mp3.lisp

(in-package #:org.shirakumo.fraf.soloud)

(defclass mp3-source (virtual-source)
  ((file :initform NIL :accessor file)))

(defmethod load-file ((source mp3-source) file)
  (let ((file (cl-mpg123:make-file
               file
               :buffer-size (* 4 1024)
               :accepted-format (list (round (base-samplerate source)) :stereo :float))))
    (cl-mpg123:connect file)
    (cl-mpg123:scan file)
    (setf (channels source) 2)
    (setf (file source) file)))

(defmethod get-audio ((source mp3-source) dst samples)
  (let* ((bytes (* samples 4 2))
         (src (cl-mpg123:buffer (file source)))
         (read (cl-mpg123:read-directly (file source) src bytes))
         (read-samples (/ read 4 2)))
    ;; SoLoud wants L{n}R{n}, MPG123 gives (LR){n}. Need to re-encode.
    (loop for i from 0 below read-samples
          for k = (* i 2)
          do (setf (cffi:mem-aref dst :float i)             (cffi:mem-aref src :float k))
             (setf (cffi:mem-aref dst :float (+ samples i)) (cffi:mem-aref src :float (1+ k))))
    (when (< read bytes)
      (handler-bind ((error #'invoke-debugger))
        (cond ((looping-p source)
               (rewind source)
               (get-audio source (cffi:inc-pointer dst read) (/ (- bytes read) 4 2)))
              (T
               (loop for i from read-samples below samples
                     do (setf (cffi:mem-aref dst :float i) 0.0s0))))))))

(defmethod has-ended ((source mp3-source))
  (unless (looping-p source)
    (<= (cl-mpg123:sample-count (file source))
        (cl-mpg123:sample-position (file source)))))

(defmethod seek-to ((source mp3-source) time scratch size)
  ;; I don't actually know what these arguments are.
  )

(defmethod rewind ((source mp3-source))
  (cl-mpg123:seek (file source) 0)
  0)

(defmethod get-info ((source mp3-source) info-key)
  0.0)