[Asterisk-Users] VAD/DTX implementation through zaptel cards

[Eric Wieling]

No.

parijat wrote:

> Pls could u be more elaborate as I am new to asterisk..
> 
> -----Original Message-----
> From: asterisk-users-bounces at lists.digium.com
> [mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Eric Wieling
> Sent: Wednesday, April 13, 2005 7:37 PM
> To: Asterisk Users Mailing List - Non-Commercial Discussion
> Subject: Re: [Asterisk-Users] VAD/DTX implementation through zaptel cards
> 
> The only time PLC makes sense is thwn you are converting FROM VoIP to 
> something else.  So PLC would be done on chan_sip or chan_IAX, or 
> chan_h323 on the receiving end.  This is for 1.0.x.
> 
> For CVS-HEAD you would want to do this on the receiving side in the 
> PLC stuff.
> 
> parijat wrote:
> 
> 
>>Hi,
>>Thanks for helping me out.
>>
>>I want to clear out few more points
>>
>>1) zaptel cards receive PCM from PSTN. In what form do they give it to
>>asterisk. Do Zaptel cards CODE/DECODE PCM from PSTN to RTP or zaptel cards
>>forward PCM to asterisk which converts it to RTP.
>>
>>2) If asterisk does that conversion then, using which file 
>>does it convert. I want to change code of that file so that I can
> 
> implement
> 
>>VAD.  
>>
>>3) If all this is not possible then why they have give so many codec files
>>in asterisk.
>>
>>Regards,
>>Parijat
>>
>>-----Original Message-----
>>From: asterisk-users-bounces at lists.digium.com
>>[mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Steve
>>Underwood
>>Sent: Tuesday, April 12, 2005 9:40 PM
>>To: Asterisk Users Mailing List - Non-Commercial Discussion
>>Subject: Re: [Asterisk-Users] VAD/DTX implementation through zaptel cards
>>
>>Steve Kann wrote:
>>
>>
>>
>>>Eric Wieling wrote:
>>>
>>>
>>>
>>>>parijat at varaha.com wrote:
>>>>
>>>>
>>>>
>>>>>Hi,
>>>>>How can i implement VAD/DTX using zaptel with asterisk towards PSTN. 
>>>>
>>>>
>>>>
>>>>TDM (PSTN/telcos) do not support VAD. The entire idea of VAD is not 
>>>>even a valid idea.
>>>
>>>
>>>Doing VAD on audio coming _from_ the TDM world certainly is something 
>>>you might want to do, to dramatically reduce the bandwidth you consume 
>>>when sending the audio via VoIP channels.
>>>
>>>This kind of thing is not presently implemented in *, though, but it 
>>>could be. (note: doing it well will require a bunch of CPU, though. I 
>>>wonder if it could be done in the same DSP that is doing 
>>>echo-cancellation on the new TE4xxP boards?
>>
>>
>>Unless Digium's plans changed since the last time I spoke to Mark, the 
>>answer would be no. I believe they are using a dedicated function echo 
>>canceller device.
> 
> 
> 


-- 
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