[Asterisk-Dev] H323 Channel Driver

[Bruce Ferrell]

Hi Ben,

I've been told that transcoding is hellish to do.  I'd LOVE to see that 
proved wrong.  Go dude! go!

Ben Lear wrote:
> Hi all,
> 
> It has been quite a while (almost a year :| ) since I first played
> around with Asterisk H323 channel drivers. A current project requires
> such functionality and thus I have a rekindled interest. During my time
> away the Asterisk and openH323 libraries have changed considerably and
> the modified Inaccess H323 channel driver which I had working near
> perfectly... no longer even compiles :(  Which is a shame as it
> supported *ALL* the H323 CODECS made available by openh323, not just
> A-Law, U-Law and sort of GSM.
> 
> Checking around today I see there are now two implementations, the
> original Inaccess(pseudo soundcard version) and "Pingtel"(Native
> Asterisk RTP Stack version). Now, I got both of these to work (with some
> tweaking) but where back to A-Law, U-Law and GSM (sort of) which is just
> tragic :( 
> 
> So now the question/proposal.... My idea to quickly get both/one of
> these drivers working with all of the H323 codecs (all with DTMF etc)
> was to implement a conversion layer at some point in the audio path. The
> idea being that we pick something Asterisk can work with, lets say
> u-Law, so the H323 driver *always* talks to Asterisk using u-Law and a
> "bridge" feeds the H323 client. Something like dis:
> 
> [CLIENT] <-> [CONNECTION] <-> [CODEC BRIDGE] <-> [ASTERISK]
> 
> Looking into at some possible implementation points it seems fairly
> straight forward to do. I know I would be copping a encode/decode CPU
> overhead but I care not (hardware is cheap). This could be a bridging
> solution in itself until Asterisk supports the required native H323
> codecs / functions and a "nicer" driver can be molded, at such time this
> could be slotted into existing applications that use the "bridge" driver
> with zero reconfig; it should just work :)
> 
> Anyways, I just thought I would throw this at the list to see if anyone
> has some already done this or has some comments before I start coding.
> 
> Let the flaming begin :P
> 
> Cheers,
> 
> Ben.
> 
> 
> 
> 
> 
> 
> 
> 
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