You say you want a revolution?
If you think digital audio players have already shaken things up, just wait for the next generation.
Nicholas Cravotta, Contributing Editor

Now, as the conductor's baton comes down to commence the second movement, what kinds of variations on the DAP theme will we hear?

Digital audio is an evolutionary innovation. The DAP is the first significant Internet appliance that isn't trying to be a mini-PC. Yet it's not an entirely new product type either. DAPs improve upon the portable CD player by allowing you to better chose the music you want to listen to, letting you carry more music with you, and giving you the DJ-like power to create your own playlists. Now, the time is approaching when DAPs take the next evolutionary step, freeing themselves from our PCs and managing content for themselves.

Current portable players compete, for the most part, on the battlefield of features—radio tuners, larger displays, equalizers, and special effects. Next-generation features will include the ability to rip (record in digital form) tracks without a PC, voice recording, and smaller form factors, such as wristwatch and neck-pendant players. DAPs are also starting to appear inside cell phones and other products, although important issues like battery life will be barriers for some time.

Ho hum

What's happened is that it isn't particularly difficult to build a DAP anymore. Companies like Cirrus Logic, Micronas, Samsung, STMicroelectronics, Texas Instruments, and Toshiba offer various chip and software products that remove most of the technical challenge.

For example, PortalPlayer has announced perhaps the most integrated digital audio chip to date, Tango. The company claims that Tango has everything a portable device needs. From an engineering perspective, Tango does come fairly complete, offering a real-time operating system, content-management software, seven digital audio decoders, several encoders, several DRM (digital rights management) tools, special effects like an equalizer and a spatializer, and support for serial or USB ports.

Based on an ARM7 microprocessor, the Tango chip runs at 140 MIPS (millions of instructions per second). To give you an idea of what 140 MIPS means, typical MP3 decoding consumes about 35 MIPS. Extras add up quickly. An equalizer takes 5 to 6 MIPS and watermarking for DRM eats up another 8 to 12 MIPS. Encoding, which allows a player to rip on its own, takes between 80 and 120 MIPS.

Significantly, more than 70 percent of PortalPlayer's 115 employees work on software. This follows a growing chip-industry trend that sees IC vendors no longer selling chips but instead hawking "platforms" or "solutions." The lesson should be obvious: Software is where vendors differentiate their products. OEMs add personalization not so much at the interface level but by adding applications such as address-book functions or voice recognition.

And product differentiation is the chief factor driving innovation. For example, when Cirrus Logic offers a chip with graphic-equalizer functions, that means every OEM using a Cirrus Logic product can offer a graphic equalizer too. Jim Long, president and CEO of Rioport, a software spin-off from Rio creator Diamond Multimedia, describes the danger. "We're in a feature war, where it's not clear anyone cares," he says. "Suddenly you end up with a product that is too hard to use. I'm not sure they add to the cause. Fancy stuff on players will take a back seat to making them easier to use. The simplicity angle here is critical."

Jim Long

Cutting the umbilical

The biggest change we're going to see with the next generation of digital audio players is their progressive movement away from the PC. Current players rely on PCs to feed them with music, either through a wired connection like USB or via media such as removable flash memory cards. And users still need a PC to procure the music in the first place, by downloading it or ripping it from CDs.

Digital audio can be so much more than just a player you can fit in your pocket. With the emergence of the Auto PC, your car will become a platform to play your favorite MP3 rips. You might run an Ethernet cable out to your garage, have a wireless connection, or drop in a flash card or a CD. In this scenario, you're still tied to a PC-based player, but it now weighs half a ton and can go 100 miles an hour.

The living-room entertainment center provides another fertile environment for sowing digital audio. A digital stereo, for example, could house a disk drive, the television could act as the display interface, and a cable set-top-box could serve as the high-speed Internet pipe.

And Bluetooth—if it ever gets here—provides the means for music to flow wirelessly among all these platforms—portable, PC, living room, and car.

Is digital audio ready to be independent? Let's take a hard look at the key technological issues involved in designing next-generation DAPs.

Start with storage. The physical side of the storage question is pretty much answered. Today's flash memories offer enough storage for more than an hour of music. And Moore's law says they'll only get denser, faster, and cheaper. Removable flash comes in a variety of formats, and the only real difficulty a DAP manufacturer faces today is finding a supplier who can provide enough flash to meet the rising demand.

However, flash isn't the only medium in the universe. Startup DataPlay recently announced a coin-sized optical disc (see "Would-be king"). And for standstill devices such as digital stereos, hard-disk drives provide an attractive cost-vs-capacity ratio (a single gigabyte can hold 16 hours of music encoded at a rate of 1-Mbyte/minute).

Location, location, location

Moreover, DAP vendors are already thinking outside of the memory box. After all, an audio file doesn't have to reside locally if you have Internet access. With a large enough pipe and streaming technology, your jukebox can encompass the whole Internet. Just look at the success of Napster, the free program that lets people make audio files on their hard drives accessible to others.

While Napster and MP3.com's "Insert your CD" idea (see "My way") may have crossed legal lines, the idea of an online repository is enticing. Take, for example, a music service provider. Instead of storing a distinct copy of a music file for each user who has legal access to it, a single copy could be stored to serve everyone.

For such visions to come true, music-manager software is crucial. Whether the player manufacturer creates a proprietary manager or teams up with an existing vendor to build a customized front-end, the manager must provide a seamless interface. The user should be able to manage the content easily and transparently. A competent content manager will have to keep track of where files are stored, what format they are in, and what legal license the user owns for them. The user shouldn't be burdened with these chores.

This model faces tall hurdles. The record companies hope to bind content to a particular PC. But that presents some serious logistical problems. For example, users will want to be able to play music across a home network. And if content can only reside on a single hard drive, what happens if that drive fails or if you upgrade your computer? How do rights transfer? In the old days, when a couple split up, he took his records and she took hers. But how do you divide up digital files?

