[ntp:questions] Using NTP to calibrate sound app

Rob nomail at example.com
Sat Jan 26 10:21:35 UTC 2013


no-one at no-place.org <no-one at no-place.org> wrote:
> Now I am considering an alternate means of performing this calibration
> using NTP.  The iPhone and Android devices deliver audio to my app in
> small packets.  A calibration run would consist of an initial NTP
> syncronization with an audio packet, followed by a period of some
> number of minutes during which I will just count audio packets,
> followed by a final NTP synchronization with the last audio packet.
> By knowing the time difference over some number of audio packets I
> hope to calculate the actual audio clock frequency for that device.

I think the average internet connection from a device like an iPhone
has so much jitter that this approach will not work reasonably well.
(try to ping to an internet server and see what kind of jitter you
have, it usually is terrible over UMTS, WiFi etc)



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