Using Your Graphics Card To Process Plug-ins

If your PC struggles to run the plug‑ins you want to use, how about shifting some of the load to its graphics card?

In my PC Notes column for October 2008's SOS, I mentioned a novel convolution reverb plug‑in from Nils Schneider (http://nilsschneider.de/cms) that runs not on the native processor of your motherboard, but on the GPU (Graphics Processing Unit) chip found in many NVidia graphics cards. Essentially, it operates rather like dedicated audio DSP hardware from companies such as Focusrite, TC Electronic and Universal Audio: if your native processor is struggling, you just offload some of your processing requirements to your graphics card! Since then, Nils has been joined by a couple of other audio developers, so let's look more closely at this novel phenomenon.

Convolution Revolution

CUDA (Compute Unified Device Architecture) is a parallel computing language, a version of the 'C' programming language with special NVidia extensions, developed by NVidia for their GPUs from the G8X and up. NVidia graphics cards such as this GeForce model are being pressed into service to provide extra processing capacity — and now audio software producers are getting in on the act.It works with their GeForce, Quadro and Tesla graphics cards, and will apparently run without modification on all future NVidia graphics cards. The beauty of the GPU is that, unlike the dual or quad‑core format of today's standard PCs, it has a "parallel many‑core architecture, each core capable of running thousands of threads simultaneously”.

Convolution reverbs are prime candidates for such a processor, since they require many thousands of similar calculations to be made, so it's hardly surprising that the second audio product available in a CUDA edition is another convolution reverb, this time from LiquidSonics (www.liquidsonics.com). Their Reverberate LE is donationware and is available in both native and GPU editions, although its developers do warn that, depending on which NVidia graphics card and CPU you're using, you may find the native version more efficient, especially when using smaller audio buffer sizes for lower latency. This is due to the extra processing overhead of ferrying blocks of data to and from the GPU. Acustica Audio's Nebula 3 commercial effects plug‑in (www.acusticaudio.net) also has optional CUDA‑based optimisations for those with suitable graphics hardware. Although, strictly speaking, its effects are based on 'Volterra kernels', you can, in practice, consider them a form of dynamic convolution.

CUDA is already popular with game developers, and graphics and other digital content creators, but NVidia are keen to offer help to audio developers who want to explore its possibilities. They have a CUDA Zone web site (www.nvidia.com/object/cuda_home.html) offering information, advice and downloadable toolkits. It does seem ironic that musicians are routinely advised to buy modest graphics cards because they don't need fast 3D calculations or the associated noisy cooling fans, but the faster NVidia cards are now being used to run more audio plug‑ins!

Directory Report

Musicians with large collections of audio files and samples often run out of drive space, and in PC Notes February 2009 I recommended several utilities to help them discover what's taking up the most space and locate duplicate files that could be deleted. Well, thanks to developer Allan Braun, I can now recommend another utility that combines both functions, and makes easier reading when you've got hundreds of folders.

AMB Software's Directory Report (www.file‑utilities.com) looks like a deluxe version of Windows Explorer, but always shows the folder content size in addition to the usual information. It may look like Windows Explorer, but AMB Software's Directory Report offers many additional features that would be invaluable to musicians.However, its title bar provides lots of other options. These include name filters, so that you can, for instance, narrow down your search to WAV or MP3 files, and 'compare' directories, which are very useful if you think you've installed the same application or library in two or more locations.

You can sort the display in various ways, the most useful being by total size of folder contents. Particularly handy is the Largest files or directories option, which opens a new display showing the largest files or directories. This is great for finding out what's eating most of your drive space! You can also search for duplicate files or directories.

In all, Directory Report is a most useful tool and has a trial version that's fully functional for 10 days. The full version costs just £17$25.