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-ffi.rkt

@@ -16,8 +16,17 @@
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
   (define (ok? r)
-    (not (= r 0)))
+    (> r 0))
+  
+  (define (decode-ok? r)
+    (= r 1))
 
+  (define (decode-eof? r)
+    (= r 0))
+
+  (define (decode-error? r)
+    (< r 0))
+  
   (define (filename->string filename)
     (cond
       [(path? filename) (path->string filename)]
@@ -149,18 +158,45 @@
         (reset!)
         #t))
 
+    #|
     (define (read cb format-cb)
       (when (= current-pcm-pos 0)
         (ffmpeg-format format-cb))
-      (if (ok? (fmpg-decode-next! fh))
-          (let-values ([(buffer size) (copy-current-buffer fh)])
-            (cond
-              [(or (eq? buffer #f) (<= size 0)) (read cb format-cb)]
-              [else
-               (let ((pcm-pos (fmpg-buffer-start-sample fh)))
-                 (set! current-pcm-pos (fmpg-buffer-end-sample fh))
-                 (cb 'data pcm-pos buffer size))]))
-          (cb 'done -1 #f 0))
+      (let ((dec-val (fmpg-decode-next! fh)))
+        (unless (ok? dec-val)
+          (err-sound "return value of fmpg-decode-next = ~a" dec-val))
+        (if (ok? dec-val)
+            (let-values ([(buffer size) (copy-current-buffer fh)])
+              (cond
+                [(or (eq? buffer #f) (<= size 0)) (read cb format-cb)]
+                [else
+                 (let ((pcm-pos (fmpg-buffer-start-sample fh)))
+                   (set! current-pcm-pos (fmpg-buffer-end-sample fh))
+                   (cb 'data pcm-pos buffer size))]))
+            (cb 'done -1 #f 0))
+        #t))
+    |#
+    (define (read cb format-cb)
+      (when (= current-pcm-pos 0)
+        (ffmpeg-format format-cb))
+      (let ((dec-val (fmpg-decode-next! fh)))
+        (cond
+          [(decode-ok? dec-val)
+           (let-values ([(buffer size) (copy-current-buffer fh)])
+             (cond
+               [(or (eq? buffer #f) (<= size 0))
+                (read cb format-cb)]
+               [else
+                (let ((pcm-pos (fmpg-buffer-start-sample fh)))
+                  (set! current-pcm-pos (fmpg-buffer-end-sample fh))
+                  (cb 'data pcm-pos buffer size))]))]
+
+          [(decode-eof? dec-val)
+           (cb 'done -1 #f 0)]
+
+          [else
+           (err-sound "fmpg-decode-next failed: ~a" dec-val)
+           (cb 'done -1 #f 0)]))
       #t)
 
     (define (seek pcm-pos)