Audio Mapping: Continuous audio with GPS waymarks

Procedure:

Before you start

1. Consider calibrating your voice recorder.

While surveying

1. Start your voice recorder and obtain a fix with your GPS.

2. One you have a fix, you might want to start moving just to make sure your location is clear.

3. Simulteneously 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.

2. 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.

3. Open your GPX file. This will create (a) a GPX layer showing the track and (b) a Marker layer containing the waypoints.
   • if you don't see Markers, it is possible your GPS represents these by giving names/numbers to particular points on the track rather than separate waypoints. You can make Markers from these explicitly using Markers From Named Points from the context menu of the GPX layer; and automatically by turning on the 'Create markers from named trackpoints' option in Audio Preferences.
   • if you don't see your number or names with the Markers, check that Show/Hide Text/Icons on the context menu for the Marker Layer is not off.

4. Associate your Audio file with the Marker Layer using Apply Audio on the layer's context menu.
   • If you don't see your names or numbers along with he Audio Marker icons, check that the 'Label audio markers' option in Audio Preferences is on.

5. Start synchronizing your sound track to the GPS data by clicking the icon for the waypoint you made at the synchronization cue. This should start playing your sound track.
   • if you don't see an orange play head arrow moving along the track while you play audio, make sure the 'Display live audio trace' option in Audio Preferences is on.

6. When you hear your synchronization cue ("NOW!"), pause the play back.
   • if you started the recorder <em>after</em> getting a GPS fix, you will need to jump backwards in the sound track. Don't click on an earlier marker, if any, to do this, as that would synchronize to the wrong marker.

7. Select Synchronize Audio on the context menu for the Marker Layer.
   • The play head should jump back to the marker, and when you play the marker you should hear your "NOW!" cue. Clicking on other markers should offer the audio you recorded when you made that marker.

8. 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:
     1. you may not have calibrated correctly
     2. 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 Audio Preferences.
     3. you may need to re-synchronize (as per 5ff above) on a later marker (perhaps you paused while making the recording). Re-synchronization only affects later markers, so earlier ones will not change.

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