Why FireWire is better for video editing

IEEE 1394 to USB Comparison

Gentlemen, prepare to duke it out. In this corner, we have USB (Universal Serial Bus) 2.0, beloved by the Wintel community. In the other corner is FireWire, developed and promoted by Apple. Who will win?

This, of course, is an oversimplification of the intense debate that's underway. But Intel does have a vested interest in the PC controlling peripherals, the debate will only get more intense in the days ahead. The target speed for USB 2.0 is 480 Megabits per second (Mbps), or 40 times faster than USB 1.1. Meanwhile, FireWire already operates at 400 Mbps and is expected to reach 800 Mbps and 1600 Mbps later this year.

Although Apple has brought USB to the general public and popularized the technology with the iMac, the standard's inventor is trying to change USB into a high-speed implementation that can compete with Apple's now booming FireWire connectivity. As part of his keynote address at this year's (2000) Intel Developer Conference, Pat Gelsinger, Intel Desktop Products Group vice president and general manager featured a USB 2.0 system demonstration with a USB 2.0-ready PC and scanner. (See Ben Wilson's article for details.) "Intel Developer Forum is known for identifying industry trends and the technologies that will make them happen, so we are delighted to be one of the first to demonstrate the capability of USB 2.0 using NetChip's device technology in the scanner," Gelsinger said. "This demonstrates that USB 2.0 is real, and goes a long way toward building momentum for this technology."

Not surprisingly, Apple hasn't yet commented on its plans, or lack of them, for USB 2.0. But to put the matter in perspective, let's look at the big picture.

USB: whassup?

USB is a cross-platform industry standard for connecting peripherals to computers, and offers a 12-megabit per second data transfer rate, which is pretty darn fast, though not earth-shattering. USB provides the ability to connect up to 127 devices to a single computer (though we've never heard of anyone actually doing this). Although USB was developed for the Wintel world, Apple has become one of its major proponents.

What's so nifty about USB?

Several things. First, it's "hot swappable," eliminating the need to reboot or restart your Mac when attaching a device. You attach peripherals through interconnected external hubs. When your Mac's ports fill up, just attach a "hub" that provides additional ports (usually four or seven), and keep on plugging in more peripherals and hubs as needed.

With USB, there's no need for terminators, memory addresses or ID numbers with USB devices. There's only one kind of cable (USB A-B), which has different connectors at each end, so you can't connect an USB device incorrectly. Various sorts of devices can plug into a USB port: digital cameras, printers, Zip drives, SuperDisk drives, floppy drives, mice, keyboards and lots of other peripherals.

Which brings us to USB 2.0. In February of 1999, Intel announced that they were creating a consortium of companies to bring USB to faster speeds, and allow it to compete with IEEE-1394 FireWire. This USB 2.0 spec, is supposed to allow USB to utilize the full range of devices including cameras, drives and other things that USB was never intended to work with. This is quite a shift from the original goal of USB, which was to provide connectivity for low to medium speed devices. Intel and its USB 2.0 consortium buddies plan to ramp up USB speeds 40 fold or more, going from 12 Mbps to 480 Mbps.

Despite the fact that there are still technical hurdles to leap, USB 2.0 won't be supported by motherboard chipsets -- in other words, appearing on a computer near you -- for probably another year, at least. Then it will be longer still until peripheral manufacturers jump aboard.

FireWire: whaszat?

FireWire is a high-performance connection standard for personal computers and consumer electronics that makes USB look sluggish. FireWire can move large amounts of data between computers and peripheral devices at transfer rates of 100, 200 and 400 Mbps (12.5, 25 and 50 megabytes per second, respectively). In simpler terms, it's a heck of a lot faster than USB.

At such speeds, you could, for instance, plug in a digital camcorder and transfer video data into your Mac as a pure digital signal without going through the usual digital-to-analog and analog-to-digital conversion process. FireWire also supports device-to-device transfers for which you'd not even need your computer. Want to transfer digital video data from your digital camera or camcorder to a digital VCR? No problem -- if the manufacturers of such devices build them to take advantages of FireWire's capabilities.

Like USB, FireWire is hot pluggable; up to 63 devices (using cable lengths up to 14 feet) can be attached to a single bus and connected and disconnected as needed. FireWire cables are easy to connect because there's no need for device IDs, jumpers, DIP switches, screws, latches, or terminators.

FireWire speeds up the movement of multimedia data and large files and enables the connection of digital consumer products -- including digital camcorders, digital videotapes, digital videodisks, set-top boxes and music systems -- directly to your computer. The technology allows for video capture directly from both new DV camcorders with built-in FireWire ports, and from older analog-only equipment using A/V to FireWire converters.

FireWire was developed with streaming digital media in mind. The technology allows for isynchronous transport, meaning that any two devices on the bus can have guaranteed bandwidth through which to pass data.

Besides the aforementioned products, you can also get FireWire-savvy scanners, storage devices, printer interface cards, A/V converters, digital audio mixers and printers. Of course, you may not have the time, desire, or, most importantly, money to indulge in such extravagances, but, hey, it's possible.

