Prefetching
This commit is contained in:
+113
-30
@@ -126,10 +126,13 @@
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(define temporary-media #f)
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(define current-media-key #f)
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(define cached-media (make-hash))
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(define prefetched-track #f)
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(define auto-started-key #f)
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(define pending-auto-music-id #f)
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(define music-tracks (make-hash))
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(define current-track #f)
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(define acknowledged-command 0)
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(define ended-counter 0)
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(define eof-pending? #f)
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(define logical-volume 50)
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(define agent-state
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(hasheq 'state "stopped"
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@@ -164,10 +167,11 @@
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(define (update-from-audio! state full-state)
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(with-agent-state
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(λ ()
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(define normalized (normal-state state))
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(define audible-music-id
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(hash-ref full-state 'at-music-id #f))
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(set! agent-state
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(hasheq
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'state normalized
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'state (normal-state state)
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'position
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(state-value (hash-ref full-state 'at-second #f) 0)
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'duration
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@@ -183,10 +187,16 @@
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(if decoder (format "~a" decoder) ""))
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'volume logical-volume
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'error 'null))
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;; racket-audio reports decoder EOF before its output buffer has
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;; drained. Advance only when playback itself has actually stopped.
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(when (and eof-pending? (string=? normalized "stopped"))
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(set! eof-pending? #f)
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(when (and pending-auto-music-id
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(number? audible-music-id)
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(= pending-auto-music-id audible-music-id))
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(let ((audible-track
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(hash-ref music-tracks audible-music-id #f)))
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(when audible-track
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(set! current-track audible-track)
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(hash-clear! music-tracks)
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(hash-set! music-tracks audible-music-id audible-track)))
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(set! pending-auto-music-id #f)
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(set! ended-counter (+ ended-counter 1))))))
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(define (set-agent-error! message)
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@@ -211,10 +221,8 @@
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(make-audio-player
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(λ (_handle state full-state)
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(update-from-audio! state full-state))
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(λ (_handle)
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(with-agent-state
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(λ ()
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(set! eof-pending? #t))))))
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(λ (handle)
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(advance-at-decoder-eof! handle))))
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(audio-ao-buf-ms! audio 500)
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(audio-buf-seconds! audio 4 10)
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(let ((scaled (/ logical-volume 100.0)))
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@@ -266,33 +274,104 @@
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(safe-delete-file (cdr entry))
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(hash-remove! cached-media (car entry)))))
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;; Decoder EOF is intentionally earlier than audible EOF: racket-audio may
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;; still have several seconds buffered in libao. Starting the prepared file
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;; here appends it to that same output queue, which is the gapless transition
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;; used by rktplayer as well.
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(define (advance-at-decoder-eof! handle)
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(define prepared
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(with-agent-state
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(λ ()
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(let ((value prefetched-track))
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(set! prefetched-track #f)
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value))))
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(cond
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(prepared
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(let* ((data (car prepared))
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(path (cdr prepared))
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(key (command-cache-key data)))
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(with-handlers
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((exn:fail?
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(λ (exception)
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(warn-player-agent
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"Could not start prefetched track: ~a"
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(exn-message exception))
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(set-agent-error! (exn-message exception))
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(with-agent-state
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(λ ()
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(set! ended-counter (+ ended-counter 1)))))))
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(define music-id (audio-play! handle path))
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(info-player-agent
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"Queued prefetched track ~a as music id ~a"
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(hash-ref data 'filename "track")
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music-id)
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(set! current-media-key key)
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(set! temporary-media path)
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(discard-unused-media! key)
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(with-agent-state
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(λ ()
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(hash-set! music-tracks music-id data)
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(set! auto-started-key key)
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;; Inform the server only when libao reports this id as audible,
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;; not while the preceding track is still draining.
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(set! pending-auto-music-id music-id))))))
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(else
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;; The server-driven fallback remains available when prefetching did
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;; not complete before EOF.
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(warn-player-agent
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"Decoder reached EOF before the next track was prefetched")
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(with-agent-state
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(λ ()
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(set! ended-counter (+ ended-counter 1)))))))
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(define (execute-command! command)
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(let* ((action (hash-ref command 'action ""))
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(data (hash-ref command 'data (hasheq))))
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(info-player-agent "Executing command ~a" action)
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(cond
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((string=? action "play")
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(with-agent-state (λ () (set! eof-pending? #f)))
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(set! current-track data)
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(with-agent-state
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(λ ()
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(set! agent-state
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(hash-set
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(hash-set agent-state 'state "starting")
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'error
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'null))))
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(let* ((next-key (command-cache-key data))
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(next-media (ensure-media-cached! data)))
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;; audio-play! already interrupts and closes the previous decoder.
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;; Calling audio-stop! first can delete a finished FLAC decoder a
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;; second time in racket-audio.
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(audio-play! (ensure-audio!) next-media)
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(set! current-media-key next-key)
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(set! temporary-media next-media)
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(discard-unused-media! next-key)))
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(already-started?
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(with-agent-state
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(λ ()
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(let ((matches?
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(and auto-started-key
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(equal? auto-started-key next-key))))
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(when matches? (set! auto-started-key #f))
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matches?)))))
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(set! current-track data)
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(unless already-started?
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(with-agent-state
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(λ ()
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(set! prefetched-track #f)
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(set! auto-started-key #f)
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(set! pending-auto-music-id #f)
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(set! agent-state
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(hash-set
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(hash-set agent-state 'state "starting")
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'error
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'null))))
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(let ((next-media (ensure-media-cached! data)))
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;; audio-play! already interrupts and closes the previous
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;; decoder; an extra audio-stop! can double-delete FLAC.
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(define music-id
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(audio-play! (ensure-audio!) next-media))
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(with-agent-state
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(λ ()
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(hash-clear! music-tracks)
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(hash-set! music-tracks music-id data)))
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(set! current-media-key next-key)
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(set! temporary-media next-media)
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(discard-unused-media! next-key)))))
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((string=? action "prefetch")
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(let ((key (command-cache-key data)))
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(ensure-media-cached! data)
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(let ((path (ensure-media-cached! data)))
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(with-agent-state
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(λ ()
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(set! prefetched-track (cons data path))))
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(info-player-agent
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"Prefetched ~a"
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(hash-ref data 'filename "track")))
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;; Retain the playing file and the one prepared for playback.
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(for ((entry (in-list (hash->list cached-media))))
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(unless (or (equal? (car entry) current-media-key)
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@@ -304,7 +383,11 @@
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((string=? action "resume")
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(audio-pause! (ensure-audio!) #f))
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((string=? action "stop")
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(with-agent-state (λ () (set! eof-pending? #f)))
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(with-agent-state
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(λ ()
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(set! prefetched-track #f)
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(set! auto-started-key #f)
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(set! pending-auto-music-id #f)))
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(when audio (audio-stop! audio)))
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((string=? action "seek")
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(audio-seek! (ensure-audio!)
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