DAWr

DAWr (pronounced "door") is an audio playground for people who like to write Rust code. It has some features of a simple DAW, including a build-in wavetable synthesizer, sampler, and basic audio effects. However, it's still missing a lot: there's no equalizer, the sampler only works in one-shot mode, and more. I don't plan on adding new features for the time being, but I'd appreciate suggestions and pull requests!

The feature set is limited, but it's enough to make a shitty future bass drop section in Rust! You can find code for this in src/bin/demotrack.rs. Here's what it sounds like (on SoundCloud).

WARNING: This library doesn't have any unit tests! There are probably bugs!

Devices

In this library, devices are things that emit a signal, which can either be mono or stereo. Stereo is usually audio, and mono is usually some kind of control parameter. There are two important traits, MonoEmitter and StereoEmitter for devices which output mono or stereo respectively. There is also an EventSource type representing a collection of events that occur at specific moments in time (e.g. NoteOn(frequency) and NoteOff). The philosophy is that each device should do one simple thing well, and then more powerful devices can be created by chaining simpler ones.

New devices are constructed by providing references to all of their input devices and references to all of the event sources they need to listen to. For example, to build the MonoSynth device, it needs to be provided references to an Oscillator (a MonoEmitter which tells it what its current phase in the wave is), another MonoEmitter to tell it which wave of the wavetable is selected at the current moment in time, and another MonoEmitter specifying the amplitude envelope. In order to get notes to play, the amp envelope device will listen to an EventSource<NoteEvent> and output a non-zero amplitude value during the notes. We use Rust's Rc pointers extensively, so multiple devices can use the same device as input.

Here is a list of all the built-in devices:

Mono Sources

• ConstSignal: Outputs a constant-valued mono signal.
• Envelope: Listens for NoteOn events and outputs 0.0 when there are no notes playing and 1.0 while a note is playing.
• Oscillator: For use with MonoSynth, outputs the current phase of the wave being played.

Instruments

• MonoSynth: A monophonic wavetable synthesizer. You can create polyphony and unison by using more than one instance along with the Pan effect and the MonoSynth's Oscillator's detune parameter.

• Sampler: Listens to an EventSource<SamplerEvent> and plays some audio whenever it sees a Play or PlayAtSpeed(speed) event. In the latter case, the playback is sped up by a factor of speed (by skipping over or duplicating samples).

Effects

• Mixer: Sums the outputs of multiple stereo inputs.
• Gain: Multiplies a stereo input signal with a mono input signal.
• Pan: Adjusts the balance of a stereo signal according to a mono input signal in the range [-1, 1].
• MonoToStereo: Duplicates a mono signal to both channels of a stereo signal.
• StereoToMono: Sums the left and right channels of a stereo input to create a mono signal.
• WaveShaperEffect: Applies waveshaping (e.g. hard clipping) to a stereo signal.

Wishlist

This library is missing some really important stuff, like:

• High-pass and low-pass filters.
• An equalizer.
• MIDI support.
• A polyphonic synth device that listens to MIDI events, based on MonoSynth.
• Unit tests.