradeoff between quality and required storage space.

MPEG-4 represents a big advance over earlier image compression standards. At its highest quality and bit-rate levels, MPEG-4 can produce images superior to those produced with MPEG-2 (the DVD recording format), with only one-third to three-eighths the data.

With the new availability of high-quality digital video in manageable file sizes, pocket video players and camcorders with no moving parts are starting to appear, as well as hard drive-based video jukeboxes holding dozens of full-length movies. Soon, people will carry their movies, along with their music, in their shirt pockets.

Some of these new players and camcorders store video files in flash memory, such as the Secure Digital (SD) memory cards used in digital cameras and PDAs. Solid-state media make for a very compact and rugged player or camcorder--but this comes at a price: only minutes, rather than hours, of video can be stored.

Photo: RCA

The Fisher FVD-CI Pocket CameraCorder is one of the lightest cameras around, weighing in at only 170 grams.

More recently, a pair of players--one from Archos Technology, Irvine, Calif., and the other from RCA, a unit of Thomson SA, Boulogne, France--has gotten around the memory problem by building their devices around standard 2.5-inch (63.5-mm) laptop hard-disk drives with capacities up to 80 gigabytes. Both the players are powered by rechargeable lithium-ion batteries, and both let you play movies on your TV--with picture quality similar to that of VHS--as well as on the built-in LCD.

Of the two, the winner is the Archos, for its more complete and usable software. Archos, a leader in the hard-drive-based MP3 player category, has introduced a gorgeous line of combination MP3/MPEG-4 multimedia jukebox players that feature a 9.65-cm LCD screen. The three models vary in storage capacity from 20 GB up to 80 GB. These units can also store photos and act as backup devices for your computer. You can add an optional camera module for US $199 that takes stills and full-motion video, saving them straight to the hard drive.

The RCA Lyra RD-2780, with its 8.89-cm LCD, is similar to the Archos devices at a slightly lower price. It doesn't offer a camera module, though, and the operating software is missing many features: try to adjust the contrast of the screen, for example, and a box pops up telling you to check the RCA Web site for a software update. Actually updating the software didn't result in the hoped-for functionality: it simply deleted the contrast control altogether! Releasing a product with such incomplete software is simply unacceptable.

Because few people have libraries of MPEG-4 content ready to load, the Archos and the RCA players can record analog video from sources such as your VCR or camcorder. Using an included snap-on recording module, the Archos AV series converts the video into ready-to-view files. The RCA doesn't require a snap-on attachment to record, but unlike the Archos, it accepts only normal composite video input, not S-video. Composite video is available from all VCRs but is of lower quality than S-video. For viewing on the tiny screen, the difference probably won't be noticeable, but it might be evident on larger screens.

Photo: RCA

Resolution of the Mustek DV 4000 camcorder is only 352 by 288, but for less than $200 it makes a fun toy.

Why don't these machines have TV tuners and timers, so that they can be used like miniature TVs with built-in TiVos? That would be the ultimate pocket video machine! The obstacle, according to Marco Delrosario of Archos, is legal, not technical. Because of the reproducibility of digital recordings, copyright concerns keep this handy functionality out of your pocket. Considering that the Archos machines can record the analog output from a DVD player--despite the presence of anticopying signals--it's puzzling that there's such worry about capturing unprotected signals off the public airwaves. However, units that can do just that are rumored to be coming soon from other manufucturers.

Things aren't quite so rosy on the camcorder side: the current generation of no-moving-parts camcorders offers recording times that are almost comically short--as little as 11 minutes. Also, memory cards are much more expensive than tape; the combination of short recording time and the high cost of additional cards demands frequent transfer of material to a computer. Another big problem is that creating MPEG files requires a lot more processing power than simply playing them back--in fact, at MPEG-4's highest possible quality, a little more power than can be easily squeezed into a camcorder. The problem is eased at reduced resolutions, but this can result in state-of-the-art camcorders capturing video at a quality that would be mediocre for a VHS tape. All this means that MPEG-4 isn't up to the standards of today's best tape-based machines.

Nevertheless, the opening salvos have been fired, and it's only a matter of time before moving parts in video cameras go the way of the phonograph needle.

