Re: Selection of media (m=) at MG

 
> 2º In case that codec may not be used (for an error, for 
> example), the 
> second codec would be tried (I understand this is the reaseon why the 
> Remote descriptor may have several audio codecs in the same line "m=).
> 
> 
> If it is so, and we use:
> 
>   m=audio<puerto>   RTP/AVP 0 [8]<PT_dinámico>   
> 
> 
> What would happen if when MG needs to send the tone/annc., the 
> codecs "0" 
> and "8" may not be used?. MG would try to send the tone/annc. to the 
> terminal using CLEARMODE, when terminal is not ready to receive that.

The codec used on IP term side do not impact the data format sent on ISDN term.
(but it impacts the content due to use of lossy or lossless codec on IP).

CLEARMODE only tells the GW to turn off any encoding/decoding/echo-cancellation/DTMF etc.
and send the received data as is on either side. 

In fact, when a signal (tone/annc) is played on one termination (signal going outside of the context),
the termination is temporarily "disconnected oneway" (so it won't receive any data, but can send) from 
the other terminations (as if the termination has "oneway" topology to others).

-Raju


> -----Original Message-----
> From: [email protected] 
> [mailto:[email protected]] On Behalf Of Javi Muñoz
> Sent: Thursday, December 01, 2011 12:43 PM
> To: [email protected]
> Cc: Bhattacharjee, Arindam (Arindam)
> Subject: Re: [Megaco] Selection of media (m=) at MG
> 
> Arindam,
> 
> > You can use another option: have reserve value on and use 
> both g711 and Clearmode on both remote and local SDP and MG 
> will send in g711 only because that has higher preference 
> when G711 appears before CLearMode codec in the list as follows:
> >
> >   m=audio<puerto>   RTP/AVP 0 [8]<PT_dinámico>
> >   a=rtpmap:<PT_dinámico>   CLEARMODE/8000
> 
> When the Remote descriptor has several audio codecs in the line "m=":
> 
>   m=audio<puerto>   RTP/AVP 0 [8]<PT_dinámico>   
> 
> 
> I understand that:
> 
> 1º First codec in the line is used if it is possible.
> 
> 2º In case that codec may not be used (for an error, for 
> example), the 
> second codec would be tried (I understand this is the reaseon why the 
> Remote descriptor may have several audio codecs in the same line "m=).
> 
> 
> If it is so, and we use:
> 
>   m=audio<puerto>   RTP/AVP 0 [8]<PT_dinámico>   
> 
> 
> What would happen if when MG needs to send the tone/ann., the 
> codecs "0" 
> and "8" may not be used?. MG would try to send the tone/ann. to the 
> terminal using CLEARMODE, when terminal is not ready to receive that.
> 
> Javi
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