217 lines
9.9 KiB
Racket
217 lines
9.9 KiB
Racket
(module opus-encoder racket/base
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(require ffi/unsafe
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"private/utils.rkt")
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(provide opus-encoder-available?
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opus-encoder-default-settings
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opus-encoder-prepare-settings
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opus-encoder-open
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opus-encoder-write
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opus-encoder-finish)
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;; libopusenc handles the Ogg container, OpusHead and OpusTags. The Racket
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;; side feeds interleaved floating-point PCM to ope_encoder_write_float().
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;; The input rate passed to ope_encoder_create_file is the source PCM rate;
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;; libopusenc performs the required Opus resampling internally.
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;; Load libogg and libopus explicitly before libopusenc. This matters on
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;; Windows, where libopusenc.dll may not reliably find its dependent DLLs
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;; unless they have already been resolved through the same search path.
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(define libogg
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(get-lib (case (system-type 'os)
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[(windows) '("ogg")]
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[else '("ogg" "libogg")])
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'(#f)))
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(define libopus
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(get-lib (case (system-type 'os)
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[(windows) '("opus")]
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[else '("opus" "libopus")])
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'(#f)))
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(define libopusenc
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(get-lib (case (system-type 'os)
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[(windows) '("libopusenc")]
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[else '("opusenc" "libopusenc")])
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'(#f)))
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(define _OggOpusComments (_cpointer/null 'ogg-opus-comments))
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(define _OggOpusEnc (_cpointer/null 'ogg-opus-enc))
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(define (ffi-proc name type)
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(and libopusenc
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(with-handlers ([exn:fail? (lambda (_) #f)])
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(get-ffi-obj name libopusenc type))))
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(define ope_comments_create (ffi-proc "ope_comments_create" (_fun -> _OggOpusComments)))
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(define ope_comments_destroy (ffi-proc "ope_comments_destroy" (_fun _OggOpusComments -> _void)))
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(define ope_comments_add (ffi-proc "ope_comments_add" (_fun _OggOpusComments _string/utf-8 _string/utf-8 -> _int)))
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(define ope_comments_add_picture_from_memory
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(ffi-proc "ope_comments_add_picture_from_memory" (_fun _OggOpusComments _bytes _size _int _string/utf-8 -> _int)))
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(define ope_encoder_create_file
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(ffi-proc "ope_encoder_create_file"
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(_fun _string/utf-8 _OggOpusComments _int32 _int _int (err : (_ptr o _int))
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-> (enc : _OggOpusEnc)
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-> (values enc err))))
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(define ope_encoder_write_float (ffi-proc "ope_encoder_write_float" (_fun _OggOpusEnc _pointer _int -> _int)))
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(define ope_encoder_drain (ffi-proc "ope_encoder_drain" (_fun _OggOpusEnc -> _int)))
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(define ope_encoder_destroy (ffi-proc "ope_encoder_destroy" (_fun _OggOpusEnc -> _void)))
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(define ope_strerror (ffi-proc "ope_strerror" (_fun _int -> _string/utf-8)))
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(define ope_encoder_ctl/int (ffi-proc "ope_encoder_ctl" (_fun #:varargs-after 2 _OggOpusEnc _int _int -> _int)))
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(define OPUS_SET_BITRATE_REQUEST 4002)
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(define OPUS_SET_VBR_REQUEST 4006)
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(define OPUS_SET_COMPLEXITY_REQUEST 4010)
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(define OPUS_SET_VBR_CONSTRAINT_REQUEST 4020)
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(define OPUS_SET_SIGNAL_REQUEST 4024)
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(define OPUS_SET_LSB_DEPTH_REQUEST 4036)
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(define OPE_SET_COMMENT_PADDING_REQUEST 14004)
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(define OPUS_AUTO -1000)
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(define OPUS_SIGNAL_VOICE 3001)
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(define OPUS_SIGNAL_MUSIC 3002)
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(define (opus-encoder-available?)
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(and libogg libopus libopusenc ope_comments_create ope_comments_destroy ope_encoder_create_file
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ope_encoder_write_float ope_encoder_drain ope_encoder_destroy ope_strerror #t))
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(define-struct opus-encoder-handle (enc comments settings format file) #:transparent)
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(define (hash-ref/default h k default)
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(if (hash-has-key? h k) (hash-ref h k) default))
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(define (copy-hash h)
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(let ((out (make-hash)))
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(for-each (lambda (k) (hash-set! out k (hash-ref h k))) (hash-keys h))
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out))
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(define (hash-merge base override)
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(let ((out (copy-hash base)))
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(when (hash? override)
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(for-each (lambda (k) (hash-set! out k (hash-ref override k))) (hash-keys override)))
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out))
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(define (opus-error-message code)
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(if ope_strerror (ope_strerror code) (format "libopusenc error ~a" code)))
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(define (check-ope who r)
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(when (negative? r) (error who "~a" (opus-error-message r)))
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r)
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(define (opus-encoder-default-settings)
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(make-hash '((bitrate . 160000)
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(vbr? . #t)
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(constrained-vbr? . #f)
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(complexity . 10)
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(comment-padding . 512))))
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(define (signal->int v)
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(cond [(or (eq? v 'auto) (eq? v #f)) OPUS_AUTO]
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[(eq? v 'voice) OPUS_SIGNAL_VOICE]
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[(eq? v 'music) OPUS_SIGNAL_MUSIC]
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[else (raise-argument-error 'opus-signal "(or/c 'auto 'voice 'music)" v)]))
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(define (source-value v source)
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(if (eq? v 'source) source v))
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(define (opus-encoder-prepare-settings settings format)
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(let* ((h (hash-merge (opus-encoder-default-settings) settings))
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(rate (source-value (hash-ref/default h 'sample-rate (hash-ref format 'sample-rate))
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(hash-ref format 'sample-rate)))
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(channels (source-value (hash-ref/default h 'channels (hash-ref format 'channels))
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(hash-ref format 'channels))))
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;; Do not apply the low-level libopus sample-rate restriction here.