Photo: RCA

Pocket video players like the Archos AV 380 still lack the ability to receive television signals.

Currently leading the way at the high end is the Panasonic SV-AV series made by Matsushita Electric Industrial Co., Kadoma City, Japan. In its highest-quality MPEG-4 mode, the top-of-the-line Panasonic SV-AV100 can store more than an hour of video. But the resolution is so low (320 by 240) that the picture isn't quite on a par with VHS quality. Given that competing products using digital MiniDV tapes offer resolutions up to 720 by 480, pixelated, sub-VHS images just won't fly.

To accommodate the limitations of current MPEG-4 hardware, the SV-AV100 also offers the option of recording video in the older MPEG-2 format: the quality is impressive, but the files are much larger. Its highest-quality MPEG-2 mode will exhaust the included 512-megabyte SD card in 11 minutes--not a lot compared with the two-hour maximum available from MiniDV tapes. The suggested retail price is high, too: $999.95.

The new Fisher FVD-C1 Pocket CameraCorder, from Sanyo-Fisher Corp., Chatsworth, Calif., offers better resolution. Available for $899, at only 170 grams the combination camera/camcorder is one of the lightest devices around and measures just 10.9 by 6.9 by 3.3 cm. It offers up to 21 minutes of 640 by 480 video on a 512-MB SD card, using a data rate of 2 Mb/s. It can store 3.2-megapixel stills and has a built-in flash. It's also one of the few SD card products to explicitly offer Macintosh as well as Windows compatibility.

On the lower end of the price scale are the Mustek DV 3500, DV 4000, and DV 5000 memory-card camcorders. They provide a rather low resolution of 352 by 288 when recording at 30 frames per second, but they also cost very little--starting at less than $200--and should be fun toys for very casual video recording or Web use.

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The Inner Beauty of Basic Electronics

Open Circuits showcases the surprising complexity of passive components

5 min read
A photo of a high-stability film resistor with the letters "MIS" in yellow.
All photos by Eric Schlaepfer & Windell H. Oskay

Eric Schlaepfer was trying to fix a broken piece of test equipment when he came across the cause of the problem—a troubled tantalum capacitor. The component had somehow shorted out, and he wanted to know why. So he polished it down for a look inside. He never found the source of the short, but he and his collaborator, Windell H. Oskay, discovered something even better: a breathtaking hidden world inside electronics. What followed were hours and hours of polishing, cleaning, and photography that resulted in Open Circuits: The Inner Beauty of Electronic Components (No Starch Press, 2022), an excerpt of which follows. As the authors write, everything about these components is deliberately designed to meet specific technical needs, but that design leads to “accidental beauty: the emergent aesthetics of things you were never expected to see.”

From a book that spans the wide world of electronics, what we at IEEE Spectrum found surprisingly compelling were the insides of things we don’t spend much time thinking about, passive components. Transistors, LEDs, and other semiconductors may be where the action is, but the simple physics of resistors, capacitors, and inductors have their own sort of splendor.

High-Stability Film Resistor

A photo of a high-stability film resistor with the letters "MIS" in yellow.

All photos by Eric Schlaepfer & Windell H. Oskay

This high-stability film resistor, about 4 millimeters in diameter, is made in much the same way as its inexpensive carbon-film cousin, but with exacting precision. A ceramic rod is coated with a fine layer of resistive film (thin metal, metal oxide, or carbon) and then a perfectly uniform helical groove is machined into the film.

Instead of coating the resistor with an epoxy, it’s hermetically sealed in a lustrous little glass envelope. This makes the resistor more robust, ideal for specialized cases such as precision reference instrumentation, where long-term stability of the resistor is critical. The glass envelope provides better isolation against moisture and other environmental changes than standard coatings like epoxy.

15-Turn Trimmer Potentiometer

A photo of a blue chip
A photo of a blue chip on a circuit board.

It takes 15 rotations of an adjustment screw to move a 15-turn trimmer potentiometer from one end of its resistive range to the other. Circuits that need to be adjusted with fine resolution control use this type of trimmer pot instead of the single-turn variety.

