Editing audio in Linux



Ardour attempts to stand next to the big boys of professional audio editing. Trying to compete with the likes of ProTools (which I'll use for comparison, since I'm more familiar with it than other DAWs) requires two main accomplishments: first, Ardour must be able to do everything the proprietary DAWs can do with comparable performance and ease of use. Secondly, and more speculatively, to become relevant Ardour must achieve market share; for any FOSS to be useful it has to be widely used. Otherwise, Ardour will not receive the community support required to keep such an ambitious project in development.

To get started, I looked at the Ardour manual, which is pretty well done, and should be, given that they hope to make money off it. A noticeable shortcoming was that there's no quick and dirty "here's how to edit and mix" for someone who's not a complete novice. Ideally, the GUI would make a certain amount of this obvious from the start, and Ardour does pretty well with that. Given that I used to use ProTools 5 quite a bit, it took me about 30 seconds to create a couple tracks and start editing. There are some notable novelties in Ardour's GUI, such as its very minimal menu bar, and heavy reliance on contextual menus. Ardour's approach to GUI takes a page from the Linux playbook (as well it should), and provides an interface that is extraordinarily quick and efficient, albeit a little difficult to learn at first (just take a look at the venerable Emacs and vi for other examples). For a Linux geek or an experienced audio producer this sort of interface is welcome.

Operations and performance were quick and snappy on my workstation, and left nothing to be desired. Normalizing a 45 minute interview took about 30 seconds. Throwing on some flange, pitch shifting, and heavy reverb pumped CPU usage up to a not-too-worrisome 10% during playback. As any Linux audio app should, Ardour uses the LADSPA (Linux Audio Developers' Simple Plugin API) plugin architecture. VST plugins may be used, but it can be hit and miss.

The requisite contrived screenshot of a busy session.
Notice the system performance meters in the upper right hand corner.

Ardour's plugin model highlights the generally modular FOSS approach to software. For example, Ardour doesn't offer any mastering and CD burning facilities, but instead easily interfaces with JAMin via Jack. Because FOSS is free, there's no impetus for developers to inhibit the use of third-party or competing software. The result of this modularity is much more capable software; rather than Ardour including a crappy mastering app, it leverages an existing project to do the job better. Importantly, this modularity provides a means to achieve radically more advanced software, since Ardour can interface with experimental and highly specialized software. An appropriate example is interfacing Ardour with Pure Data, a FOSS dataflow programming language that allows manipulation of audio in realtime.

Ardour isn't all sunshine and roses, however. (Here's where I try to get negative about something I am admittedly biased about.) Hardware is undoubtedly of primary concern to audio production, and Ardour, like every other piece of software ever written, doesn't support every piece of hardware ever made. Of concern are three types of hardware: the sound card, control surfaces, and specialized DSP hardware. Since Jack uses ALSA, any sound card that ALSA supports will work. ALSA has its own set of hardware support complications, but in general, support is pretty good and getting better all the time. As far as control surfaces go, MIDI surfaces that send transport controls over MMC are usable in Ardour. This includes a lot of hardware, though some fancier systems use more complicated protocols and aren't supported yet.

Support for dedicated DSP processors is somewhat controversial. A DSP processor is like a graphics card for audio—it can accelerate DSP operations, reducing the load on the main CPU. The problem here is that since DSP cards are such a niche market, the only ones available are proprietary add-ons for proprietary software. They use proprietary protocols, closed source, and are locked down to be used with only one piece of software, eg. ProTools. In the past, this has been a big issue, since mainboard CPUs could hardly handle the load of 32 tracks of audio, much less DSP in realtime on top of that. Applying an effect to a track required rewriting the track, which took expensive time and slowed down an otherwise fluid editing process. Nowadays, with an ordinary PC, dozens of tracks can be played and processed through filters in realtime without trouble. The argument against DSP hardware goes that with audio data becoming so easy to process, better results will be achieved by upgrading general purpose hardware, than by buying specialized hardware acceleration.

This is an interesting attitude, given the press for distributed processing models in the gaming world, what with video acceleration and now physics and AI hardware acceleration. Also interesting is a recent effort to utilize the GPU for DSP hardware acceleration. If such technology were to become commonly available, perhaps Ardour would come to rely on offboard DSP processing. Until then, the proprietary nature of available DSP hardware makes it highly unlikely that Ardour will support DSP cards.

If you can be convinced that commodity hardware will pack enough punch for your editing, Ardour delivers at the best cost of all: free. Free of monetary cost, free of guilt, and free as in freedom. But FOSS zealots have been trying to give away their completely serviceable software for decades without much success, and Ardour is no exception. Ardour may, arguably, be as good as any other DAW out there. However, learning a DAW can represent an enormous investment of time. As long as the industry continues to ignore apps like Ardour, that investment will turn away all but the most intrepid. Until it becomes practical for professionals to learn how to use an Ardour-based system, no one will care how amazing (or not) Ardour is.

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