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;; libopusenc accepts the input rate and performs the required resampling
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;; internally; 44100 Hz input is therefore valid.
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(when (> channels 2)
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(error 'opus-encoder-open "this first direct libopusenc backend only supports mono/stereo input; got ~a channels" channels))
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(hash-set! h 'sample-rate rate)
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(hash-set! h 'channels channels)
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(hash-set! h 'family 0)
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h))
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(define (apply-ctl! enc request value who)
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(when ope_encoder_ctl/int
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(check-ope who (ope_encoder_ctl/int enc request value))))
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(define (apply-settings! enc settings)
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(apply-ctl! enc OPUS_SET_BITRATE_REQUEST (hash-ref settings 'bitrate) 'opus-bitrate)
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(apply-ctl! enc OPUS_SET_VBR_REQUEST (if (hash-ref/default settings 'vbr? #t) 1 0) 'opus-vbr)
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(apply-ctl! enc OPUS_SET_VBR_CONSTRAINT_REQUEST (if (hash-ref/default settings 'constrained-vbr? #f) 1 0) 'opus-constrained-vbr)
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(apply-ctl! enc OPUS_SET_COMPLEXITY_REQUEST (hash-ref/default settings 'complexity 10) 'opus-complexity)
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(apply-ctl! enc OPE_SET_COMMENT_PADDING_REQUEST (hash-ref/default settings 'comment-padding 512) 'opus-comment-padding)
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(when (hash-has-key? settings 'signal)
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(apply-ctl! enc OPUS_SET_SIGNAL_REQUEST (signal->int (hash-ref settings 'signal)) 'opus-signal))
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(when (hash-has-key? settings 'lsb-depth)
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(apply-ctl! enc OPUS_SET_LSB_DEPTH_REQUEST (hash-ref settings 'lsb-depth) 'opus-lsb-depth)))
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(define (add-comments! comments settings)
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(when (hash-has-key? settings 'comments)
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(let ((ch (hash-ref settings 'comments)))
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(when (hash? ch)
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(for-each (lambda (k)
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(let ((v (hash-ref ch k)))
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(when (string? v)
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(check-ope 'opus-comment (ope_comments_add comments (string-upcase (symbol->string k)) v)))))
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(hash-keys ch))))))
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(define (opus-encoder-open output-file settings format)
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(unless (opus-encoder-available?)
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(error 'opus-encoder-open "libopusenc or one of its dependent libraries (ogg/opus) could not be loaded"))
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(let* ((file (if (path? output-file) (path->string output-file) output-file))
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(resolved (opus-encoder-prepare-settings settings format))
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(comments (ope_comments_create)))
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(add-comments! comments resolved)
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(let-values (((enc err) (ope_encoder_create_file file comments
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(hash-ref resolved 'sample-rate)
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(hash-ref resolved 'channels)
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(hash-ref resolved 'family))))
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(unless enc (error 'opus-encoder-open "could not create Opus file ~a: ~a" file (opus-error-message err)))
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(apply-settings! enc resolved)
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(make-opus-encoder-handle enc comments resolved format file))))
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(define (native-signed-ref bs start bytes)
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;; Racket's integer-bytes->integer only supports 1, 2, 4 and 8 bytes.
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;; The FLAC decoder legitimately produces 24-bit PCM as three bytes per
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;; sample, so use the package helper that handles that case.
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(int-bytes->integer bs #t (system-big-endian?) start (+ start bytes)))
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(define (sample->float sample in-bits)
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(let* ((scale (expt 2 (sub1 in-bits)))
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(v (/ sample scale)))
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(cond [(< v -1.0) -1.0]
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[(> v 1.0) 1.0]
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[else (exact->inexact v)])))
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(define (pcm-bytes->float-pointer buffer size in-bits)
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(let* ((in-bytes (quotient in-bits 8))
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(sample-count (quotient size in-bytes))
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(ptr (malloc _float sample-count 'atomic-interior)))
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(for ([i (in-range sample-count)])
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(let* ((in-off (* i in-bytes))
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(sample (native-signed-ref buffer in-off in-bytes)))
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(ptr-set! ptr _float i (sample->float sample in-bits))))
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(values ptr sample-count)))
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(define (opus-encoder-write handle buf-info buffer buf-len)
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(let* ((settings (opus-encoder-handle-settings handle))
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(channels (hash-ref settings 'channels))
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(in-bits (hash-ref/default buf-info 'pcm-bits-per-sample
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(hash-ref/default buf-info 'bits-per-sample 16))))
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(let-values (((pcm sample-count) (pcm-bytes->float-pointer buffer buf-len in-bits)))
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(let ((frames (quotient sample-count channels)))
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(check-ope 'opus-encoder-write
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(ope_encoder_write_float (opus-encoder-handle-enc handle) pcm frames))
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frames))))
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(define (opus-encoder-finish handle)
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(dynamic-wind
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void
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(lambda () (check-ope 'opus-encoder-finish (ope_encoder_drain (opus-encoder-handle-enc handle))))
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(lambda ()
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(ope_encoder_destroy (opus-encoder-handle-enc handle))
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(ope_comments_destroy (opus-encoder-handle-comments handle)))))
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) ; end of module
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