= Audio Mapping: Continuous audio with GPS waymarks =

This method of audio mapping uses waypoints collected using your GPS
to identify the position of a feature and a continuous audio recording
to take notes. Synchronization and calibration of the sound track
provide a convenient means to play back the notes for each waypoint,
but aren't critical to the geography of the map.

== Procedure: ==

=== Before you start ===

 1. Consider [wiki:Help/HowTo/AudioMapping/Calibration calibrating] your voice recorder.

=== While surveying ===

 1. Start your voice recorder and obtain a fix with your GPS.
    * It is just a little easier to synchronize if you start the voice recorder first.
 
 2. One you have a fix, you might want to start moving just to make sure your location is clear.

 3. Simultaneously add a waypoint to the GPS and add an audio cue to the sound track, for example "synchronization cue.... NOW!".

 4. Do your surveying. Whenever you want to dictate notes, make a waypoint on your GPS just before you speak. For points of interest, be sure the waypoint will indicate its location; for street names you just need to be sure there won't be any ambiguity in the position.
    * If your GPS doesn't allocate a number to the waypoint automatically, consider giving it a name.
    * Ideally, dictate the waypoint name/number before describing it: "point 32: C of E Church, St Luke's, on left set back 30m from the road"

=== On the computer ===

 1. Extract your tracks from the GPS as a GPX file, and your sound track from the recorder as a WAV file.
    * 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. [http://audacity.sourceforge.net/ Audacity]. 8,000 16-bit samples per second is a reasonable format.

 2. [wiki:Help/Action/Open Open] your GPX file. This will create a GPX layer showing the track.
    * if you have explicit waypoints in your GPX file you will also probably see a Marker Layer for those waypoints. You will most likely want to turn this behaviour off by un-checking 'Create non-audio markers when reading GPX' in [wiki:Help/Preferences/Audio Audio Preferences].

 3. Import your audio file using [wiki:Help/Action/ImportAudio Import Audio] on the GPX layer's context menu. After you identify your WAV file you should see a Marker Layer with audio markers for your waypoints.
    * if you only see one markers at the start:
      (a) you may have turned off 'Import audio uses expolicit waypoints' in [wiki:Help/Preferences/Audio Audio Preferences].
      (b) it is possible your GPS represents your marks by giving names/numbers to particular points on the track rather than separate waypoints. JOSM will recognize these while importing audio if you turn on the 'Create markers from named trackpoints' option in [wiki:Help/Preferences/Audio Audio Preferences].
    * If you don't see your names or numbers along with he Audio Marker icons, check that the 'Label audio markers' option in [wiki:Help/Preferences/Audio Audio Preferences] is on.

 4. [wiki:Help/AudioMapping/Synchronization Synchronize] your sound track to the GPS data. There are [wiki:Help/AudioMapping/Synchronization two ways] of doing this.

 5. Play each Marker and create the streets and features you described at the locations indicated by the Marker, in the usual way.
    * If you start finding gaps in play back before you hear what you expect, or audio starts part way into your comment:
      a. you may not have [wiki:Help/HowTo/AudioMapping/Calibration calibrated] correctly
      b. you may have been speaking too soon or too late while mapping: you can insert a lead-in time to compensate for this using 'Lead-in time' in [wiki:Help/Preferences/Audio Audio Preferences].
      c. you may need to re-synchronize (as per 4 above) on a later marker (perhaps you paused while making the recording). Re-synchronization only affects later markers, so earlier ones will not change.

You can also use the [wiki:Help/Menu/Audio audio controls] to pause, play back etc. and you
can drag the orange play head marker around to jump to a particular
point in the recording.

Back to [wiki:Help/HowTo/AudioMapping Audio Mapping]

Back to [wiki:Help Main Help]