AJA has been producing some of the best video capture cards in the industry for several years, including the Kona 2 and Kona 3 series, which have been available in several flavors to accommodate differing PCI bus architectures and SD and HD video formats. The company also broke serious ground with the "Io" SDI FireWire interface. The product reviewed here, the Io HD, is the newest FireWire-based product. It was designed in close cooperation with Apple to use the ProRes422 codec to handle high-quality HD video over a FireWire bus and interface. The purpose of the product is to give Final Cut Studio users a complete HD/SD analog/digital video/audio ingest to finishing interface that is compatible with both desktop and laptop computers via FireWire.

Physically, the AJA Io HD is a box that connects to a Macintosh computer via a FireWire 400 or 800 connector. It contains a very full set of input and output connectors suitable for all flavors of digital and analog video and audio. The two sets of SDI connectors and one set of analog component connectors can be set for SD or HD. In addition to the composite and S-video I/Os, there is HDMI video w/8-channel audio I/O, embedded SDI 8-channel audio I/O, AES/EBU 8-channel (BNC) unbalanced audio I/O, analog 4-channel balanced audio I/O (XLR), and analog 2-channel unbalanced audio output (RCA). There is also genlock with loop through, RS-422 machine control and an LTC timecode I/O. The outputs work simultaneously and perform 10-bit, real-time, up/down/cross-conversion in hardware.

Because it was designed with Apple ProRes422 in mind, AJA Io HD contains hardware that supports the ProRes codec specifically. On install it provides a large set of ProRes "Easy Setups." The ProRes codecs run at 145 Mbps and 220 Mbps, respectively, which is within the bandwidth of a FireWire bus. At this level of throughput, it will work on either a FireWire 400 or FireWire 800 connection; both cables come with the box. The device also currently supports Apple Motion and Adobe After Effects. Apple Color is currently supported for SD only and Adobe Premiere is not supported at this time.

The most efficient workflow for the system is to capture video through the AJA Io HD into a ProRes422 format and stay in that format throughout your project. This is what the box is designed to do and it does an excellent job when used this way.

Not all other formats and workflows are compatible, however. Non-ProRes422 clips get transcoded on the fly to ProRes for playback. Depending on the native format of the clip and the available processing power of the computer, this may or may not result in smooth playback through the Io HD. Long-GOP formats, such as Sony XDCAM EX, will not play back natively, even on a beefed-up four-processor MacPro. This means that many non-ProRes422 clips cannot be played back over the Io HD until they are dropped into a ProRes422 sequence in Final Cut Studio, effectively disabling video output from the clip viewer. You can still view and edit clips on the desktop, but not with continuous video output. (You can solve this problem by converting the files, but it can be time consuming, depending on the files and equipment.)

Whether you would use this box for a studio setup depends on how the Io HD compares to PCI card-based solutions in performance, price and flexibility. Because PCI card solutions, including AJA’s Kona 3 series, are not limited by the relatively narrow throughput of the FireWire bus, they generally let you work in more high-bandwidth formats natively. The FireWire bus also introduces a 2- to 4-frame lag between the desktop and the video display. If you are using a different device for audio output, such as a PCI card-based audio interface, there is currently no supported solution for dealing with the video delay. Also, if you are already using a Kona 2 or Kona 3 card, the devices are incompatible with the Io HD in the same system. Installing the Io HD drivers will disable the Kona card.

The Io HD is a great solution for users who need flexible, portable hardware that sets up easily on a laptop or desktop. The hardware has many conveniences and features, including up/down transcoding, that will be useful and fit many needs. For other situations, such as audio post, where lag could be an issue, or high-end video post, where you may want more access to high-bandwidth formats, a PCI-based solution, such as the Kona 3, would be a better choice.