racket-sound/libao.rkt

#lang racket/base

(require (prefix-in fin: finalizer)
         (prefix-in ffi: "libao-async-ffi.rkt")
         ffi/unsafe
         ffi/unsafe/custodian
         data/queue
         "private/utils.rkt"
         )

(provide ao-open-live
         ao-play
         ao-close
         ao-at-second
         ao-music-duration
         ao-bufsize-async
         ao-clear-async
         ao-pause
         )

(define device-number 1)

(define-struct ao-handle (handle-num
                          [bits #:auto #:mutable]
                          [bytes-per-sample #:auto #:mutable]
                          [byte-format #:auto #:mutable]
                          [channels #:auto #:mutable]
                          [rate #:auto #:mutable]
                          [async-player #:auto #:mutable]
                          [closed #:auto #:mutable]
                          )
  #:auto-value #f
  )


(define (bytes-for-bits bits)
  (/ bits 8))

(define (ao-open-live bits rate channels byte-format)
  (let ((handle (make-ao-handle device-number)))

    (fin:register-finalizer handle
                            (lambda (handle)
                              (ao-close handle)))

    (set-ao-handle-bits! handle bits)
    (set-ao-handle-bytes-per-sample! handle (bytes-for-bits bits))
    (set-ao-handle-byte-format! handle byte-format)
    (set-ao-handle-channels! handle channels)
    (set-ao-handle-rate! handle rate)
    
    (let ((player (ffi:ao_create_async bits rate channels byte-format)))
      (set-ao-handle-async-player! handle player)
      (if (eq? player #f)
          (begin
            (set-ao-handle-closed! handle #t)
            handle)
          (begin
            (set-ao-handle-closed! handle #f)
            handle
            )
          )
      )
    )
  )

(define (ao-close handle)
  (unless (eq? (ao-handle-async-player handle) #f)
    (ffi:ao_stop_async (ao-handle-async-player handle))
    (set-ao-handle-async-player! handle #f)
    )
  )

(define (ao-play handle at-time-in-s music-duration-s buffer buf-len buf-type)
  (let* ((bytes-per-sample (ao-handle-bytes-per-sample handle))
         (bits (ao-handle-bits handle))
         (rate (ao-handle-rate handle))
         (channels (ao-handle-channels handle))
         (endianess (ao-handle-byte-format handle))
         (buf-info (ffi:make-BufferInfo_t buf-type bits rate channels endianess))
         )
    (ffi:ao_play_async (ao-handle-async-player handle)
                       (exact->inexact at-time-in-s)
                       (exact->inexact music-duration-s)
                       buf-len
                       buffer
                       buf-info)
    )
  )

(define (ao-pause handle pause)
  (ffi:ao_pause_async (ao-handle-async-player handle) (if (eq? pause #f) 0 1))
  )

(define (ao-at-second handle)
  (ffi:ao_is_at_second_async (ao-handle-async-player handle))
  )
  
(define (ao-music-duration handle)
  (ffi:ao_music_duration_async (ao-handle-async-player handle))
  )

(define (ao-bufsize-async handle)
  (ffi:ao_bufsize_async (ao-handle-async-player handle))
  )

(define (ao-clear-async handle)
  (ffi:ao_clear_async (ao-handle-async-player handle))
  )