[Asterisk-Dev] u2linear conversion error?

Steve Underwood steveu at coppice.org
Thu Jun 9 06:02:00 MST 2005

Bob Carlson wrote:

>I have been looking at the actual waveforms produced by an audio stream
>translated from ulaw into slinear. The source of the ulaw stream is a
>Grandstream SIP phone. The wave form is clearly biased in one direction
>relative to the x-axis. My guess is that either the SIP phone is making a
>mistake in applying the bias factor as it encodes the ulaw or * is
>misapplying the bias as it decodes the ulaw.
>I could figure this out, but I just don't have the time before I head off
>on vacation on Friday. Does anyone know if the Grandstream phone has an
>encoding error, or might we be dealing with an error in the * decode?
>BTW, I HAVE looked at the * ulaw to slinear code and I have looked at some
>reference code that I found. Without some sustained time to study it, I
>can't yet be sure if the * code is correct.
>Cheers, Bob
Its far more likely to be DC in the signal itself.


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