Nope. The floating point vs fixed point thing is something that has no
effect on the ordinary user.
It is a matter of the internal implementation of the codec, and the type
of processors on which it can run. The only thing the ordinary user
needs to know is that what is sent out and expected as input by these
two codecs is the same.
Regards,
Steve
todd wrote:
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"
<[email protected]>
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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