A Peripheral in the Palm of Your Hand: Testing AJA’s Thunderbolt-Enabled T-Tap
Thunderbolt is the latest protocol for peripherals used by Apple on its computers to carry audio, video, data and power over a single cable. The protocol combines Apple’s DisplayPort technology and PCIe into a single connectivity path. The technology can be used to daisy-chain numerous devices, including storage, monitors and broadcast I/O hardware. Thunderbolt ports are currently available on Apple MacBook Air, MacBook Pro, Mac mini and iMac computers. Manufacturers such as AJA Video Systems, Blackmagic Design and Matrox have embraced Thunderbolt technology and have engineered a number of capture and output devices for it.
The newest Thunderbolt unit to hit the market is the T-Tap from AJA. T-Tap follows AJA’s previously released Io XT, which delivered much of the power of AJA’s popular KONA cards in a Thunderbolt-enabled external unit. While Io XT packs a lot of punch in a small, lightweight unit, there was market demand for an even smaller product. Thus came the T-Tap, a small, robust external adapter designed only for broadcast output and monitoring. Without having to accommodate input electronics, engineers were able to reduce the unit’s dimensions to that of a deck of cards. It is ideal for the editor who just needs to connect his laptop or iMac to an external monitor or recording deck.
The AJA T-Tap is a bus-powered, end-of-chain Thunderbolt product. This means it has to be last in a series of Thunderbolt devices. For example, if you were using a Thunderbolt-enabled Promise Technology Pegasus RAID storage array, T-Tap could be connected to the Pegasus’ looped Thunderbolt output port. Both storage and T-Tap would be connected in a serial path from the single port on a MacBook Pro. In the case of an iMac with dual Thunderbolt ports or when using FireWire, USB 3.0 or internal storage, the T-Tap would be directly connected to the Mac. Neither type of connection is significantly faster at getting video out through the T-Tap due to Thunderbolt’s bidirectional 10 Gb/s throughput. Full bandwidth, uncompressed audio and video are sent over the single Thunderbolt cable to the T-Tap. In turn, the unit can be connected to any gear with SDI or HDMI connections (or both simultaneously). T-Tap is capable of passing 10-bit, uncompressed SD, HD and even 2K (2048 x 1080) video with up to eight channels of embedded 24-bit digital audio.
Setting up the T-Tap Configuration
I tested the AJA T-Tap connected to an Apple 17” MacBook Pro 2.2GHz Core i7 running OS X 10.8.2. The unit was directly connected to the laptop’s Thunderbolt port, with Apple ProRes LT media playing from an external G-Technology G-DRIVE mini. The G-DRIVE mini was connected to the laptop and bus-powered using the FireWire 800 port. The T-Tap’s SDI output was connected to a TVLogic monitor, while the HDMI was simultaneously connected to a Panasonic plasma display.
Currently the T-Tap works with a variety of editing hosts, including Avid Media Composer/Symphony/NewsCutter (6.5/10.5), Apple Final Cut Pro 7/X and Adobe Premiere Pro CS6. AJA does not employ a unified installer, so the basic driver software package that you download enables the unit to work with Apple products. Use with Adobe or Avid systems requires the download of additional plug-ins. The package also includes a number of AJA utilities, such as software to output QuickTime media files through the T-Tap without having to launch an NLE application. T-Tap does not work with Autodesk Smoke 2013 (yet), nor does it work with DaVinci Resolve, since Blackmagic Design restricts output to its own products.
T-Tap setup is controlled through the AJA Control Panel. If you’ve used AJA’s other products—KONA cards, for example—then you’ll be familiar with its use. I did my testing with FCP 7 and FCP X. Under the “legacy” version of Final Cut Pro, you have quite a lot of direct control over video output using FCP’s pull-down menu for playback and viewing. With FCP X, you have to set the format that matches your editing timeline in the AJA Control Panel before launching FCP X. T-Tap is intended for monitoring and synchronous output only, so there is no VTR control port on the unit. You can certainly “roll and record” a deck on the fly, but there is no software control for frame-accurate output from any of the NLEs to a recorder.
