initial import from racket-sound -> racket-audio

2026-05-04 12:07:45 +02:00
parent f500f1711b
commit 87980f508a
28 changed files with 6282 additions and 16 deletions
@@ -0,0 +1,157 @@
+(module mp3-decoder racket/base
+
+  (require ffi/unsafe
+           "libmpg123-ffi.rkt"
+           "private/utils.rkt"
+           (prefix-in fin: finalizer)
+           )
+
+  (provide mp3-open
+           mp3-valid?
+           mp3-read
+           mp3-stop
+           mp3-seek
+           )
+
+
+  (define-struct mp3-handle
+    (if cb-info cb-audio
+        (stop #:mutable)
+        (seek #:mutable)
+        (reading #:mutable)
+        (format #:mutable)
+        )
+    #:transparent
+    )
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Functions to do the good stuff  
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+  (define (mp3-valid? mp3-file)
+    #t)
+
+  (define audio-type 'mp3)
+
+  (define last-rate 44200)    ; An assumption for if we've got nothing
+  (define last-channels 2)    ; An assumption for if we've got nothing
+  (define last-bits 16)       ; An assumption for if we've got nothing
+
+  (define (correct-format-hash h)
+    (let ((rate (hash-ref h 'sample-rate #f)))
+      (when (eq? rate #f)
+        (hash-set! h 'sample-rate last-rate)))
+    (let ((channels (hash-ref h 'channels #f)))
+      (when (eq? channels #f)
+        (hash-set! h 'channels last-channels)))
+    (let ((bits (hash-ref h 'bits-per-sample #f)))
+      (when (eq? bits #f)
+        (hash-set! h 'bits-per-sample last-bits)))
+    (let ((total-samples (hash-ref h 'total-samples #f)))
+      (when (eq? total-samples #f)
+        (hash-set! h 'total-samples 0)
+        (hash-set! h 'duration 0)))
+    )
+
+  (define (report-format handle current-pcm-pos)
+    (dbg-sound "Reporting format at pcm-pos: ~a" current-pcm-pos)
+    (let ((h (mp3-handle-format handle)))
+      (set! last-rate (hash-ref h 'sample-rate))
+      (set! last-channels (hash-ref h 'channels))
+      (set! last-bits (hash-ref h 'bits-per-sample)))
+    ((mp3-handle-cb-info handle) (mp3-handle-format handle)))
+
+  (define (give-audio handle info pos buffer size)
+    (let ((h (mp3-handle-format handle)))
+      (correct-format-hash h)
+      (hash-set! h 'sample pos)
+      (let ((sample-rate (hash-ref h 'sample-rate last-rate)))
+        (hash-set! h 'current-time (exact->inexact (/ pos sample-rate))))
+      ((mp3-handle-cb-audio handle) h buffer size)))
+
+  (define (mp3-open mp3-file* cb-stream-info cb-audio)
+    (let ((mp3-file (if (path? mp3-file*) (path->string mp3-file*) mp3-file*)))
+      (if (file-exists? mp3-file)
+          (let ((handler (mpg123-ffi-decoder-handler)))
+            (handler 'new)
+            (handler 'init mp3-file)
+            (let ((h (make-mp3-handle handler
+                                      cb-stream-info
+                                      cb-audio
+                                      #f
+                                      #f
+                                      #f
+                                      (make-hash)
+                                      )))
+              h))
+          #f)))
+
+
+  (define (handle-format handle pcm-pos rate channels sample-bits sample-bytes pcm-length)
+    (let ((f (make-hash)))
+      (hash-set! f 'duration (exact->inexact (/ pcm-length rate)))
+      (hash-set! f 'sample-rate rate)
+      (hash-set! f 'channels channels)
+      (hash-set! f 'bits-per-sample sample-bits)
+      (hash-set! f 'bytes-per-sample sample-bytes)
+      (hash-set! f 'total-samples pcm-length)
+      (set-mp3-handle-format! handle f)
+      )
+    (report-format handle pcm-pos)
+    )
+
+  (define (mp3-read handle)
+    (let* ((ffi-handler (mp3-handle-if handle))
+           (cb-info (mp3-handle-cb-info handle))
+           (cb-audio (mp3-handle-cb-audio handle))
+           )
+      (set-mp3-handle-reading! handle #t)
+      (let loop ()
+        (if (eq? (mp3-handle-stop handle) #t)
+            (begin
+              (dbg-sound "Stopping mp3 decoding")
+              (set-mp3-handle-reading! handle #f)
+              'stopped-reading
+              )
+            (begin
+              (unless (eq? (mp3-handle-seek handle) #f)
+                (dbg-sound "Seeking to ~a" (mp3-handle-seek handle))
+                (ffi-handler 'seek (mp3-handle-seek handle))
+                (set-mp3-handle-seek! handle #f))
+              (ffi-handler 'read
+                           (λ (info pos buffer size)
+                             (if (eq? info 'done)
+                                 (set-mp3-handle-stop! handle #t)
+                                 (give-audio handle info pos buffer size)
+                                 ))
+                           (λ (pcm-pos rate channels sample-bits sample-bytes pcm-length)
+                             (handle-format handle pcm-pos rate channels sample-bits sample-bytes pcm-length))
+                           )
+              (loop)
+              )
+            ))
+      (ffi-handler 'close)
+      (ffi-handler 'delete)
+      )
+    )
+
+  (define (mp3-seek handle percentage)
+    (let ((fmt (mp3-handle-format handle)))
+      (let ((total-samples (hash-ref fmt 'total-samples 0)))
+        (unless (or
+                 (eq? total-samples #f)
+                 (= total-samples -1))
+          (let ((sample (inexact->exact (round (* (exact->inexact (/ percentage 100.0)) total-samples)))))
+            (set-mp3-handle-seek! handle sample))
+          )
+        )
+      )
+    )
+
+  (define (mp3-stop handle)
+    (set-mp3-handle-stop! handle #t)
+    (while (mp3-handle-reading handle)
+           (sleep 0.01))
+    )
+                         
+  ); end of module