AAX or “Avid Audio eXtension” is a plug-in format developed by Avid, the company behind the hugely-popular Pro Tools audio recording and editing system. AAX replaces the older Pro Tools plug-in formats TDM, RTAS, and AudioSuite.
With AAX, Avid aimed to provide a unified plugin format that was capable of 64-bit processing. Its release came on the heels of the 64-bit version of Pro Tools, which required a plug-in format suited to its capabilities.
AAX comes in two versions: AAX DSP and AAX Native. The format enables users to transfer sessions between native and DSP-accelerated Pro Tools systems, and still have access to the same plug-ins.
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AAX: a more efficient plug-in format
There are a number of good reasons why AAX are a better alternative to the older plug-in formats. As with all other 64-bit capable software, AAX plugins will be able to make full use of the available RAM in a given computer system. In contrast, 32-bit plugins can utilize only a maximum of 4 GB. With AAX, users will be able to utilize more effects and more virtual instruments in their sessions.
AAX–a logical step forward
The rationale behind the development of AAX was laid out by developer Paul Neyrinck and Avid’s Dave Tremblay. According to Paul, AAX was borne out of the need for a plug-in format that worked with both native and DSP systems. Avid was compelled to develop AAX, given the fact that only Steinberg could modify the VST format for DSP support, and that only Apple could do the same for its AU format.
Dave Tremblay added that AU–being a Mac-only format–left Windows users with no option but to use VSTs. Considering the absence of processing code suitable for DSP operation, he cited the need for a format that wouldn’t be limited to native applications. He further explained that VSTs don’t scale up favorably to large sessions, due to the way they handle automation.
Pro Tools users that aren’t quite ready to give up on their TDM plugins and RTAS plug-ins will be glad to know that AAX maintains compatibility with the older formats. Even older sessions can be opened without issues, going as far back as Pro Tools 9. This wouldn’t have been possible with the VST format, because of the incompatibility with the data stored in Pro Tools sessions.
Another factor that played a part in the development of the AAX format was Avid’s desire to remain an industry innovator. As Dave said, sticking with the VST format would have limited the company’s flexibility with regard to plug-in platform innovation, and would have hindered the development of the Pro Tools engine itself. By developing the AAX format, Avid was able to produce plug-in such as AAX Hybrid, which processes audio using DSP hardware and the native processor at the same time.
AAX now and in the future
At present, it seems that Avid has pinned all its future development plans on AAX. As far as the company’s efforts in the 64-bit realm go, AAX is pretty much poised to remain the standard. Upcoming Pro Tools releases will most definitely be using the AAX format. Backwards compatibility with TDM and RTAS notwithstanding, Avid is clearly sticking with AAX for the long haul. The company also expects third-party developers to follow suit with their own 64-bit offerings.
The question that this now brings up is: what of the users of plug-ins that have yet to be released in AAX format? It might be a tough pill to swallow, but the reality is that Pro Tools 11 will only support 64-bit AAX plug-ins. This means that all plug-ins will have to be updated to 64-bit versions.
If all this seems a bit too much for you, it might be wise to hold off on upgrading to Pro Tools 11 until such a time as AAX support becomes the norm. Longtime users with an eye toward the future may also opt to run PT 10 alongside PT 11, so that they can still use their TDM and RTAS plug-ins while waiting for the right time to make the switch. And of course, you also have the option to migrate to PT 11, and switch out all your old plug-ins in favor of new AAX versions, all in one go.
You can find all AAX plugin versions in our VST and AU plugin guide.