T-Tap supports all of the popular video frame rates, as well as true 24, 30 and 60 fps. Video can be interlaced, progressive or progressive segmented frame (PsF), and the HDMI output supports both YUV and RGB video (host software-dependent). Generally the video is played simultaneously through both the SDI and HDMI ports, but some frame rate/scanning combos, such as 23.98 PsF, will not be compatible with HDMI and will display only on the SDI output.
Working with Projects
I found that some settings in the AJA Control Panel would sort of override the host NLE’s setting. This is especially true of FCP X. For example, I was playing a 23.98 timeline but had the T-Tap set to 29.97i output. It did display as a 1080i signal, but with a 2:2:2:4 rather than the proper 2:3:2:3 pull-down cadence added. When I played the same media in FCP 7 using a 1080p/23.98 sequence, but with the playback set to 29.97i in the FCP menu, the output and display used the correct pull-down cadence. This difference has less to do with the capabilities of the T-Tap and more to do with what the host software allows or takes advantage of. Although there is no secondary format (upconverted or downconverted) output, as with the KONA cards, you can set the primary playback to be downconverted from within the NLE software. Testing the same 1080p/23.98 sequence in FCP 7, I was able to change the playback settings to 720p/59.94 (downsampled and cadence inserted) and the T-Tap performed beautifully, just like a standard PCIe card.
A few other niceties are worth noting. You can add timecode overlays from the sequence’s timecode (“burn-in” windows) to the output. HDMI protocol can be set for HDMI or DVI when using an adapter for a DVI display. The RGB range can be set to full (0-1023) or SMPTE (64-940) levels. Settings can be saved or recalled from a presets window.
Scrubbing, skimming and playback were very responsive with either of the Final Cut applications. With Apple ProRes LT media, this hardware combo felt no less agile than a Mac Pro with fast storage and a PCIe card, like a KONA.
Overall, I found the T-Tap to be great little unit, but there are a couple of things to be aware of. First of all, the T-Tap doesn’t include its own Thunderbolt cable. This is typical of most manufacturers; you’ll need to factor in another $49 (Apple) for a cable. The T-Tap is also very warm to the touch. There’s a lot of processing going on, of course, but the T-Tap was considerably warmer than the G-DRIVE sitting right next to it. The AJA Io XT that I tested a few months ago felt cooler, but it is larger and uses a hard plastic case. A Thunderbolt device carries up to 10 watts of power, so metal was used in the smaller T-Tap’s enclosure to dissipate heat.
Sizing up the Competition
I would be remiss if I didn’t address the competition. AJA and Blackmagic Design often compete head to head by offering similar products. The AJA products are usually a little more expensive, as is the case here. T-Tap lists for $295, which is very affordable, but Blackmagic Design’s UltraStudio Mini Monitor is less. The relative price difference may sound like a lot, but it really isn’t, as both cost so little to start with.
Both companies make great products, but if either of these units is on your radar, then make sure you compare them as apples-to-apples with the features that are most important to you. The AJA T-Tap does include some notable features that you may need. There’s 2K output, RGB support to an HP DreamColor display and a three-year warranty. As someone who has dealt with AJA over the years on a few minor support issues, I can certainly attest to the fact that their customer response is one of the best in the business. That alone may be worth paying a few bucks more for.
As productions move into a file-based world and smaller, more capable computers can handle the load, we become less dependent on cards that you have to install into a workstation just to monitor your video. Yet the need to provide broadcast-quality monitoring and real-time output to recorders, routers, servers and switchers has not diminished. AJA has been a key part of this migration, offering the right products to serve video professionals. T-Tap continues the legacy. It’s small and robust, yet it packs a punch where it counts.
Product: AJA T-Tap
Pros: Robust broadcast monitoring adapter in a small form factor. Bus-powered Thunderbolt protocol. Simultaneous SDI and HDMI connections. Output up to 2K. Compatible with Avid, Apple and Adobe editing software.
Cons: Thunderbolt cable not included. The unit runs very warm. No analog audio output.
Bottom Line: A solid product for the editor on the road who needs the best quality digital video and audio output in a small, portable device.