Declaration of independence

The hardest problem to solve for next-gen players is independent Internet connectivity—freeing players from the mandatory PC link. Several companies are looking for their players to go straight to the Web through an internal modem. We may see a few this year, but design cycles, and cost, will probably push such introductions into next year.

In the PC space, the most cost-effective modem is a "soft" modem. Instead of paying for modem hardware, which only gets used part of the time, PC makers take advantage of the powerful PC processor to run a software-based modem. A Pentium-grade processor can run a V.90 modem without much degradation of overall performance.

Embedded devices like DAPs have no Pentium on which to piggyback. However, a powerful enough DSP (digital signal processor) could act as both a modem and a digital audio decoder. Except in streaming applications, the DSP could act as either a modem or decoder, but not both at once. Utilizing the same silicon this way keeps cost down.

Several companies, such as Hitachi, are actively targeting the embedded Internet space. Hitachi's SH3-DSP combines the functions of a regular processor and a DSP, giving it an edge in this kind of application. Such chips still carry price tags too high for DAPs, but the technology is in place for the convergence to occur.

But a player with an internal modem still faces the problem of having a slow connection to the Internet. Sure, you could dial into your favorite MP3 site from a pay phone, but you'd find yourself standing there for a very long time. For independent DAPs to survive, they'll need broadband connectivity.

Broadband technologies such as DSL and cable modems are now seeing widespread deployment. However, DSL chipsets cost too much to consider adding one to a DAP, and software-based DSL is pie-in-the-sky even for PCs. In any case, where would you find a DSL line for your player in the first place? If you do happen to come across an accessible line, there's probably a computer with a USB port there anyway.

Perhaps what makes the most sense for an independent portable player is a shared broadband connection to the Internet, through either Ethernet, USB, or a wireless link. With home gateways on their way, a portable player could plug right into a home network to access the Internet via the gateway's DSL or cable connection.

Don't get awkward

Which brings us back to what makes a DAP independent of a PC. From one perspective, adding a modem will free a player from the hold of a PC today. On the other hand, many players already have USB, which is enough to hook them into a home gateway and DSL. Technically, these DAPs are already potentially free of the PC, but only if you can actually locate a gateway to plug into.

Once the PC is out of the picture, DAPs will need access to large amounts of storage to manage digital rights and archive digital files. This could be an Internet-accessible drive or even a personal PC acting as a server.

However, small size and simplicity rank as the portable player's most appealing features; throw a screen on the player so a person can surf the Web for files and the player becomes unwieldy, expensive, and difficult to use.

DAPs will need to be able to surf themselves, with only limited human guidance. For example, when you press the player's Internet button, the DAP could hook into a dedicated site for DAPs only. But some interface will be necessary. What will users tolerate? A bulky screen and a bunch of buttons? Voice recognition?

Perhaps the biggest stumbling block for digital audio today is copyright protection and the digital-rights management (DRM) schemes that are popping up to provide it. "Protective measures," in this issue, discusses DRM schemes in detail. Here, we'll limit ourselves to how the current DRM situation impacts player evolution.

New DRM concepts are appearing with great regularity, and the industry has yet to show any sign of slowing this pace down, never mind coalescing around a single standard. Yet DRM has to work right out of the gate. People won't tolerate paying for a song and then not being able to play it because their player doesn't support that standard.

For example, a track might come with a 30-day trial period before you have to pay for it. "But what happens on the 31st day when it stops playing?" asks Michael Maia, marketing VP at PortalPlayer. Will consumers be angry and confused when they pick up their player to go out for a run or a long trip and find that songs have expired? "We're still not sure what the psychological aspects of that will be," Maia says.

So player vendors have to be flexible when supporting DRM. Imagine the backlash from angry users if the adoption of a new standard made their $300 players obsolete overnight. The SDMI (Secure Digital Music Initiative), a group trying to lead digital content protection forward, only offers defining guidelines, leaving significant room for interpretation and implementation. Therefore players must accept firmware upgrades so they can support multiple DRM formats, as well as new audio formats, as they appear.

Supporting multiple formats should have little impact on processing performance (unless the DRM employs complex keys for streaming decryption) or memory (the player can steal a little flash space for the DRM code, reducing maximum play time by a few seconds at worst).

Of course, as soon as you open a system to firmware upgrades, you open the system to spoofing. The SDMI mandates that security should keep honest listeners honest. Quite frankly, that may not be a strong enough principle. You can break into a system for two reasons—for yourself or for everyone. Cracking a single key provides access to a single track or a single player. But cracking a player's firmware and, say, inserting a new version that ignores all rights checks, has the potential to break copy protection for every similar player. Suddenly a lot of honest people may be very tempted. If such firmware cracks can be created, it's safe to assume that they will be; the digital audio culture has already demonstrated that it includes hackers with plenty of time on their hands.

This places a burden on player manufacturers to not only protect content but also to protect the players themselves from casual break-in. Players will require encryption protection; the firmware should be stored safely in encrypted form, only to be decrypted inside the player.

A flexible design is important not only to future-proof a player against evolving DRM and audio standards, but also to provide malleability in the user interface. As DAPs become independent of a PC, they must be flexible enough to support new kinds of services. For example, a DAP released today should be able to interface with the vendor's future DAP-only web site. Additionally, different users will favor different features and options. A programmable or customizable interface could open the door to new markets.

Having to support multiple formats and accommodate formats that aren't yet in existence doesn't exactly make design easier. "There's a lot of chaos in the market," says PortalPlayer's Maia. Chaos, of course, equals opportunity.

Author information

Contributing Editor Nicholas Cravotta wrote about voice-over-data technologies in our April issue.