Velocity Reviews - Computer Hardware Reviews

Velocity Reviews > Newsgroups > Computing > VOIP > Does G.711 have silence suppression?

Reply
Thread Tools

Does G.711 have silence suppression?

 
 
Alex
Guest
Posts: n/a
 
      07-31-2003
Hi,

I've read that G.711 doesnt compress voice data and operates at 64kbps.
But does this standard have silence suppression?

Thanks.


 
Reply With Quote
 
 
 
 
Bebop
Guest
Posts: n/a
 
      08-01-2003
Alex <(E-Mail Removed)> wrote:

> Hi,
>
> I've read that G.711 doesnt compress voice data and operates at 64kbps.
> But does this standard have silence suppression?
>
> Thanks.



Yes, most codecs have the silence suppression feature.
 
Reply With Quote
 
 
 
 
Cybraxis
Guest
Posts: n/a
 
      08-01-2003
The basic G.711 standard does not include a silence detector (aka VAD, voice
activity detection). Most system level implementations of G.711 with VoIP
use a proprietary VAD on the TDM/analog side of the 'codec'.

G.711 appendix A and B add VAD and spectrally matched comfort noise
generation as standards, so you should start to see them filter through in
commercially available implementations of G.711 about now.

To say G.711 doesn't compress voice is not accurate. Voice starts of as an
analog signal and is typically compressed (or rather companded) to a
PCM/G.711 64kbps stream. This carries less information that the original
analog signal, so technically it is compressed. However if you are starting
with a voice signal already on a digital network (T1/E1 etc) then it will
already be PCM/G.711 companded, so going top G.711 on a packet network
doesn't compress it any further.....in fact the packetization overhead will
require more bandwidth than is needed to carry PCM on the original TDM
serial stream.

"Alex" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Hi,
>
> I've read that G.711 doesnt compress voice data and operates at 64kbps.
> But does this standard have silence suppression?
>
> Thanks.
>
>



 
Reply With Quote
 
SG
Guest
Posts: n/a
 
      09-05-2003
Most voip device firmware will support VAD/silence deletion, otherwise,
plainly put, there's one less large reason for voip to exist.

"Alex" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Hi,
>
> I've read that G.711 doesnt compress voice data and operates at 64kbps.
> But does this standard have silence suppression?
>
> Thanks.
>
>
>



 
Reply With Quote
 
 
 
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Silence Detection MP3 Senger C++ 4 03-13-2006 01:08 PM
Silence detection Martin UK VOIP 3 02-04-2006 11:13 AM
Sipgate and Asterisk, Calls cut if silence detected Sparks UK VOIP 1 07-12-2005 09:03 AM
REVIEW: "Silence on the Wire", Michal Zalewski Rob Slade, doting grandpa of Ryan and Trevor Computer Security 1 06-27-2005 03:37 PM
DVD Verdict reviews: LOVING WALTER, THE PACT OF SILENCE, and more! DVD Verdict DVD Video 0 11-26-2003 10:04 AM



Advertisments