audio decoding

audio-decoder.rkt

@@ -24,7 +24,7 @@
   ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   
   (define-struct audio-reader
-    (exts open reader seeker stopper))
+    (exts valid? open reader seeker stopper))
 
   ;; audiotype, audio-reader
   (define audio-readers (make-hash))
@@ -32,6 +32,7 @@
   (hash-set! audio-readers
              'flac
              (make-audio-reader '("flac")
+                                flac-valid?
                                 flac-open
                                 flac-read
                                 flac-seek
@@ -84,7 +85,40 @@
     (-> (or/c string? path?) boolean?)
     (let ((f (build-path file)))
       (let ((e (format "~a" (path-get-extension f))))
-        (audio-valid-ext? e))))
+        (if (audio-valid-ext? e)
+            (let ((reader (find-reader file)))
+              (if (eq? reader #f)
+                  #f
+                  (audio-reader-valid? file)))
+            #f))))
+
+  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+  ; cb-stream-info will be called with
+  ;    - audio-type: symbol?
+  ;    - handle: audio-handle?
+  ;    - meta: hash?
+  ;    Meta information must at least contain:
+  ;        ('duration . seconds) - duration of the audio in seconds (or fractions): double
+  ;        ('bits-per-sample . integer) - number of audio bits per sample
+  ;        ('channels . integer) - number of audio channels
+  ;        ('sample-rate . integer) - number of samples per second per channel
+  ;        ('total-samples . integer) - total number of samples of the audio
+  ;
+  ; cb-audio will be called with
+  ;    - audio-type: symbol?
+  ;    - handle: audio-handle?
+  ;    - buf-info: hash?
+  ;    - buffer: cpointer?     - contains data to be fed to ao - must be owned / released by the driver
+  ;                              the ao-async backend will copy the data
+  ;    - buf-size: integer?    - contains the size of the data
+  ;    buf-info must at least contain:
+  ;        ('duration . seconds) - duration of the audio in seconds (or fractions): double
+  ;        ('bits-per-sample . integer) - number of audio bits per sample
+  ;        ('channels . integer) - number of audio channels
+  ;        ('sample-rate . integer) - number of samples per second per channel
+  ;        ('total-samples . integer) - total number of samples of the audio
+  ;        (sample . integer) - the current sample the audio buffer applies to.
+  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
   (define/contract (audio-open audio-file cb-stream-info cb-audio)
     (-> (or/c string? path?) procedure? procedure? audio-handle?)

flac-decoder.rkt

@@ -6,6 +6,7 @@
            "private/utils.rkt")
 
   (provide flac-open
+           flac-valid?
            flac-read
            flac-read-meta
            flac-stream-state
@@ -20,6 +21,9 @@
 ;; Functions to do the good stuff  
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
+  (define (flac-valid? flac-file*)
+    #t)
+
   (define (flac-open flac-file* cb-stream-info cb-audio)
     (let ((flac-file (if (path? flac-file*) (path->string flac-file*) flac-file*)))
       (if (file-exists? flac-file)

play-test.rkt

@@ -36,6 +36,7 @@
          (bytes-per-sample-all-channels (* channels bytes-per-sample))
          (duration (hash-ref buf-info 'duration))
          )
+    (displayln buf-info)
     (when (eq? ao-h #f)
       (set! ao-h (ao-open-live bits-per-sample rate channels 'big-endian)))
     ;(displayln 'ao-play)