wiki:Help/AudioMapping/SeparateClips

Audio Mapping: Audio clips with waymarks

This method of audio mapping uses waypoints collected using your GPS to identify the position of a feature and separate audio recordings for each one to take notes.

Procedure:

Before you start

  1. Do you have suitable software to link the audio tracks to the GPX file if your GPS doesn't support voice notes directly (there aren't many, but internet tablets with built in GPS offer the possibility)
    • what it needs to do is fairly simple: for each waypoint in the GPX file, a <link> element needs to be added, the href attribute of which contains a file URL referring to the WAV file for that point. If you consistently make a file for each point, it would be readily possibly to edit the XML automatically to add the file references to the waypoints in sequence. Example:
      <wpt lat="39.400611" lon="8.602494">
          <desc>2009-05-30T23:28:33Z</desc>
          <link href="VOX02899.wav"><text>VOX02899.wav</text></link>
      </wpt>
      

While surveying

  1. Do your surveying. Make a waypoint and dictate the corresponding notes in the way prescribed by your GPS receiver, or simply start recording on your voice recorder after making a waypoint, record your notes, and stop (not pause) the recording.
    • Some digital voice recorders limit the number of individual recordings you can make, e.g. to 100, which may be rather limiting in a long mapping session.

On the computer

  1. Extract your tracks from the GPS as a GPX file, and, if the device does not automatically integrate them, your sound tracks from the recorder as WAV files.
    • JOSM (actually, Java's built-in audio facilities) doesn't recognise every variety of WAV file encodings. If you need to (JOSM will tell you), convert your recording to a suitable format using e.g. Audacity. 8,000 16-bit samples per second is a reasonable format.
  1. Open your GPX file. This will create (a) a GPX layer showing the track and (b) a Marker layer containing the waypoints as ready-made Audio Markers.
    • if you don't see audio icons with the Markers, check that Show/Hide Text/Icons on the context menu for the Marker Layer is not off.
    • Otherwise it is most likely JOSM has not recognized the link element in the GPX file. The link must be a URL (often a "file:..." URL) and end in ".wav" to be recognized.
  1. Play each Marker and create the streets and features you described at the locations indicated by the Marker, in the usual way.

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Last modified 9 years ago Last modified on 2009-06-26T12:36:03+02:00