[ntp:questions] Accuracy of audio tones via VOIP
david at ex.djwhome.demon.invalid
Tue Jul 9 23:08:05 UTC 2013
On 09/07/13 20:25, Robert Scott wrote:
> That does not sound too encouraging for the pitch accuracy of tones
> transmitted over Skype. Of course you would never notice it in normal
> speech, which is, I guess, all that Skype is targetting. But for
> calibrating to the standard frequency tones from NIST (500 Hz and 600
> Hz), it probably is not trustworthy, right?
You are assuming that it uses a codec providing a 3.1kHz audio, rather
than a speech, bearer service. That is very unlikely. I think you will
find that pure tones are completely mutilated, particularly with respect
to phase, in Skype, because it will actually use a vocoder based codec.
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