[Asterisk-Users] g711 ulaw vs alaw

[Peter Svensson]

On Thu, 16 Dec 2004, Roger Schreiter wrote:

> Whisker, Peter schrieb:
> > Partly is is down to the fact that G.711u (mu-law) is primarily used in the
> > USA and G.711a (a-law) is used in Europe.
> > 
> > Like you, I am not sure if the exact differences - they have the same
> > bitrate and audio, although there are minor differences in the format.
> > 
> it is just a small difference in how to interpret
> one bit (signed value vs. unsigned value with offset).

I think there is a bit more difference. The byte code of ulaw is a 
monotonic function of the amplitude whereas in alaw the code is xor:ed 
with a bit mask of 0x55. 

Also, the quatization function is different, though the same general idea 
is used. If the difference is important to you you should read the 
standard itself.

Peter