OK, I think from a quick scan you need <link href='uri'/> in a waypt or trkpt element where uri is e.g. "file:://pathname.wav" (which I think can be relative).
If you can I'd add a waypoint or trackpoint at the time you press the button, rather than adding it to the most recent trackpoint. You could also auto-number the points so the labels show up in JOSM (trackpoints can be selectively and explicitly named so you don't need separate waypoints) But I wonder whether it is worth it. Unless you are going to go deeply into the phone's track recording mechanism, you're going to be trying to postprocess the track to introduce <link> elements, when just getting the timestamps right is easier. In either case you still need to at least check the calibration. Only if you can get a button on the phone to simultaneously introduce a waypoint with a link and start the recorder at exactly the same time are you going to avoid this. I can't help feeling you're making work for yourself (though it may be the challenge that's interesting you). Calibration is a one off thing and synchronisation is a matter of seconds to do when loading a track. I think getting the timestamps right is likely to be a lot easier than changing the way the GPX file is generated; and recording a continuous track is easier still (though your phone may limit the length of the recording in which case you have little choice). David On 28/03/2009 10:13, Graham Jones (Physics) wrote: > David, > Thanks for the comprehensive reply! > > My idea is similar to your option (b). What I envisage doing is > pressing a button on the phone which then records an audio clip, and > associates the GPS location with that clip. These will be saved on the > phone's memory. > It will then be necessary to export the clips and locations to JOSM - > the simplest answer sounds like the use of a GPX file with references to > the audio clips - it will effectively be like setting a waypoint on a > Garmin GPS device, but without the trouble of trying to type in the name > with the silly little joystick while avoiding traffic.... Therefore if > you could point me to what the <link> specification needs to be for > JOSM, that would be very useful please. > > The phone creates the clips in 'amr' format, but it shouldn't be > difficult to post-process these into WAV, either as a separate > application or as part of a JOSM plugin. I'll not try to do that on the > phone just yet. > > I'll try to get the storage bit working, then should be able to publish > something for people to try.... > > > Graham. > > 2009/3/27 David Earl <[email protected] > <mailto:[email protected]>> > > On 27/03/2009 21:21, Graham Jones (Physics) wrote: > > I am after a simple way of recording street names when cycling > rather than having to write them down. There is a section on > the Wiki on "Audio Mapping", but there is no mention of using a > normal mobile phone and bluetooth GPS receiver - the idea is to > record audio clips and associated location to import into JOSM > later. The advantage of a phone over the other methods is that > it should be able to record both audio, and GPS location at the > same time, to avoid the synchronisation problems. It is also > nice and small, and you don't look odd talking into one. It > might even be possible to use a bluetooth headset which would be > even easier for cycling... > > I have had a bit of a play and I think I can make it work (the > GPS receiver can talk to the phone, and the phone can record > sounds), but I haven't stitched it together in to a single > application yet. I can't help but think that someone will have > tried this before (and presumably failed because I can't find it > anywhere?) - does anyone know if I am onto a loser before I go > too far down the road of coding it? There is a bit more > information at > > http://wiki.openstreetmap.org/wiki/Talk:Audio_mapping#Mobile_Phone_Version.3F > > Any pointers to where this is going to go wrong would be > appreciated! > > > Hi Graham, > > I wrote the audio bits in JOSM, so I can tell you what goes on at > that end, and I also added a new bit recently to support something > similar to this (so make sure you have a JOSM from the last couple > of weeks - I'd have to check for the exact build number). > Incidentally, the help in JOSM is more comprehensive than the help > OSM wiki page. > > However, a word of caution: the fact they are on the same device > doesn't necessarily mean you can dispense with sync or calibration. > It is quite likely the GPS track will generate its time stamps from > the GPS satellite time and the audio manage its sampling and time > stamps from the clock on the phone. They may not correspond exactly > (indeed you probably have to set the one on the phone explicitly) > and may drift a small amount. I think you should check this first. > You may be lucky, but don't take it for granted. An error of only > second or two can make quite a big difference and even if you can > set the phone clock to the same as the GPS a drift of only 0.1% can > make 100m difference on a long continuous recording. > > How to proceed depends on whether you're recording a continuous > sound track or a set of snippets. > > In all cases you need WAV files. If your phone records another > format you'll need to convert them to WAV (e.g. using Audacity). > > If many, short files then there are two approaches > > (a) have a set of WAV files whose (modified) time stamps are those > of the original recordings (i.e. if you converted them, you'll need > to use touch to bring the timestamps into sync with the original files). > > Tick the appropriate box in the audio preferences to say this is how > you want to work. > > Then when you import audio for a track choose _all_ the files (using > shift and ctrl click as appropriate in the file chooser dialog). > That will associate the audio clips at those time points along the > track. NOTE: the time stamps are those at the *end* of each > recording (for obvious reasons, I hope), but JOSM will take this > into account, so the point identified on the track will be at the > *beginning* of the recording. > > (b) postprocess the GPX file to add <link> elements to the relevant > trackpoints to refer to audio files. This is a manual equivalent of > the above. If you want to try this, let me know and I'll look up the > exact spec of the <link> tag for you. > > For a continuous recording, you would still need to sync, because it > is unlikely your track and recording will start at the same moment. > However, if you start the recording at the same moment you make a > waypoint, you won't need to record anything to mark the sync, it > will just be precisely the beginning of the recording, so you can > just briefly start playing and then immediately stop the audio from > the first waymark and sync. (Actually that's true anyway, you could > do this on any recorder). > > HTH > > David > > > > > -- > Dr. Graham Jones > Hartlepool, UK > email: [email protected] <mailto:[email protected]> _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev
