92 lines
3.2 KiB
Racket
92 lines
3.2 KiB
Racket
#lang racket/base
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;; Generate the DIDL-Lite description passed to AVTransport actions.
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(require racket/format
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xml)
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(provide didl-lite-audio-item)
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(define (check-string who value)
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(unless (string? value)
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(raise-argument-error who "string?" value)))
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(define (duration->string who duration)
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(unless (and (rational? duration)
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(not (negative? duration)))
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(raise-argument-error who "nonnegative-real?" duration))
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(let* ([seconds (inexact->exact (floor duration))]
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[hours (quotient seconds 3600)]
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[remaining (remainder seconds 3600)]
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[minutes (quotient remaining 60)])
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(format "~a:~a:~a"
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hours
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(~r minutes #:min-width 2 #:pad-string "0")
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(~r (remainder remaining 60)
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#:min-width 2
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#:pad-string "0"))))
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(define (didl-lite-audio-item uri
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#:protocol-info protocol-info
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#:title [title "Media"]
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#:artist [artist #f]
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#:album [album #f]
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#:genre [genre #f]
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#:year [year #f]
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#:track [track #f]
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#:duration [duration #f]
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#:size [size #f]
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#:id [id "0"]
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#:parent-id [parent-id "0"])
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(check-string 'didl-lite-audio-item uri)
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(check-string 'didl-lite-audio-item protocol-info)
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(check-string 'didl-lite-audio-item title)
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(check-string 'didl-lite-audio-item id)
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(check-string 'didl-lite-audio-item parent-id)
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(for ([value (in-list (list artist album genre))])
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(unless (or (not value) (string? value))
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(raise-argument-error
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'didl-lite-audio-item
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"(or/c #f string?)"
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value)))
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(for ([value (in-list (list year track))])
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(unless (or (not value) (exact-nonnegative-integer? value))
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(raise-argument-error
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'didl-lite-audio-item
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"(or/c #f exact-nonnegative-integer?)"
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value)))
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(unless (or (not size)
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(exact-nonnegative-integer? size))
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(raise-argument-error
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'didl-lite-audio-item
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"(or/c #f exact-nonnegative-integer?)"
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size))
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(xexpr->string
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`(DIDL-Lite
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((xmlns "urn:schemas-upnp-org:metadata-1-0/DIDL-Lite/")
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(xmlns:dc "http://purl.org/dc/elements/1.1/")
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(xmlns:upnp "urn:schemas-upnp-org:metadata-1-0/upnp/"))
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(item
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((id ,id)
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(parentID ,parent-id)
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(restricted "1"))
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(dc:title () ,title)
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(upnp:class () "object.item.audioItem.musicTrack")
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,@(if artist `((upnp:artist () ,artist)) '())
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,@(if album `((upnp:album () ,album)) '())
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,@(if genre `((upnp:genre () ,genre)) '())
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,@(if year `((dc:date () ,(number->string year))) '())
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,@(if track
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`((upnp:originalTrackNumber () ,(number->string track)))
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'())
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(res
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((protocolInfo ,protocol-info)
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,@(if duration
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`((duration
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,(duration->string 'didl-lite-audio-item duration)))
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'())
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,@(if size
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`((size ,(number->string size)))
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'()))
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,uri)))))
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