97 lines
4.4 KiB
Common Lisp
97 lines
4.4 KiB
Common Lisp
(in-package #:cl-streamer)
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(defclass mp3-encoder ()
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((lame :initform nil :accessor encoder-lame)
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(sample-rate :initarg :sample-rate :accessor encoder-sample-rate :initform 44100)
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(channels :initarg :channels :accessor encoder-channels :initform 2)
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(bitrate :initarg :bitrate :accessor encoder-bitrate :initform 128)
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(quality :initarg :quality :accessor encoder-quality :initform 5)
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(mp3-buffer :initform nil :accessor encoder-mp3-buffer)
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(mp3-buffer-size :initform (* 1024 8) :accessor encoder-mp3-buffer-size)))
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(defun make-mp3-encoder (&key (sample-rate 44100) (channels 2) (bitrate 128) (quality 5))
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"Create an MP3 encoder with the specified parameters.
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QUALITY: 0=best/slowest, 9=worst/fastest. 5 is good default."
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(let ((encoder (make-instance 'mp3-encoder
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:sample-rate sample-rate
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:channels channels
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:bitrate bitrate
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:quality quality)))
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(initialize-encoder encoder)
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encoder))
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(defun initialize-encoder (encoder)
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"Initialize the LAME encoder with current settings."
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(let ((lame (lame-init)))
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(when (cffi:null-pointer-p lame)
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(error 'encoding-error :format :mp3 :message "Failed to initialize LAME"))
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(setf (encoder-lame encoder) lame)
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(lame-set-in-samplerate lame (encoder-sample-rate encoder))
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(lame-set-out-samplerate lame (encoder-sample-rate encoder))
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(lame-set-num-channels lame (encoder-channels encoder))
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(lame-set-mode lame (if (= (encoder-channels encoder) 1) :mono :joint-stereo))
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(lame-set-brate lame (encoder-bitrate encoder))
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(lame-set-quality lame (encoder-quality encoder))
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(lame-set-vbr lame :vbr-off)
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(let ((result (lame-init-params lame)))
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(when (< result 0)
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(lame-close lame)
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(error 'encoding-error :format :mp3
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:message (format nil "LAME init-params failed: ~A" result))))
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(setf (encoder-mp3-buffer encoder)
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(cffi:foreign-alloc :unsigned-char :count (encoder-mp3-buffer-size encoder)))
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(log:info "MP3 encoder initialized: ~Akbps, ~AHz, ~A channels"
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(encoder-bitrate encoder)
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(encoder-sample-rate encoder)
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(encoder-channels encoder))
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encoder))
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(defun close-encoder (encoder)
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"Close the encoder and free resources."
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(when (encoder-lame encoder)
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(lame-close (encoder-lame encoder))
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(setf (encoder-lame encoder) nil))
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(when (encoder-mp3-buffer encoder)
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(cffi:foreign-free (encoder-mp3-buffer encoder))
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(setf (encoder-mp3-buffer encoder) nil)))
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(defun encode-pcm-interleaved (encoder pcm-samples num-samples)
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"Encode interleaved PCM samples (16-bit signed) to MP3.
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PCM-SAMPLES should be a (simple-array (signed-byte 16) (*)).
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Returns a byte vector of MP3 data."
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(let* ((lame (encoder-lame encoder))
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(mp3-buf (encoder-mp3-buffer encoder))
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(mp3-buf-size (encoder-mp3-buffer-size encoder)))
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(cffi:with-pointer-to-vector-data (pcm-ptr pcm-samples)
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(let ((bytes-written (lame-encode-buffer-interleaved
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lame pcm-ptr num-samples mp3-buf mp3-buf-size)))
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(cond
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((< bytes-written 0)
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(error 'encoding-error :format :mp3
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:message (format nil "Encode failed: ~A" bytes-written)))
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((= bytes-written 0)
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(make-array 0 :element-type '(unsigned-byte 8)))
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(t
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(let ((result (make-array bytes-written :element-type '(unsigned-byte 8))))
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(loop for i below bytes-written
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do (setf (aref result i) (cffi:mem-aref mp3-buf :unsigned-char i)))
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result)))))))
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(defun encode-flush (encoder)
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"Flush any remaining MP3 data from the encoder.
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Call this when done encoding to get final frames."
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(let* ((lame (encoder-lame encoder))
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(mp3-buf (encoder-mp3-buffer encoder))
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(mp3-buf-size (encoder-mp3-buffer-size encoder)))
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(let ((bytes-written (lame-encode-flush lame mp3-buf mp3-buf-size)))
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(if (> bytes-written 0)
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(let ((result (make-array bytes-written :element-type '(unsigned-byte 8))))
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(loop for i below bytes-written
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do (setf (aref result i) (cffi:mem-aref mp3-buf :unsigned-char i)))
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result)
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(make-array 0 :element-type '(unsigned-byte 8))))))
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(defun lame-version ()
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"Return the LAME library version string."
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(get-lame-version))
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