audio sampling Skews!
 

hi, i am working on the Zaurus handheld and am trying to have a bunch of these devices simultaneously record audio with a microphone. ideally, given that all Zauri "hear" the same sound, the resulting audio files would be almost exactly the same. for example, a clicking sound at regular 1 second intervals results in audio files that produce clicking sounds at regular 1 second intervals.

however, the problem is that the resulting audio files are NOT the exactly the same. after an hour or so, the audio files are off by up to 2 seconds which is unacceptable. doh!

i am looking for suggestions. is it hardware, software, or other related? how can i test and experiment to hopefully identify the problem? thanks.

-Tim

Re: audio sampling Skews!
 

slight variations in sample rate, perhaps... as to why this is happening.. issues with multitasking, maybe? or varying processor/RTC speeds... 2 seconds in an hour is less than 0.03% variance

i've determined the problem/solution
 

google lead me to the answer: UCLA published a paper about their solution to synchronizing audio-recording on several devices (iPAQs). apparently, the problem is, essentially, that different devices have different clock sampling rates. Also, audio hardware has its own clock which causes further variation in audio sampling.

http://lecs.cs.ucla.edu/Publications...ots-sensor.pdf