Audio Encoder laag.

2026-06-08 10:27:05 +02:00
parent 696ef1b978
commit 444d62edac
7 changed files with 836 additions and 1 deletions
@@ -6,6 +6,7 @@
         )

 (provide flac-ffi-decoder-handler
+         flac-ffi-encoder-handler
         _FLAC__StreamMetadata
         FLAC__StreamMetadata-type
         flac-ffi-meta
@@ -371,6 +372,7 @@
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

 (define _FLAC__StreamDecoder-pointer (_cpointer 'flac-streamdecoder))
+(define _FLAC__StreamEncoder-pointer (_cpointer 'flac-streamencoder))
 (define _FLAC__Data-pointer (_cpointer/null 'flac-client-data))
 ;(define _FLAC__StreamMetadata-pointer (_cpointer/null 'flac-stream-metadata))

@@ -639,5 +641,164 @@
      ))
  )

+
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Direct FLAC encoder interface
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(define FLAC__StreamEncoderInitStatus-ok 0)
+
+(define _FLAC__StreamEncoderProgressCallback _pointer)
+
+(define-libflac FLAC__stream_encoder_new
+  (_fun -> _FLAC__StreamEncoder-pointer))
+
+(define-libflac FLAC__stream_encoder_delete
+  (_fun _FLAC__StreamEncoder-pointer -> _void))
+
+(define-libflac FLAC__stream_encoder_finish
+  (_fun _FLAC__StreamEncoder-pointer -> FLAC__bool))
+
+(define-libflac FLAC__stream_encoder_get_state
+  (_fun _FLAC__StreamEncoder-pointer -> _int))
+
+(define-libflac FLAC__stream_encoder_set_verify
+  (_fun _FLAC__StreamEncoder-pointer FLAC__bool -> FLAC__bool))
+
+(define-libflac FLAC__stream_encoder_set_streamable_subset
+  (_fun _FLAC__StreamEncoder-pointer FLAC__bool -> FLAC__bool))
+
+(define-libflac FLAC__stream_encoder_set_channels
+  (_fun _FLAC__StreamEncoder-pointer _uint32_t -> FLAC__bool))
+
+(define-libflac FLAC__stream_encoder_set_bits_per_sample
+  (_fun _FLAC__StreamEncoder-pointer _uint32_t -> FLAC__bool))
+
+(define-libflac FLAC__stream_encoder_set_sample_rate
+  (_fun _FLAC__StreamEncoder-pointer _uint32_t -> FLAC__bool))
+
+(define-libflac FLAC__stream_encoder_set_compression_level
+  (_fun _FLAC__StreamEncoder-pointer _uint32_t -> FLAC__bool))
+
+(define-libflac FLAC__stream_encoder_set_blocksize
+  (_fun _FLAC__StreamEncoder-pointer _uint32_t -> FLAC__bool))
+
+(define-libflac FLAC__stream_encoder_set_total_samples_estimate
+  (_fun _FLAC__StreamEncoder-pointer FLAC__uint64 -> FLAC__bool))
+
+(define-libflac FLAC__stream_encoder_init_file
+  (_fun _FLAC__StreamEncoder-pointer
+        _string/utf-8
+        _FLAC__StreamEncoderProgressCallback
+        _FLAC__Data-pointer
+        -> _int))
+
+(define-libflac FLAC__stream_encoder_process_interleaved
+  (_fun _FLAC__StreamEncoder-pointer _pointer _uint32_t -> FLAC__bool))
+
+(define (hash-ref/default h k default)
+  (if (hash-has-key? h k) (hash-ref h k) default))
+
+(define (bool->flac-bool v) (if v 1 0))
+
+(define (native-signed-ref bs start bytes)
+  (integer-bytes->integer bs #t (system-big-endian?) start (+ start bytes)))
+
+(define (scale-sample sample in-bits out-bits)
+  (cond [(> in-bits out-bits) (arithmetic-shift sample (- out-bits in-bits))]
+        [(< in-bits out-bits) (arithmetic-shift sample (- out-bits in-bits))]
+        [else sample]))
+
+(define (pcm-bytes->flac-int32-pointer buffer size channels in-bits out-bits)
+  (let* ((in-bytes (quotient in-bits 8))
+         (sample-count (quotient size in-bytes))
+         (frame-count (quotient sample-count channels))
+         (ptr (malloc _int32 sample-count 'atomic-interior)))
+    (for ([i (in-range sample-count)])
+      (let* ((off (* i in-bytes))
+             (sample (native-signed-ref buffer off in-bytes)))
+        (ptr-set! ptr _int32 i (scale-sample sample in-bits out-bits))))
+    (values ptr frame-count)))
+
+(define (flac-ffi-encoder-handler)
+  (define enc #f)
+  (define flac-file #f)
+  (define settings #f)
+
+  (define (require-encoder who)
+    (when (eq? enc #f) (error who "FLAC encoder is not initialized")))
+
