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Digital audio workstations

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open-ephys edited this page Feb 20, 2012 · 7 revisions

Ableton screenshot

Digital audio workstations (DAWs) such as Ableton Live (shown above) are a major source of inspiration for the GUI.

Here are some facts about DAWs (with respect to software for electrophysiology):

  • Their basic data format is comparable. Electrophysiology applications typically record neural data at 30 kHz with 16-bit resolution. DAWs record audio data at 44.1 kHz with 16 or 24-bit resolution.
  • They deal with similar channel counts. In neuroscience, 16 to 32 channels of simultaneous acquisition is typical. 100+ channels is less common, but the best systems have to handle it. In audio recording, a typical band will record with 10-20 microphones or line-ins. But the best DAWs need to be able to handle a symphony, which may require over 100 inputs.
  • Alternate data formats are nearly identical. Electrophysiologists deal with event-like inputs and outputs in the form of TTL pulses. Musicians deal with event-like inputs and outputs in the form of MIDI signals. Both TTLs and MIDI events are used to interface with external hardware. Many neuroscience and audio applications also include a synchronized video feed.
  • The online processing requirements for DAWs are much more intense. Software signal chains for electrophysiology typically include a simple bandpass filter and a spike detector. Software signal chains for audio recording routinely involve synthesizers, reverb, compressors, phasers, echoes, amplifiers, bit-crushers, and auto-tuners, just to name a few. Each must be processed in real time, all while other data streams are being read from disk, loaded from memory, and subjected to an entirely different set of filtering operations. On top of all this, the raw data must remain in editable form; in neuroscience, once the data is saved, it should never be altered.
  • DAWs are much more widely used. We don't have exact numbers for this, but given how many more musicians there are than electrophysiologists, it should come as no surprise. As a consequence, DAWs are much more mature, much easier to use, and much more flexible than ephys applications. In addition, a DAW license costs hundreds of dollars, rather than tens of thousands of dollars. While we recognize this is due entirely to economies of scale, it still made us jealous enough to try and replicate some of the functionality of DAWs within our GUI.

For these reasons, the fact that Juce already contained a complete set of audio processor classes made it the obvious choice for our C++ library.

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