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

ffmpeg-decoder.rkt

@@ -128,7 +128,9 @@
               (ffi-handler 'read
                            (lambda (info pos buffer size)
                              (if (eq? info 'done)
-                                 (set-ffmpeg-handle-stop! handle #t)
+                                 (begin
+                                   (dbg-sound "ffmpeg read: ~a ~a ~a" info pos size)
+                                   (set-ffmpeg-handle-stop! handle #t))
                                  (give-audio handle info pos buffer size)))
                            (lambda (pcm-pos rate channels sample-bits sample-bytes pcm-length)
                              (handle-format handle pcm-pos rate channels sample-bits sample-bytes pcm-length)))
@@ -138,6 +140,7 @@
       (ffi-handler 'delete)))
 
   (define (ffmpeg-seek handle percentage)
+    (dbg-sound "ffmpeg-seek ~a" percentage)
     (let ((fmt (ffmpeg-handle-format handle)))
       (let ((total-samples (hash-ref fmt 'total-samples 0)))
         (unless (or
@@ -149,6 +152,7 @@
             (set-ffmpeg-handle-seek! handle sample))))))
 
   (define (ffmpeg-stop handle)
+    (dbg-sound "ffmpeg-stop called")
     (set-ffmpeg-handle-stop! handle #t)
     (while (ffmpeg-handle-reading handle)
            (sleep 0.01)))