Will Head
Video editing needs more processing clout than ever, but don’t despair: there are some devices that can take the strain from your Mac’s CPU…
As technology advances, tasks that would previously have your Mac wheezing and unusable become activities that can run in the background while you’re getting on with other things. Tasks, that is, that don’t involve manipulating video.
There’s no getting away from the fact that video information occupies a huge amount of data and even the simplest of operations means some intense mathematics. This problem is further exacerbated by the fact that video resolutions keep increasing.
By the time Macs just about had enough oomph to process standard definition without breaking into a sweat, the world moved to high definition. You can’t even escape HD if most of your work is online – increased broadband speed and the HD capabilities of video sharing sites such as Vimeo and YouTube mean outputting those extra pixels is a must.
Even if you only ever had to output in SD, the pool of cameras on the market that aren’t HD is rapidly diminishing. While you can always capture in a lower resolution, many cameras are increasingly using formats based on modern codecs such as AVCHD, which are space efficient for footage but require a lot more processing power to decode and edit.
If you only ever need to edit while sitting at a desk then you can throw money at the problem and bag yourself an eight-core machine, but even that’s not an efficient use of all that computer power. If you’re shopping for a laptop then the amount of processor clout available is much more limited.
Part of the problem is that computers can do many, many things, and crunching through video is just one of them. The result of this is a machine that’s a jack of all trades, master of none. You can still achieve the task you want, but it takes time as the software has to work around the limitations of the hardware.
While it’s not impossible to design a chip with lighting-fast, dedicated video processing, it would only be fast at a single format – throw a different video file at it and it’ll slow to a crawl again. Fine if you’re an expert at predicting the future, but, given the huge lead times in processor development, more troublesome if you build in support for a format that rarely gets used.
However, it’s not all bad news. Nvidia has started to turn some of the graphics processing might in its cards to video use through its Compute Unified Device Architecture (Cuda) programming interface, which lets application developers tap into the power of its GPUs. At present, this is limited to a few desktop cards, but it can provide a considerable speed boost to supported applications. Adobe’s latest version of Premiere Pro, CS5, for example, can offload some of the video processing to an Nvida card, which frees up the CPU for other tasks. The result is a significant boost in performance.
Another option is to pick a specific video format and then design some hardware to specifically speed up processing it, which is precisely what Elgato has done with its Turbo.264 HD USB stick. It looks like an oversized USB thumb drive, but inside it is a dedicated H.264 encoder so it can process video much faster than your Mac’s CPU. Simply plug it into a spare USB port and fire up the supplied application. Drop in the file you want to convert to H.264 format and watch it speed by.
Once you’ve picked a file, you can then choose from a number of presets – from iPod to 1080p HD – and click Start. You can also create your own presets and queue up further files first and let the application process them as a batch. If you’re encoding more than one file, you also have the option of combining everything into a single file, which is useful if you want to add standard titles, idents or end stings in one go.
The application also installs a QuickTime component on your system so you can use the Turbo.264 stick when exporting from other applications, too, such as Final Cut Pro.
The bundled application is fine if you’ve got a batch of videos you want to process into H.264 format, but it’s the integration with Final Cut and other QuickTime applications where the Turbo.264 really comes into its own. By tapping into its hardware-accelerated encoding directly, you can output from the timeline in double-quick time without any intermediary steps. It’s not perfect, but it works.
To use the Turbo.264 engine inside Final Cut, instead of sending your sequence to Compressor choose Export > Using QuickTime Conversion. You can then pick Elgato Turbo.264 HD and select which preset you want by clicking the Options… button. Hit Save and sit back – but not for too long – while the accelerated export kicks in. It’s also possible to access the Turbo.264 QuickTime component from Compressor, but the integration is a little awkward – for example, it didn’t seem possible to create multiple settings profiles and the output results proved a little unpredictable. Given the choice, exporting via QuickTime is a much easier and reliable option.
There’s no support for Premiere Pro, so you’ll still need to export to another format first before you can speed things up. If you need to produce a few different versions, such as for HD, SD and iPod, then it’s still a time-saver. Pick a quick format to output from Premiere and then load that into the Elgato application for further batch processing.
To get an idea of the performance increase you can expect, I timed how long it took to encode a single 48-second, 1080i ProRes LT file in the Elgato app, from Final Cut using QuickTime export and finally from Final Cut using the accelerated Turbo.264 export. Since there were no edits or effects, this just shows the export time – for complicated sequences with lots of transitions and effects, you’d also have to consider how long it takes Final Cut to process those before it starts encoding the video to H.264 format. I created three output formats: 1080p, 720p and 640 x 360 suitable for playing on an iPod.
The straight export from Final Cut took two minutes 19 seconds, one minute 31 seconds and one minute three seconds for each format respectively. This works out as a frame rate of 9fps for 1080p, 13fps for 720p and 19fps for iPod. Switching to accelerated export in Final Cut speeded up things considerably, with the three files taking 45 seconds, 35 seconds and 25 seconds for 1080p, 720 and iPod respectively. This works out at 27fps for 1080p, 34fps for 720p and 38fps for iPod.
Results for the standalone Elgato app were almost identical, with 1080p taking 44 seconds (27fps), 720p 37 seconds (33fps) and iPod 27 seconds (45fps).
The difference between normal and accelerated export was around three times in this case, using a 3.06GHz Intel Core 2 Duo MacBook Pro with 4GB of Ram. The faster your Mac, the less drastic the speed increase will be, but it’s still likely worthwhile, especially given the price. The Turbo.264 HD has a list price around £140 (£119 ex VAT), but at the time of writing you could pick it up on the Apple Store for £89.95 (£76.55 ex VAT), which is an absolute bargain compared with the cost of upgrading your machine.
The Elgato application also has another trick up its sleeve: the ability to transcode AVCHD footage straight from a camcorder. AVCHD format can be particularly troublesome for computers to process, as it’s designed for recording material rather than editing it. Not only can you encode material straight from a camcorder, but you can even perform basic editing – trimming clips, say – first. You can encode all the clips separately or combine them into one output file.
If you output a lot of H.264 material, the Turbo.264 stick is a great time-saver. It would be great if it could hook into Premiere Pro the way it integrates with Final Cut, but even so it’s still a useful tool to have around to speed things up when there’s a deadline is looming.