[Asterisk-Dev] G.722

[Steve Underwood]

Andrew Lindh wrote:

>G.722 (original version) code can be found at:
>ftp://ftp.cs.cmu.edu/project/speech/speech-compression/CCITT-ADPCM/64kbps/adpcm6
>4_g722_efficient
>
>
>It has the notice:
>The program is available by ftp from CMU, and may be used and distributed
>freely, provided the copyright notices are maintained.
> 
>The Carnegie Mellon ADPCM program is Copyright (c) 1993
>by Carnegie Mellon University. Use of this program, for any research or
>commercial purpose, is completely unrestricted.  If you make use of or
>redistribute this material, we would appreciate acknowlegement of its origin.
>
>
>There is also some older code (from ITU?) with no notice of ownership.
>
>
>
>  
>
>>Date: Sun, 19 Dec 2004 21:42:43 -0500
>>From: Dorn Hetzel <asterisk at dorn.hetzel.org>
>>To: Andrew Lindh <asterisk at ntplx.net>, Asterisk Developers Mailing List 
>>    
>>
><asterisk-dev at lists.digium.com>
>  
>
>>Subject: Re: [Asterisk-Dev] 16 KHz audio ?
>>
>>On Fri, Dec 17, 2004 at 05:15:24PM -0500, Andrew Lindh wrote:
>>    
>>
>>>Here are some other G.722 versions:
>>>
>>>Codec	ITU yr	type		delay	rate
>>>G.722	1988	SB-ADPCM	2ms	48 56 64k
>>>G.722.1	1999	Transform?	20ms	24 32k
>>>G.722.2	2002	ACELP		20ms	23.85 down to 6.6k
>>>
>>>G.722.2 is also known as AMR-WB which looks good on paper. But again
>>>the patent pool has a deep end and it's not cheap...
>>>
>>>While G.722 may be free and easy it is not the advanced codec that
>>>most people will be looking for. G.722 and it's additions are
>>>rather different from each other, I don't know what the phones
>>>support today. They may support only newer versions.
>>>
>>>      
>>>
>>I think Grandtream does the old G.722, at least from what
>>the bit rate seems implied to be...  I don't mind 64K, I
>>use G.711 now, so it would be no more bits and better sound :)
>>
>>-Dorn
>>    
>>
I saw G.722 running in 1987, so any patents could only still exist in 
the US. However, I don't think there ever were any. G.722 was intended 
to replace G.711 as ISDN became widespread :-) It certainly offers 
better quality at the same bit rate as G.711. It is still better when 
you run it at 48kbps. It never seemed like a brilliant design, though.

I think most people doing VoIP consider 48kbps rather high, even if much 
of what they send is just RTP overheads :-) Modern codecs achieve better 
quality at half that bit rate, but most are encumbered. G.722.2 seems 
almost certain to become widespread, as it is one of the UMTS 3G codecs. 
Its pretty heavily encumbered, though.

This might be a real chance for speex to catch on. There are no wideband 
codecs that are particularly widely deployed. Speex has a nice wideband 
mode, at a modest bit rate, and little installed base to push it to the 
sidelines.

Regards,
Steve