more defensive constructs with early-return & let-assert

libao-async-ffi-racket.rkt

@@ -33,6 +33,8 @@
          ao_sample_queue_len
          make-buffer-info
          make-BufferInfo_t
+         ao-playback-buf-ms
+         ao-set-playback-buf-ms!
          )
 
 ;; -------------------------------------------------------------------------
@@ -194,7 +196,13 @@
 ;; Playback buffer to send to libao in milliseconds
 ;; -------------------------------------------------------------------------
 
-(define ao-buf-ms 1000)  ;; Playback buffer of 0.25s
+(define ao-buf-ms 350)  ;; Playback buffer of 0.35s
+
+(define (ao-playback-buf-ms)
+  ao-buf-ms)
+
+(define (ao-set-playback-buf-ms! ms)
+  (set! ao-buf-ms ms))
 
 ;; -------------------------------------------------------------------------
 ;; Sample queue handling
@@ -272,7 +280,7 @@
                   (reuse-buf h (queue-elem-buf elem))
                   (when (= (ao-handle-bytes-left h) 0)
                     (async-channel-put (ao-handle-queue h) cb)
-                    (set-ao-handle-in-queue! h (+ ao-handle-in-queue h) 1)
+                    (set-ao-handle-in-queue! h (+ (ao-handle-in-queue h) 1))
                     (set-ao-handle-current-elem! h #f))
                   )
                 )
@@ -423,8 +431,8 @@
 
 
 (define (planar-to-interleaved h in-buf info)
-  ;; mem: bytes
-  ;; result: (list bytes output-size)
+  ;; in-buf: mem
+  ;; result: mem
 
   (let* ([in-bytes   (mem-bytes in-buf)]
          [buf-size   (mem-size in-buf)]
@@ -456,7 +464,7 @@
                              bytes)])
             (bytes-copy! out-bytes out-pos in-bytes in-pos (+ in-pos bytes)))))
 
-      out out-size)))
+      out)))
 
 ;;; requested bits to device bits