The resistive element in this trimmer is a strip of cermet—a composite of ceramic and metal—silk-screened on a white ceramic substrate. Screen-printed metal links each end of the strip to the connecting wires. It’s a flattened, linear version of the horseshoe-shaped resistive element in single-turn trimmers.

Turning the adjustment screw moves a plastic slider along a track. The wiper is a spring finger, a spring-loaded metal contact, attached to the slider. It makes contact between a metal strip and the selected point on the strip of resistive film.

Ceramic Disc Capacitor

A cutaway of a Ceramic Disc Capacitor
A photo of a Ceramic Disc Capacitor

Capacitors are fundamental electronic components that store energy in the form of static electricity. They’re used in countless ways, including for bulk energy storage, to smooth out electronic signals, and as computer memory cells. The simplest capacitor consists of two parallel metal plates with a gap between them, but capacitors can take many forms so long as there are two conductive surfaces, called electrodes, separated by an insulator.

A ceramic disc capacitor is a low-cost capacitor that is frequently found in appliances and toys. Its insulator is a ceramic disc, and its two parallel plates are extremely thin metal coatings that are evaporated or sputtered onto the disc’s outer surfaces. Connecting wires are attached using solder, and the whole assembly is dipped into a porous coating material that dries hard and protects the capacitor from damage.

Film Capacitor

An image of a cut away of a capacitor
A photo of a green capacitor.

Film capacitors are frequently found in high-quality audio equipment, such as headphone amplifiers, record players, graphic equalizers, and radio tuners. Their key feature is that the dielectric material is a plastic film, such as polyester or polypropylene.

The metal electrodes of this film capacitor are vacuum-deposited on the surfaces of long strips of plastic film. After the leads are attached, the films are rolled up and dipped into an epoxy that binds the assembly together. Then the completed assembly is dipped in a tough outer coating and marked with its value.

Other types of film capacitors are made by stacking flat layers of metallized plastic film, rather than rolling up layers of film.

Dipped Tantalum Capacitor

A photo of a cutaway of a Dipped Tantalum Capacitor

At the core of this capacitor is a porous pellet of tantalum metal. The pellet is made from tantalum powder and sintered, or compressed at a high temperature, into a dense, spongelike solid.

Just like a kitchen sponge, the resulting pellet has a high surface area per unit volume. The pellet is then anodized, creating an insulating oxide layer with an equally high surface area. This process packs a lot of capacitance into a compact device, using spongelike geometry rather than the stacked or rolled layers that most other capacitors use.

The device’s positive terminal, or anode, is connected directly to the tantalum metal. The negative terminal, or cathode, is formed by a thin layer of conductive manganese dioxide coating the pellet.

Axial Inductor

An image of a cutaway of a Axial Inductor
A photo of a collection of cut wires

Inductors are fundamental electronic components that store energy in the form of a magnetic field. They’re used, for example, in some types of power supplies to convert between voltages by alternately storing and releasing energy. This energy-efficient design helps maximize the battery life of cellphones and other portable electronics.

Inductors typically consist of a coil of insulated wire wrapped around a core of magnetic material like iron or ferrite, a ceramic filled with iron oxide. Current flowing around the core produces a magnetic field that acts as a sort of flywheel for current, smoothing out changes in the current as it flows through the inductor.

This axial inductor has a number of turns of varnished copper wire wrapped around a ferrite form and soldered to copper leads on its two ends. It has several layers of protection: a clear varnish over the windings, a light-green coating around the solder joints, and a striking green outer coating to protect the whole component and provide a surface for the colorful stripes that indicate its inductance value.

Power Supply Transformer

A photo of a collection of cut wires
A photo of a yellow element on a circuit board.

This transformer has multiple sets of windings and is used in a power supply to create multiple output AC voltages from a single AC input such as a wall outlet.

The small wires nearer the center are “high impedance” turns of magnet wire. These windings carry a higher voltage but a lower current. They’re protected by several layers of tape, a copper-foil electrostatic shield, and more tape.

The outer “low impedance” windings are made with thicker insulated wire and fewer turns. They handle a lower voltage but a higher current.

All of the windings are wrapped around a black plastic bobbin. Two pieces of ferrite ceramic are bonded together to form the magnetic core at the heart of the transformer.

This article appears in the February 2023 print issue.