[Asterisk-Dev] Channels, jitterbuffer and PLC?

[Steve Kann]

Bob Carlson wrote:

>I am implementing a new channel module and just ran into a probable
>misunderstanding on my part. Could someone check my understanding here?
>
>My channel will be receiving SLINEAR only and the calls will be terminated
>on the other side of * by a SIP channel (chan_sip) running a-law or u-law.
>Thus the core will be delivering me packets in SLINEAR that have been
>processed from RTP/a- or u-law. I will be feeding the SLINEAR to a TDM bus.
>
>
>I had been under the impression that the core would be doing (or could be
>told to do) jitter buffering and PLC. The channel modules I based mine on,
>did not contain any code for these functions.  I have read several threads
>on the new jitter buffer code and looked at some other channel code, like
>IAX2 and it now appears to me that any channel needing JB and PLC must
>implement them itself. Is that correct?
>
>And the next question: is the new jitter buffer code easily integrated into
>other channels like mine, so I don't have to re-invent the wheel?
>  
>
Yes, pretty easily for the JB.

The one problem you'll find for a full implementation is that presently, 
PLC only takes place upon translation from someformat -> slinear, and 
not the other way around, but if you only take slinear in, then you 
could do the PLC yourself (also, that's not too hard).

But, now that I read your query again, this isn't what you want at all: 
If your side is TDM, you don't want a jitterbuffer there. You want the 
jitterbuffer on the receive side of the VoIP channels. So, assuming that 
RTP/chan_sip gets the jitterbuffer, and you're taking in slinear, it 
should all be good for you with no knowledge of the jitterbuffer or PLC 
going on.

-SteveK


-SteveK