[Asterisk-Dev] 16 KHz audio ?

[Steve Underwood]

Andrew Lindh wrote:

>G.722 (wideband speech coding standard) would be a good step.
>It's an accepted standard and some phones already support it.
>It should not be too hard to write a new codec/format module
>for asterisk. Looks like it only needs about 10MIPS of power to
>run. I'm sure there is already some reference code out there.
>I don't know the copyright/patent status of the code of G.722
>
>One of the benefits from this would be to improve communication
>between people speaking English where English is NOT their first
>language. It's hard enough to speak someone else's language
>but when both parties are using non-native speech you need all
>the help you can get....if you have the bandwidth for 64K....
>
>FYI: G.722 is a 14 bit 16Khz sampled with SB-ADPCM compression
>down to 64K, 56K, or 48K.
>
>http://www.itu.int/rec/recommendation.asp?type=folders&lang=e&parent=T-REC-G.722
>  
>
That is the obsolete G.722 It is too old to have patent protection, but 
too nasty to be interesting. It was part of the original definition of 
ISDN, and was supposed to be the PSTN's path to an all 7.1kHz bandwidth 
future. It never happened. The 10MIPs figure is for a DSP chip. It is 
probably 50-60MIPs on a Pentium (just an educated guess).

G.722.1 is the current standard, but it is recent and patented (i.e. the 
patents will not expire any time soon).

Regards,
Steve