Re: [payload] draft-ramalho-payload-g7110-00 to be discussed inAVTEXT

["Kevin P. Fleming" <[e-mail]>]

On 07/26/2011 01:51 PM, Hadriel Kaplan wrote:

>> The suggested "hint" in the G.711 SDP is not to "signal G.711.0", but
>> rather for middleboxes like NATs/Firewalls/etc. to "expect G.711" in
>> either uncompressed (real G.711 with PT = [0 | 8]) or compressed (with
>> PT = Q) form as equivalents.
>
> But they're NOT equivalent.  For all intents and purposes G.711.0 is a different codec from G.711, afaict.  That it can be implemented as a bump-in-the-wire without full DSPs matters not.  The most logical thing for a middlebox to do would be to handle it exactly like it handles middlebox-provided transcoding/transrating cases today, with normal SDP modifications/behavior, no? (and by that I mean act as a first-class participant in SDP, by inserting/adding codecs into the same m-line, and handling offer/answer appropriately)

I tend to agree with Hadriel's opinion here; this really isn't much 
different from a pair of middleboxes in the path of a G.711 call 
choosing to transcode the audio stream to/from G.729 in order to save 
bandwidth (except that does require DSP-type processing, but that 
shouldn't affect how the transformation is signaled).

-- 
Kevin P. Fleming
Digium, Inc. | Director of Software Technologies
Jabber: [e-mail] | SIP: [e-mail] | Skype: kpfleming
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
Check us out at www.digium.com & www.asterisk.org