Steve
Trying to understand the floating point vs fixed, forgive my ignorance.
By floating you mean it can very depending on usage from 6.4kbps to
11.8kbps; were as the fixed will be constant 8kbps?
Thanks
Todd
----- Original Message -----
From: "Steve Underwood" <[EMAIL PROTECTED]>
To: "Asterisk Users Mailing List - Non-Commercial Discussion"
<asterisk-users@lists.digium.com>
Sent: Wednesday, May 25, 2005 5:14 AM
Subject: Re: [Asterisk-Users] G729 codec
Ivan Meic (Vox Mundi) wrote:
Actually G.729A is a reduced complexity version, and G.729B is a version
with silence suppression. The data rate while sending voice is exactly
the same, although the quality of G.729B should be a little higher.
However the average rate for B can be lower if the silence suppression is
used. Right now Asterisk doesn't make use of that silence suppression, so
it makes not difference.
Steve,
Any Cisco gateway support two G.729 variants.
They call them g729r8 and g729br8.
Those are versions with different bit packing. Cisco started using G.729
before the packing order was standardised. They guessed it wrong. They had
to change. :-)
So I guess that Cisco never implemented a reduced complexity version ?
Also as far as I understand there are 3 G.729 variants generaly used.
The first version (G.729), Annex A and Annex B.
Are they all compatible with each others ?
There are Annexes up to I. The earlier versions are fixed point, reduced
complexity fixed point and floating point at 8kbps. These are all
compatible. Later annexes add (if memory serves me correctly) silence
suppression, assistance for packet loss concealment (some people say G.729
includes PLC. It doesn't. What it includes is some features to reduce how
badly PLC works with it), the standard for bit packing, and additional bit
rates of 6.4kbps and 11.8kbps.
Regards,
Steve
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