+  (define (new)
+    (if (eq? enc #f)
+        (begin (set! enc (FLAC__stream_encoder_new)) enc)
+        (error 'flac-ffi-encoder-handler "FLAC encoder already initialized")))
+
+  (define (configure h)
+    (require-encoder 'flac-encoder-configure)
+    (set! settings h)
+    (let ((channels (hash-ref h 'channels))
+          (sample-rate (hash-ref h 'sample-rate))
+          (bits (hash-ref h 'bits-per-sample))
+          (compression-level (hash-ref/default h 'compression-level 5))
+          (verify? (hash-ref/default h 'verify? #f))
+          (streamable-subset? (hash-ref/default h 'streamable-subset? (<= (hash-ref h 'bits-per-sample) 24)))
+          (blocksize (hash-ref/default h 'blocksize 0))
+          (total-samples (hash-ref/default h 'total-samples #f)))
+      (unless (FLAC__stream_encoder_set_channels enc channels) (error 'flac-encoder-configure "could not set channels"))
+      (unless (FLAC__stream_encoder_set_sample_rate enc sample-rate) (error 'flac-encoder-configure "could not set sample rate"))
+      (unless (FLAC__stream_encoder_set_bits_per_sample enc bits) (error 'flac-encoder-configure "could not set bits per sample"))
+      (unless (FLAC__stream_encoder_set_compression_level enc compression-level) (error 'flac-encoder-configure "could not set compression level"))
+      (unless (FLAC__stream_encoder_set_verify enc (bool->flac-bool verify?)) (error 'flac-encoder-configure "could not set verify"))
+      (unless (FLAC__stream_encoder_set_streamable_subset enc (bool->flac-bool streamable-subset?)) (error 'flac-encoder-configure "could not set streamable subset"))
+      (when (and (integer? blocksize) (> blocksize 0))
+        (unless (FLAC__stream_encoder_set_blocksize enc blocksize) (error 'flac-encoder-configure "could not set blocksize")))
+      (when (and (integer? total-samples) (>= total-samples 0))
+        (unless (FLAC__stream_encoder_set_total_samples_estimate enc total-samples) (error 'flac-encoder-configure "could not set total samples estimate")))
+      #t))
+
+  (define (init file)
+    (require-encoder 'flac-encoder-init)
+    (let ((r (FLAC__stream_encoder_init_file enc file #f #f)))
+      (set! flac-file file)
+      (unless (= r FLAC__StreamEncoderInitStatus-ok)
+        (error 'flac-encoder-init "FLAC encoder init failed with status ~a" r))
+      #t))
+
+  (define (write buffer size buf-info)
+    (require-encoder 'flac-encoder-write)
+    (let* ((channels (hash-ref settings 'channels))
+           (in-bits (hash-ref/default buf-info 'pcm-bits-per-sample
+                                      (hash-ref/default buf-info 'bits-per-sample
+                                                        (hash-ref settings 'bits-per-sample))))
+           (out-bits (hash-ref settings 'bits-per-sample)))
+      (let-values (((ptr frames) (pcm-bytes->flac-int32-pointer buffer size channels in-bits out-bits)))
+        (unless (FLAC__stream_encoder_process_interleaved enc ptr frames)
+          (error 'flac-encoder-write "FLAC encoder process_interleaved failed, state ~a" (FLAC__stream_encoder_get_state enc)))
+        frames)))
+
+  (define (finish)
+    (require-encoder 'flac-encoder-finish)
+    (FLAC__stream_encoder_finish enc))
+
+  (define (delete)
+    (unless (eq? enc #f)
+      (FLAC__stream_encoder_delete enc)
+      (set! enc #f))
+    #t)
+
+  (lambda (cmd . args)
+    (cond [(eq? cmd 'new) (new)]
+          [(eq? cmd 'configure) (configure (car args))]
+          [(eq? cmd 'init) (init (car args))]
+          [(eq? cmd 'write) (write (car args) (cadr args) (caddr args))]
+          [(eq? cmd 'finish) (finish)]
+          [(eq? cmd 'delete) (delete)]
+          [(eq? cmd 'state) (and enc (FLAC__stream_encoder_get_state enc))]
+          [(eq? cmd 'file) flac-file]
+          [(eq? cmd 'settings) settings]
+          [else (error (format "unknown FLAC encoder command ~a" cmd))])))
+
+
 ); end of module