G.711 gives you the 64kbps quality you get on a channel in a PRI line. No compression is performed. G.729 is a well accepted codec that performs compression, and with ip packet overhead, uses about 16 to 24 kbps (can't remember which). It gives voice quality very close to G.711. G.723 has a noticeable voice quality change, and is in the 6 to 8 kbps range. The optimal is G.729 for quality vs bandwidth issues. There are some other considerations involved but these are the main ones. Ray Burkholder
-----Original Message----- From: Charles Youse [mailto:cyouse@register.com] Sent: February 10, 2003 14:42 To: Alec H. Peterson Cc: nanog@nanog.org Subject: RE: VoIP QOS best practices
Speaking of codecs, what are the primary variables one uses when choosing a codec? I imagine this is some function of how much bandwidth you want to use versus how much CPU to encode the voice stream.
C.
-----Original Message----- From: Alec H. Peterson [mailto:ahp@hilander.com] Sent: Monday, February 10, 2003 1:40 PM To: Bill Woodcock; Charles Youse Cc: nanog@nanog.org Subject: RE: VoIP QOS best practices
--On Monday, February 10, 2003 10:19 -0800 Bill Woodcock <woody@pch.net> wrote:
It works fine on 64k connections, okay on many 9600bps
connections. T1 is
way more than is necessary.
I'd say that largely depends on which codec you are using and how many simultaneous calls you will have going.
Alec
-- Alec H. Peterson -- ahp@hilander.com Chief Technology Officer Catbird Networks, http://www.catbird.com
Also note that those sizes are for the voice part of the payload only....It does not take into account any payload/packet overhead... We use G.711 quite a bit on our network, and are traffic flows are right around 80k... Spencer ************************************************************ Spencer Wood, Network Manager Ohio Department Of Transportation 1320 Arthur E. Adams Drive Columbus, Ohio 43221 E-Mail: Spencer.Wood@dot.state.oh.us Phone: 614.644.5422/Fax: 614.887.4021/Pager: 866.591.9954 ************************************************************* "Ray Burkholder" <ray@oneunified.net> Sent by: owner-nanog@merit.edu 02/10/2003 02:21 PM To: "Charles Youse" <cyouse@register.com>, "Alec H. Peterson" <ahp@hilander.com> cc: <nanog@nanog.org> Subject: RE: VoIP QOS best practices G.711 gives you the 64kbps quality you get on a channel in a PRI line. No compression is performed. G.729 is a well accepted codec that performs compression, and with ip packet overhead, uses about 16 to 24 kbps (can't remember which). It gives voice quality very close to G.711. G.723 has a noticeable voice quality change, and is in the 6 to 8 kbps range. The optimal is G.729 for quality vs bandwidth issues. There are some other considerations involved but these are the main ones. Ray Burkholder
-----Original Message----- From: Charles Youse [mailto:cyouse@register.com] Sent: February 10, 2003 14:42 To: Alec H. Peterson Cc: nanog@nanog.org Subject: RE: VoIP QOS best practices
Speaking of codecs, what are the primary variables one uses when choosing a codec? I imagine this is some function of how much bandwidth you want to use versus how much CPU to encode the voice stream.
C.
-----Original Message----- From: Alec H. Peterson [mailto:ahp@hilander.com] Sent: Monday, February 10, 2003 1:40 PM To: Bill Woodcock; Charles Youse Cc: nanog@nanog.org Subject: RE: VoIP QOS best practices
--On Monday, February 10, 2003 10:19 -0800 Bill Woodcock <woody@pch.net> wrote:
It works fine on 64k connections, okay on many 9600bps
connections. T1 is
way more than is necessary.
I'd say that largely depends on which codec you are using and how many simultaneous calls you will have going.
Alec
-- Alec H. Peterson -- ahp@hilander.com Chief Technology Officer Catbird Networks, http://www.catbird.com
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