USB 2.0 and Video

by Andrew Alexander
Published on Sep 11, 2001 12:00 AM



Most computers built after 1996 will have as standard equipment, a USB port ("Universal Serial Bus"). The port is used to connect devices such as printers, scanners, mice, keyboards, digital cameras and other "simple" devices to a computer. The standard was developed in 1992, by a group of technology designers - including Intel, IBM, Microsoft, and others - to allow computer users to connect peripherals without having to turn off the power and reconfigure the system.

Until recently, the USB standard has been completely unsuitable for use in digital video; its available bandwidth (the amount of data it can send across a cable in a given time) is lower than required for digital video. However, USB was not originally designed to compete with FireWire; it served a different market in connecting low-power peripherals to the computer. You wouldn't connect a keyboard to a computer with a FireWire connection - it would be too expensive, and you would never use that much bandwidth with a keyboard.

For whatever reason, the USB consortium has introduced a new version of USB (version 2.0) which will allow bandwidth up to 480 megabits per second. In real-world computing terms, that means you could transfer a 60-megabyte file in one second across the cable. The current incarnation of FireWire has a maximum transfer speed of 400 megabits, or 50 megabytes in one second.

Both of these are more than what is required for digital video, which is a paltry 3.6 megabytes per second. However, USB 1.1 (the current standard) only has a maximum throughput of 1.25 megabytes per second, which means it cannot support digital video. Digital videocameras (and still cameras) are coming equipped with USB ports, but these are used only to transfer still pictures, not video.

The introduction of USB 2.0 changes things a bit - suddenly FireWire has some competition. Several third-party manufacturers such as ADS technologies, Western Digital, Adaptec and OrangeMicro are quick off the starting line to market USB 2.0 add-on cards for computers, but there are relatively few new USB 2.0 devices to plug the new cards into.

The essential question USB 2.0 raises for computer users, especially users of digital video is, do I need to upgrade to USB 2.0?

The answer to this question will depend on the technology trends of the future. Camcorder manufacturers such as Sony, JVC, Canon and Panasonic have all embraced FireWire technology as the standard for transferring digital video, but a radical sales job by USB vendors could convince them that a single USB 2.0 port could do an ample job of transferring both stills and video to a computer and effectively replace a FireWire port. Similarly a pitch by FireWire vendors could convince television and VCR vendors that FireWire ports can benefit these technologies by allowing camcorders to connect directly, and remove the outdated composite and S-Video ports from the camcorder.

Either way, it is unlikely that FireWire will be overly threatened by USB 2.0 - in fact, FireWire has already proposed the 1394A standard, which will allow a staggering 800 megabits per second, or the ability to transfer a 100-megabyte file across the cable in just one second. Technology makers like stability, and FireWire has become firmly entrenched in the world of digital video. Competition is invariably good for the consumer, either through advances in technology or reductions in price.

So when will you need to upgrade to USB 2.0? When you buy a device that requires a USB 2.0 connection!