PortAudio.jl is a wrapper for [libportaudio](http://www.portaudio.com/), which gives cross-platform access to audio devices. It is compatible with the types defined in [SampleTypes.jl](https://github.com/JuliaAudio/SampleTypes.jl), so it provides `PASampleSink` and `PASampleSource` types, which can be read from and written to.