portaudio.scm

MIT Scheme bindings for PortAudio

Building and Installation

I've only tested this on Linux.

First build and install PortAudio (for Mac or Linux).

Then cd into the portaudio.scm directory and build the MIT Scheme bindings:

make
sudo make install

Then load PortAudio and play around:

(load "portaudio.scm")
(define win (window))

;; Input streams
(plot win (input-stream) "black" 50 25)

;; Output streams
(clear win)

(define a (sine 'a))
(define c (sine 'c))
(plot win (splice a c) "black" 1 0.5)

(define ac (splice (wave:+ a c)))
(plot win ac "red" 1 0.5)

(output-stream ac)

Usage

See the PortAudio API documentation

PortAudio can be used synchronously with read-stream and write-stream or asynchronously with read and write callbacks. Callbacks are messy and the FFI trampolines are slow; stick to sync for now.

If you desperately want to use callbacks, switch the commenting in stream.scm and in portaudio.cdecl and rebuild the whole project. Then you can pass callbacks (procedures of five arguments) into (open-stream).

Synchonous read/write:

(define stream (open-default-stream))
(start-stream stream)
...
(write-stream stream buffer)
(read-stream stream)

Asynchronous read/write with callbacks:

(define (kappa input output frame-count time-info status-flags)
  ...)
(define stream (open-default-stream kappa))
(start-stream)