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Making Connections: Considering New Thunderbolt Capture Devices

Media pros have seen data protocols come and go over the years. Some, like Fibre Channel, are still current fixtures, while others, such as SCSI, have bitten the dust. The most exciting new technology is Thunderbolt, which began development at Intel under the code name Light Peak.

The current implementation of Thunderbolt, a merger of PCI Express and DisplayPort technologies co-developed by Intel and Apple, is a bi-directional protocol that passes power, video display signals and data, with up to 10 Gb/s throughput in both directions. According to Apple, that’s up to 12 times faster than FireWire 800. It’s also faster than Fibre Channel, which tends to be the protocol of choice in larger facilities. In addition to data, peripherals can access 10 watts of power through Thunderbolt.

Like SCSI and FireWire, Thunderbolt devices can be daisy-chained with special cables. Up to six devices can be connected in series, but certain devices have to be at the end of the chain. This is typically true when a PCIe-to-Thunderbolt adapter is used.


A single signal path can connect the computer to external storage, displays and capture devices, which provides editors a powerful data protocol in a very small footprint. Thunderbolt technology is currently available in Apple iMac, MacBook Air, MacBook Pro and Mac Mini computers, and it’s starting to become available on some Windows systems. It is not currently available as a built-in technology on Mac Pros, but you can bet that if there’s a replacement tower, Thunderbolt will be a key part of the engineering design.

By its nature, Thunderbolt dictates that peripheral devices are external units. All of the processing horsepower of a PCIe card, such as a KONA or DeckLink, is built into the circuitry of an external device, which is connected via the Thunderbolt cable to the host computer. I tested three Thunderbolt capture/output devices for this review: AJA Io XT, Blackmagic Design UltraStudio 3D and Matrox MXO2 LE MAX. AJA added the monitoring-only T-Tap at NAB, which joins Io XT in AJA’s Thunderbolt lineup. Blackmagic Design has developed four Thunderbolt units at difference price tiers. For smaller installations or mobile environments, UltraStudio Express, Intensity Shuttle Thunderbolt and Intensity Extreme are viable solutions.

Matrox has taken a different approach by using an adapter. Any of its four MXO2 products—the standard MXO2, Mini, LE or Rack—can be used with either Thunderbolt or non-Thunderbolt workstations. Simply purchase the unit with a Thunderbolt adapter, PCIe card and/or ExpressCard/34 slot laptop card. The MXO2 product is the same and only the connection method differs, providing maximum flexibility. The fourth company making Thunderbolt capture devices is MOTU. MOTU’s HDX-SDI was not available in time for this review, but I did have a chance to play with one briefly on the NAB Show floor last month.

Differentiating Features

All three of the tested units include up/down/cross-conversion between SD and HD formats and perform in the same fashion as their non-Thunderbolt siblings. Each has pros and cons that will appeal to various users with differing needs. For instance, the AJA Io XT is the only of these devices with a Thunderbolt pass-through connector—the others have to be placed at the end of a Thunderbolt path. They all support SDI and HDMI capture and output, as well as RS-422 VTR control. Both the AJA and Blackmagic units support Dual Link SDI for RGB 4:4:4 image capture and output. The Matrox and AJA units use a power supply connected via a four-pin XLR, which makes it possible to operate them in the field on battery power.

Blackmagic Design UltraStudio 3D (rear)

The need to work with legacy analog formats or monitoring could determine your choice. This capability represents the biggest practical difference among the three. Both the MXO2 LE and UltraStudio 3D support analog capture and output, while there’s only analog output from the Io XT. The MXO2 LE uses standard BNC and XLR analog connectors (two audio channels on the LE, but more with the MXO2 or Rack), but the other two require a cable harness with myriad small connectors. That harness is included with the Blackmagic unit, but with AJA you need to purchase an optional DB-25 TASCAM-style cable snake for up to eight channels of balanced analog audio.

One unique benefit of the Matrox products is the optional MAX chip for accelerated H.264 processing. In my case, I tested the MXO2 LE MAX, which includes the embedded chip. When this unit is connected to a Mac computer, Apple Compressor, Adobe Media Encoder, Avid Media Composer, Telestream Episode and QuickTime perform hardware-accelerated encodes of H.264 files using the Matrox presets.

Fitting into Your Layout

I ran the Io XT, UltraStudio 3D and MXO2 LE through their paces connected to a friend’s new, top-of-the-line Apple iMac. All three deliver uncompressed SD or HD video over the Thunderbolt cable to the workstation. Processing to convert this signal to an encoded ProRes or DNxHD format will depend on the CPU. In short, recording a codec like ProRes 4444 will require a fast machine and drives. I haven’t specifically tested it, but I presume this task would challenge a Mac Mini using only internal drives!

