didl toevoegingen

scribblings/didl-lite.scrbl

@@ -0,0 +1,45 @@
+#lang scribble/manual
+
+@(require
+  (for-label
+   racket/base
+   (file "../didl-lite.rkt")))
+
+@title{DIDL-Lite Metadata}
+
+@defmodule[(file "../didl-lite.rkt")]
+
+DIDL-Lite describes the resource passed to a renderer.  Some renderers only
+advertise seeking after the current URI has metadata containing its media
+type, duration, and byte-range capability.
+
+@defproc[(didl-lite-audio-item
+          [uri string?]
+          [#:protocol-info protocol-info string?]
+          [#:title title string? "Media"]
+          [#:duration duration (or/c #f nonnegative-real?) #f]
+          [#:size size (or/c #f exact-nonnegative-integer?) #f]
+          [#:id id string? "0"]
+          [#:parent-id parent-id string? "0"])
+         string?]{
+
+Returns an XML DIDL-Lite audio-item description.  Text and attribute values
+are XML-escaped automatically.
+
+The @racket[protocol-info] value must describe the HTTP resource accurately.
+For example:
+
+@racketblock[
+(didl-lite-audio-item
+ "http://10.7.3.118:8080/media/test.flac"
+ #:protocol-info
+ "http-get:*:audio/flac:DLNA.ORG_OP=01;DLNA.ORG_CI=0"
+ #:title "Test track"
+ #:duration 639
+ #:size 50357462)
+]
+
+Use @racket[media-file-server-didl-lite] when the URI was published with this
+package; it fills in the protocol information and file size from the actual
+publication.
+}

scribblings/media-file-server.scrbl

@@ -3,6 +3,7 @@
 @(require
   (for-label
    racket/base
+   (file "../didl-lite.rkt")
    (file "../media-file-server.rkt")))
 
 @title{Publishing Media Files}
@@ -77,6 +78,26 @@ Removes the URL mapping.  Requests that are already in progress may still
 finish.
 }
 
+@defproc[(media-file-server-didl-lite
+          [server media-file-server?]
+          [url string?]
+          [#:title title (or/c #f string?) #f]
+          [#:duration duration (or/c #f nonnegative-real?) #f]
+          [#:id id string? "0"]
+          [#:parent-id parent-id string? "0"])
+         string?]{
+
+Returns DIDL-Lite metadata for a URL previously installed with
+@racket[media-file-server-publish!].  The MIME type, file size, and
+@tt{DLNA.ORG_OP=01} byte-range capability are taken from the actual
+publication.  The file name is used as the title when @racket[title] is
+@racket[#f].
+
+Pass the result as @racket[#:metadata] or @racket[#:next-metadata] to the
+media-renderer functions.  Supplying the duration is recommended because some
+renderers use it when deciding whether time seeking is available.
+}
+
 @defproc[(media-file-server-stop!
           [server media-file-server?])
          void?]{
@@ -104,10 +125,26 @@ Stops the web server.  Repeated calls have no effect.
    "C:/muziek/second.flac"
    "second.flac"))
 
+(define first-metadata
+  (media-file-server-didl-lite
+   files
+   first-uri
+   #:title "First track"
+   #:duration 639))
+
+(define second-metadata
+  (media-file-server-didl-lite
+   files
+   second-uri
+   #:title "Second track"
+   #:duration 242))
+
 (media-renderer-play-uri!
  renderer
  first-uri
- #:next-uri second-uri)
+ #:metadata first-metadata
+ #:next-uri second-uri
+ #:next-metadata second-metadata)
 ]
 
 Keep the URLs published until the renderer has finished reading them.

scribblings/media-renderer.scrbl

@@ -3,6 +3,7 @@
 @(require
   (for-label
    racket/base
+   (file "../media-file-server.rkt")
    (file "../media-renderer.rkt")))
 
 @title{Media Renderers}
@@ -80,10 +81,15 @@ included in the UPnP device description.
 
 Sets @racket[uri] as the current resource and starts playback.
 
+Supply DIDL-Lite in @racket[metadata].  Although AVTransport permits an empty
+string, some renderers do not enable seeking without resource metadata.  Use
+@racket[media-file-server-didl-lite] for resources published by this package.
+
 When @racket[next-uri] is supplied, it is installed with
 @tt{SetNextAVTransportURI} before playback starts.  A supporting renderer can
 open and buffer the next resource while the current resource is playing,
-allowing a gapless or near-gapless transition.
+allowing a gapless or near-gapless transition.  Supply matching DIDL-Lite in
+@racket[next-metadata].
 }
 
 @defproc[(media-renderer-play! [renderer media-renderer?]) any]{
@@ -107,7 +113,8 @@ Reports whether the renderer advertises the optional
 
 Sets the resource that follows the currently playing resource.  The action
 describes one next resource, not a complete queue.  After playback advances to
-that resource, call this function again to preload the following track.
+that resource, call this function again to preload the following track.  Use
+metadata that describes @racket[uri], not the current resource.
 }
 
 @defproc[(media-renderer-pause! [renderer media-renderer?]) any]

scribblings/racket-upnp.scrbl

@@ -5,6 +5,7 @@
 
 @include-section["intro.scrbl"]
 @include-section["main.scrbl"]
+@include-section["didl-lite.scrbl"]
 @include-section["media-renderer.scrbl"]
 @include-section["media-server.scrbl"]
 @include-section["media-file-server.scrbl"]