FireWire versus USB

While FireWire sounds like USB on steroids, the technologies serve different purposes. FireWire -- a much cleaner and more advanced spec than USB -- is for peripherals that need maximum bandwidth. USB is a medium bandwidth connection for peripherals such as digital still cameras, monitors, keyboards and mice.

But with USB 2.0 looming on the horizon, will FireWire wilt and fade? Possibly, but not likely. The prediction (that is, the prognosis of Yours Truly) is that, even if version 2.0 does what's being promised -- and that's probably not going to happen anytime soon -- it and FireWire will coexist peacefully. It seems doubtful that USB 2.0 will encroach too much on digital video and audio territory that FireWire has slowly but surely conquered.

Why? FireWire can transfer data point-to-point (one device to another) while USB requires the computer to server as a go-between. In other words, moving data with USB means you have to move it from one doohickey to your computer, then transfer it from the computer to the other doohickey. FireWire can move data directly from one device to another. Plus, as we mentioned, FireWire will soon hit speeds of 800 Mbps, late this year or early in 2001. And there's speculation of speeds of up to 1.6 Gbps a year or two down the road. So expect USB and FireWire to live together, if not in harmony, at least in some sort of truce.

Topology

The topology of 1394, known as a tree topology, is shown in figure 1 below. Any device can be connected to any other device, so long as there are no loops. A 1394 network can support up to 63 devices. The devices can be hot swapped. If a device is added or removed, the bus will reset, reconfigure, and continue operation. If the bus is broken, the two pieces will reset, reconfigure, and resume operation as two independent busses. 1394 also offers peer-to-peer connectivity, so peripherals can talk to one another without intervention from the PC. Fig 1 (1394_TOPOLOGY.GIF) In contrast, USB has what is known as a star-tiered topology shown in figure 2 below. The PC acts as the host. Each device is connected to a hub, which provides sockets and power and acts as a repeater. Hubs can be either self-powered or bus powered. They can also be cascaded. The USB topology supports up to 127 devices.

Speed

USB offers speeds ranging from 1 Mbits per second to 12 Mbits per second. In contrast, the current IEEE specification 1394-1995 offers speeds starting at 100 Mbits per second and going up to 400 Mbits per second. P1394b will start at 800 Mbits per second and is defining speeds of up to 3200 Mbits per second. P1394b is expected to be fully backward compatible with the 100-400 Mbits per second specification, - connector cable and software.

Application

As mentioned previously, 1394 and USB are complimentary technologies. USB is a medium bandwidth connection for telephony products, digital still cameras, monitors, keyboards, mice, and other similar I/O devices. In contrast, 1394 is a high-speed bus designed for digital video cameras, DVD players, mass storage devices, and other peripherals that require greater bandwidth.

Cost

USB is a very low-cost interconnect technology. Low-speed USB implementations for devices such as mice and keyboards typically cost less than $1 in OEM quantities, and even the medium-speed implementations for devices like scanners and modems are in the $1-2 range in OEM quantities. Due to relatively lower volumes and higher complexity, 1394 implementations are currently in the $15 range. This cost is expected to decrease as volume builds over the next few years.

Meeting the Needs of Tomorrow's PC

Figure 3 below summarizes the differences between USB and 1394. Tomorrow's PC will have a need for low-cost, low-bandwidth devices like mice, keyboards, and modems. USB provides a good fit for these devices. Tomorrow's PC will also need a high-speed interface for connecting to high-speed printers, hard drives, and camcorders. 1394 is the technology that will allow these devices to interoperate with the PC. Both USB and 1394 will coexist on future PC platforms to meet a wide range of growing peripheral interconnectivity needs.

Opportunities for OEMs, IHVs and ISVs

You can find both USB and 1394 peripherals in stores today. USB keyboards, mice, and tethered cameras are all available today. There is a significant opportunity for USB peripherals since most PC's are shipping with USB ports today.

The main 1394 peripheral today is the digital, or DV, camcorder. DV camcorders can be found on store shelves today, but are still quite pricey. In 1998, look for 1394 add-in cards on high-performance PCs geared for digital video editing. There is currently a need for 1394 software products for digital video editing and other digital imaging applications, especially products that will work under Windows* 98. In the near future 1394 hard disk drives and DVD drives will begin to appear as well.

Beyond this year (2000), you can expect to see a higher level of integration with 1394 on the PC platform. As the installed base of 1394-enabled PCs grows, there will be considerable opportunity for 1394 peripherals such as printers and scanners. Intel is currently designing with P1394a rather than IEEE Standard 1394-1995 due to P1394a's significant performance, compatibility and interoperability benefits. P1394a is near its final state and should be submitted to the IEEE balloting process in 2001.

OEMs and IHVs should look today for opportunities to design in support for both USB and 1394 as they will coexist together on the PC platform for the foreseeable future.

 

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