Matrox MXO2 LE MAX

The test bed iMac workstation was configured with a Promise Pegasus six-drive RAID array. The iMac includes two Thunderbolt ports and the Pegasus array offers a pass-through, so I was able to test these units both directly connected to the iMac and daisy-chained onto the Promise array. This system would allow the connection of more Thunderbolt storage and/or a secondary computer monitor such as Apple’s 27” Thunderbolt Display. Most peripheral manufacturers do not automatically supply cables, so plan on purchasing extra Thunderbolt cables ($49 for a six-foot cable from Apple).

These units work with most of the current crop of Mac OS X-based NLEs, but you may need to choose a specific driver or software set to match the NLE you plan to operate. For instance, AJA requires a separate additional driver be installed for Adobe Premiere Pro or Avid Media Composer, which is provided for maximum functionality with those applications. The same is true for Matrox and Media Composer. I ran tests with Apple Final Cut Pro 7, FCP X and Premiere Pro CS5.5 but not Media Composer 6, although the units work fine with that application. Only the Blackmagic Design products, like the UltraStudio 3D, will work with Blackmagic DaVinci Resolve. In addition to drivers, the software installation includes application presets and utility applications. Each build includes a capture/output application that lets you ingest and lay off files through the device independent of an editing application.

Broadcast Monitoring and FCP X

The biggest wild card right now is performance with Final Cut Pro X. Broadcast monitoring was a beta feature added in the 10.0.3 update. With the release of 10.0.4 and compatible drivers, most performance issues have stabilized, so this feature is no longer considered beta. Separate FCP X-specific drivers may need to be installed, depending on the device.

If you intend to work mainly with Final Cut Pro “legacy” or Premiere Pro, then all of these units will work well for you. On the other hand, if you’ve taken the plunge for FCP X, I would recommend the Io XT. I never got the MXO2 LE MAX to work with FCP X (10.0.3) during the testing period, and initially UltraStudio 3D wouldn’t work either, until the later version 9.2 drivers that Blackmagic posted mid-March. Subsequent retesting with 10.0.4 and checking out these units at NAB indicate that both the Blackmagic and Matrox units work well enough. There are still some issues when you play at fast-forward speeds, where the viewer and external monitor don’t stay in sync. I also checked the MOTU HDX-SDI device with FCP X in MOTU’s NAB booth. Performance seemed similar to that of Matrox and Blackmagic Design.

Io XT was very fluid and tracked FCP X quite well as I skimmed through footage. FCP X does not permit control over playback settings, so you have to set that in the control panel application (AJA) or system preference pane (Blackmagic Design and Matrox) and relaunch FCP X after making changes. The broadcast monitoring feature in FCP X does not add any new VTR control or ingest capability and it’s unlikely that it ever will. To ingest videotape footage for FCP X using Io XT or UltraStudio, you will have to use the separate installed capture utility (VTR Xchange or Media Express, respectively) and then import those files from the hard drive into FCP X. Going in the other direction requires that you export a self-contained movie file and use the same utility to record that file onto tape. The Matrox FCP X drivers and software currently do not include this feature.

The image on the Panasonic professional monitor I was using in this bay matched the FCP X viewer image on the iMac screen using either the Io XT or UltraStudio 3D. That attests to Apple’s accuracy claims for its ColorSync technology.

Performance with Mainstream NLEs

Ironically, perhaps, the best overall performance was with the end-of-life Final Cut Pro 7. All three units were incredibly responsive on this iMac/Promise combo. For example, when you use a Mac Pro with any FireWire or PCIe-connected card or device, energetic scrubbing or playing files at fast-forward speeds will result in the screen display and the external output quickly going out of sync with each other. When I performed the same functions on the iMac, the on-screen and external output stayed in sync with each of the three units. No amount of violent scrubbing caused it to lose sync. The faster data throughput and Thunderbolt technology enabled a more pleasant editing experience.

I ran these tests using a direct run from the iMac’s second Thunderbolt port, as well as looped from the back of the Promise array. The connection method didn’t seem to make much difference in performance with ProRes and AVCHD footage. I believe you get the greatest data throughput when you are not daisy-chaining devices, but I doubt you’ll see much difference under standard editing operation.

The best experience with Premiere Pro was using the Matrox MXO2 LE MAX, although the experience with the AJA and Blackmagic Design devices was fine, too. This stands to reason, as Matrox has a strong track record developing for Adobe systems with custom cards, such as the Matrox Axio board set. Matrox also installs a high-quality MPEG-2 I-frame codec for use as an intermediate preview codec. This is an alternative to the QuickTime codecs installed on the system.