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SongTrellis |
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What are SongTrellis OPML Indexes? When a score includes melody and chord voices, like many of those recorded in the Our Composers section of the site, subheading sequences are produced whose entries point at each phrase in every voice of a score, and at each individual bar in the score. (Soon we will include a subheading sequence that describes every note in all of the voices of a piece.) The OPML indexes created for scores from The Changes section of the site include subheadings that describe the bar sequence in the piece. A phrase description section is also emitted for a Changes score, but frequently that shows the chord progression is one large phrase because there is no change of harmonic rhythm throughout the piece (ie. all chords are of the same duration). When these OPML indexes are opened with an appropriate OPML application (Dave Winer's free OPML Editor or Userland's inexpensive"Radio Userland"), double clicking on a subheading causes the music described by that heading to be played in your web browser. After special add-on customization code is loaded into those programs (available soon from SongTrellis, use the Feedback link above to ask for an early copy), you can select across one or more subheadings in the outline and request that the excerpt that corresponds to that larger subheading selection be delivered to your computer and be played by your web browser.Using these tools, it's not necessary for you to type in the identifying coordinates of the boundary of the excerpt you would like to listen to, as is necessary when you use the SongTrellis pages for the Excerpt Service. Those coordinates are stored within each OPML subheading. This allows the OPML editor to immediately send an excerpt request to the SongTrellis site when you click on a subheading in uncustomized editors or issue a Play, Loop or Deliver Excerpt command from a customized editor. Selecting a sequence of descriptive subheadings in the OPML index in a customized editor identifies the excerpted music that you wish to listen to. How are the SongTrellis OPML indexes created? When you click the link for a tune's OPML index, a request is sent to a Macintosh server that runs a copy of the SongTrellis Music Editor. The editor opens the MIDI file for that score stored on the SongTrellis site, issues a special Save command that creates the OPML index and sends it back to the main SongTrellis server for delivery to your computer, in a fraction of a second. It was very easy to create an OPML emitter for the SongTrellis Editor. I would encourage the authors of other media editors to write code to allow the creation of media indexes using their applications. Web users need ways to reach inside musical works, radio programs, films and other types of performances to allow users to quickly find the parts that most interest them. The focusing capability provided by a media index is useful to casual listeners or viewers and is very important for those who study performances closely to develop their own artistic ability and judgement.
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Last update: Tuesday, October 11, 2005 at 5:38 PM. |
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