[SIPForum-discussion] Silence suppression attribute based onrfc3108

[Andro]

Hello,

I don't know if this answers your question, but I remember that , if annexb
support is not specified in SDP payload , it is enabled by default for g729.

Andrea

2009/7/6 Manpreet Singh <msingh at ibasis.net>

> Not sure if its still clear. 3389 talks about paylaod defition for CN.
> Its not touching the case where silencesuppression attribute is there or
> not. May be I am missing the text in the RFC so if someone can point me
> to exact excerpt, would be helpful. But my question is still not
> answered well in these rfcs. 3389 does say one needs to define the
> payload type to support CN. Absence of this doesn't mean no CN but RTP
> can still handle it via non-continous sequence numbers.
>
> The question really was if G729A or any other codec where Silence
> suppression is not ON by default, absence of silencesuppression attrbute
> in SDP means ON or OFF?  Ofcourse if one says ON then the SDP needs to
> define CN payload. But would that mean abesence of silencesuppression
> attribute means no VAD?
>
> Thnx
>
> -----Original Message-----
> From: John Atkinson [mailto:johnat at nortel.com]
> Sent: Wednesday, July 01, 2009 8:24 PM
> To: Anuradha Prakashkumar; Manpreet Singh; discussion at sipforum.org
> Subject: RE: [SIPForum-discussion] Silence suppression attribute based
> onrfc3108
>
> read RFC 3555 for 729AnnexB use  and 723annexA use
>
> and, as mentioned below, see rfc 3389 for codecs such as 711 and 726-32
> that don't have their own vad/cng/dtx algorithms
>
>
>
> -----Original Message-----
> From: discussion-bounces at sipforum.org
> [mailto:discussion-bounces at sipforum.org] On Behalf Of Prakashkumar,
> Anuradha WIPRO (External:WBNG:WIPRO)
> Sent: Wednesday, July 01, 2009 12:52 AM
> To: msingh at ibasis.net; discussion at sipforum.org
> Subject: Re: [SIPForum-discussion] Silence suppression attribute based
> onrfc3108
>
> RFC 3389? Have you checked? It talks lots about VAD and Noise level
> comfort. Also I could somewhere read it as endpoint implementation
> dependent. Will let you know if I get something more.
>
>
>
> ________________________________
>
> From: Manpreet Singh [mailto:msingh at ibasis.net]
> Sent: Wednesday, July 01, 2009 9:34 AM
> To: Anuradha Prakash kumar (WT01 - Telecom Equipment);
> discussion at sipforum.org
> Subject: RE: [SIPForum-discussion] Silence suppression attribute based
> on rfc3108
>
>
>
> Anuradha
>
>
>
> Thanks for the URL. Although it does say default is ON, its not writen
> in any spec. Is there a reference to spec you can point me to? Alteast
> 3108 doesnt talk about this and I am not sure where they are taking that
> reference.
>
>
>
> thnx
>
>
>
> ________________________________
>
> From: anuradha.kumar1 at wipro.com [mailto:anuradha.kumar1 at wipro.com]
> Sent: Tuesday, June 30, 2009 11:54 PM
> To: Manpreet Singh; discussion at sipforum.org
> Subject: RE: [SIPForum-discussion] Silence suppression attribute based
> on rfc3108
>
> Hello Manpreet,
>
>
>
> I had a chance to look at this. VAD or silence suppression is used to
> save bandwidth in a case where the originating and terminating parties
> do not speak but still the background voice gets played which is
> unnecessary.
>
>
>
> Now coming to your question whenever not indicated silence suppression
> or Voice Activity Detection is set to ON. I guess we can verify this as
> well by monitoring it by network analyzers like wire shark. Please refer
> to the URL
> https://lists.cs.columbia.edu/pipermail/sip-implementors/2006-January/01
> 1717.html<https://lists.cs.columbia.edu/pipermail/sip-implementors/2006-January/01%0A1717.html>
>
>
>
> Regards,
>
> Anu
>
> ________________________________
>
> From: discussion-bounces at sipforum.org
> [mailto:discussion-bounces at sipforum.org] On Behalf Of Manpreet Singh
> Sent: Tuesday, June 30, 2009 9:06 PM
> To: discussion at sipforum.org
> Subject: [SIPForum-discussion] Silence suppression attribute based on
> rfc3108
>
>
>
> Hi
>
>
>
> If the silence suppression attribute is not present in SDP, whats the
> default behaviour? Would the absence mean ON or OFF for a certain media
> type?
>
>
>
> thnx
>
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