much work on the player and hunting for a bug, which first seemed to be in ffmpeg-decoder, but eventually was found in a race condition in audio-placed-player.rkt and an allocation problem in libao-async-ffi-racket.rkt

libao-async-ffi-racket.rkt

@@ -225,12 +225,13 @@
   )
 
 
-(define (needed-bytes h)
+(define (needed-bytes h elem-buflen)
   (let ((req-bytes (/ (ao-handle-dev-bits-per-sample h) 8))
         (rate-s (ao-handle-dev-rate h))
         (channels (ao-handle-dev-channels h))
         )
-    (/ (* req-bytes rate-s channels ao-buf-ms) 1000)
+    (let ((needed-for-ao (/ (* req-bytes rate-s channels ao-buf-ms) 1000)))
+      (max needed-for-ao elem-buflen))
     )
   )
 
@@ -256,7 +257,7 @@
             (begin
               (set-ao-handle-current-elem! h elem)
               (set! cb elem)
-              (let* ((ns (needed-bytes h))
+              (let* ((ns (needed-bytes h (queue-elem-buflen elem)))
                      (new-buf (alloc-buf h ns)))
                 (m-memcpy new-buf (queue-elem-buf cb) (queue-elem-buflen cb))
                 (reuse-buf h (queue-elem-buf cb))