Eric Bart wrote:
Please read this skype experience:
http://www.vonage-forum.com/article312.html
Isn't marketing material wonderful? :-)
Oops. Is Vonage now selling Skype ?
Whatever. I've tested Skype. I'm telling it's HiFi !!!
Skype may be using a 24 KHz bandwidth. I know that they're also using
a very good compression codec.
I think 24kbps is rather more likely than 24kHz bandwidth :-)
No. I read in a forum that someone saw that Skype was opening a sound card
driver at 48KHz. Why would it if not for using it ?
They do that because few sound cards can sample at 16k/second. They use
48k/second and rate convert in software. The codec isn't using 24kHz
bandwidth.
It's not because you're sampling at 48K that you'll get a huge output rate.
It depends on the codec efficiency.
Duh! yeah!
Skype uses iLBC.
It's using some globalipsound technology.
http://www.globalipsound.com/customers_partners/customers_partners.php
http://www.globalipsound.com/solutions/solutions_Codecs.php
That's iLBC
I think the wideband version of iLBC is 24kbps.
On my PC I have 4 DivX audio codecs for 44KHz : 32, 22, 20 and 16 Kbps
Many things are possible, with variably crappy results. Actually, it
doesn't take many extra bits to code the higher frequencies. The bulk of
the bits concentrate on the first 4kHz.
I'm sure it's possible to get a streaming 24KHz bdwdth in 24kbps. However
maybe it's not available for a gnu software.
The wideband iLBC isn't available for royalty free use, as far as I
know. They only allow the narrowband to be used in that way.
Regards,
Steve
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