initial import from racket-sound -> racket-audio
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(module ffmpeg_decoder racket/base
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(require ffi/unsafe
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"ffmpeg-ffi.rkt"
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"private/utils.rkt"
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(prefix-in fin: finalizer)
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)
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(provide ffmpeg-open
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ffmpeg-valid?
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ffmpeg-read
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ffmpeg-stop
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ffmpeg-seek
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)
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(define-struct ffmpeg-handle
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(if cb-info cb-audio
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(stop #:mutable)
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(seek #:mutable)
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(reading #:mutable)
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(format #:mutable)
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)
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#:transparent
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)
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Functions to do the good stuff
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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(define (ffmpeg-valid? audio-file)
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;; Keep this deliberately weak, just like mp3-valid?. Existence and
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;; extension checks can be done by the generic audio-decoder layer. The
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;; real validation happens when the FFmpeg shim opens the file.
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#t)
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(define audio-type 'ffmpeg)
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(define last-rate 44100) ; An assumption for if we've got nothing
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(define last-channels 2) ; An assumption for if we've got nothing
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(define last-bits 32) ; FFmpeg shim output is always S32
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(define last-bytes 4) ; One S32 sample is four bytes
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(define (correct-format-hash h)
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(let ((rate (hash-ref h 'sample-rate #f)))
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(when (eq? rate #f)
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(hash-set! h 'sample-rate last-rate)))
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(let ((channels (hash-ref h 'channels #f)))
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(when (eq? channels #f)
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(hash-set! h 'channels last-channels)))
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(let ((bits (hash-ref h 'bits-per-sample #f)))
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(when (eq? bits #f)
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(hash-set! h 'bits-per-sample last-bits)))
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(let ((bytes (hash-ref h 'bytes-per-sample #f)))
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(when (eq? bytes #f)
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(hash-set! h 'bytes-per-sample last-bytes)))
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(let ((total-samples (hash-ref h 'total-samples #f)))
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(when (eq? total-samples #f)
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(hash-set! h 'total-samples 0)
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(hash-set! h 'duration 0))))
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(define (report-format handle current-pcm-pos)
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(dbg-sound "Reporting ffmpeg format at pcm-pos: ~a" current-pcm-pos)
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(let ((h (ffmpeg-handle-format handle)))
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(set! last-rate (hash-ref h 'sample-rate))
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(set! last-channels (hash-ref h 'channels))
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(set! last-bits (hash-ref h 'bits-per-sample))
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(set! last-bytes (hash-ref h 'bytes-per-sample last-bytes)))
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((ffmpeg-handle-cb-info handle) (ffmpeg-handle-format handle)))
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(define (give-audio handle info pos buffer size)
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(let ((h (ffmpeg-handle-format handle)))
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(correct-format-hash h)
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(hash-set! h 'sample pos)
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(let ((sample-rate (hash-ref h 'sample-rate last-rate)))
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(hash-set! h 'current-time (exact->inexact (/ pos sample-rate))))
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((ffmpeg-handle-cb-audio handle) h buffer size)))
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(define (ffmpeg-open audio-file* cb-stream-info cb-audio)
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(let ((audio-file (if (path? audio-file*)
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(path->string audio-file*)
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audio-file*)))
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(if (file-exists? audio-file)
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(let ((handler (fmpg-ffi-decoder-handler)))
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(handler 'new)
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(handler 'init audio-file)
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(let ((h (make-ffmpeg-handle handler
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cb-stream-info
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cb-audio
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#f
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#f
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#f
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(make-hash))))
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h))
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#f)))
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(define (handle-format handle pcm-pos rate channels sample-bits sample-bytes pcm-length)
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(let ((f (make-hash)))
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(hash-set! f 'duration (if (and (integer? pcm-length)
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(>= pcm-length 0)
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(integer? rate)
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(> rate 0))
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(exact->inexact (/ pcm-length rate))
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0.0))
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(hash-set! f 'sample-rate rate)
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(hash-set! f 'channels channels)
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(hash-set! f 'bits-per-sample sample-bits)
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(hash-set! f 'bytes-per-sample sample-bytes)
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(hash-set! f 'total-samples pcm-length)
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(set-ffmpeg-handle-format! handle f))
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(report-format handle pcm-pos))
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(define (ffmpeg-read handle)
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(let* ((ffi-handler (ffmpeg-handle-if handle))
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(cb-info (ffmpeg-handle-cb-info handle))
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(cb-audio (ffmpeg-handle-cb-audio handle)))
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(set-ffmpeg-handle-reading! handle #t)
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(let loop ()
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(if (eq? (ffmpeg-handle-stop handle) #t)
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(begin
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(dbg-sound "Stopping ffmpeg decoding")
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(set-ffmpeg-handle-reading! handle #f)
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'stopped-reading)
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(begin
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(unless (eq? (ffmpeg-handle-seek handle) #f)
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(dbg-sound "Seeking to ~a" (ffmpeg-handle-seek handle))
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(ffi-handler 'seek (ffmpeg-handle-seek handle))
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(set-ffmpeg-handle-seek! handle #f))
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(ffi-handler 'read
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(lambda (info pos buffer size)
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(if (eq? info 'done)
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(set-ffmpeg-handle-stop! handle #t)
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(give-audio handle info pos buffer size)))
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(lambda (pcm-pos rate channels sample-bits sample-bytes pcm-length)
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(handle-format handle pcm-pos rate channels sample-bits sample-bytes pcm-length)))
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(loop)))))
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(let ((ffi-handler (ffmpeg-handle-if handle)))
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(ffi-handler 'close)
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(ffi-handler 'delete)))
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(define (ffmpeg-seek handle percentage)
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(let ((fmt (ffmpeg-handle-format handle)))
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(let ((total-samples (hash-ref fmt 'total-samples 0)))
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(unless (or
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(eq? total-samples #f)
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(= total-samples -1))
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(let ((sample (inexact->exact
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(round (* (exact->inexact (/ percentage 100.0))
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total-samples)))))
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(set-ffmpeg-handle-seek! handle sample))))))
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(define (ffmpeg-stop handle)
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(set-ffmpeg-handle-stop! handle #t)
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(while (ffmpeg-handle-reading handle)
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(sleep 0.01)))
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); end of module
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