Prefetching

private/player.rkt

@@ -70,6 +70,7 @@
    [closed? #:mutable]
    state-lock
    command-lock
+   local-music-indexes
    dlna-port)
   #:transparent)
 
@@ -226,6 +227,14 @@
    value
    (λ ()
      (when (eq? handle (player-backend value))
+       (let* ((music-id (hash-ref full-state 'at-music-id #f))
+              (audible-index
+               (and (number? music-id)
+                    (hash-ref (player-local-music-indexes value)
+                              music-id
+                              #f))))
+         (when (exact-nonnegative-integer? audible-index)
+           (set-player-current-index! value audible-index)))
        (set-player-state! value (normalize-state state))
        (set-player-position!
         value
@@ -248,7 +257,14 @@
         ((exn:fail?
           (λ (exception)
             (set-error! value (exn-message exception)))))
-      (player-command! value "next" (hasheq)))))
+      (call-with-semaphore
+       (player-command-lock value)
+       (λ ()
+         (let ((index (next-index value 1)))
+           ;; Queue immediately at decoder EOF, but keep the old track selected
+           ;; until libao reports the new music id as actually audible.
+           (when index
+             (play-index! value index #t))))))))
 
 (define (make-local-backend value)
   (let ((backend
@@ -351,7 +367,7 @@
   (and (exact-nonnegative-integer? index)
        (< index (length (player-tracks value)))))
 
-(define (play-index! value index)
+(define (play-index! value index [defer-current-index? #f])
   (unless (valid-track-index? value index)
     (raise-arguments-error
      'player-command!
@@ -363,20 +379,26 @@
     (with-state-lock
      value
      (λ ()
-       (set-player-current-index! value index)
-       (set-player-state! value 'starting)
-       (set-player-position! value 0)
-       (set-player-duration! value (track-duration item))))
+       (unless defer-current-index?
+         (set-player-current-index! value index)
+         (set-player-state! value 'starting)
+         (set-player-position! value 0)
+         (set-player-duration! value (track-duration item)))))
     (cond
       ((eq? kind 'local)
-       (audio-play! backend (track-file item)))
+       (let ((music-id (audio-play! backend (track-file item))))
+         (with-state-lock
+          value
+          (λ ()
+            (hash-set! (player-local-music-indexes value)
+                       music-id
+                       index)))))
       ((eq? kind 'agent)
        (let* ((token (fresh-media-token))
               (data (agent-track-data item index token))
               (following-index (next-index value 1))
               (following-item
                (and following-index
-                    (not (= following-index index))
                     (list-ref (player-tracks value) following-index)))
               (following-token
                (and following-item (fresh-media-token)))
@@ -1027,6 +1049,7 @@
             #f
             (make-semaphore 1)
             (make-semaphore 1)
+            (make-hash)
             dlna-port)))
 
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