On Fri, 06 Mar 2009 02:15:12 +0800, Steve Underwood wrote: >Steve Underwood wrote: >> They might be doing some kind of fake bandwidth expansion. You can't >> create something out of nothing, and make the narrowband voice more >> intelligible, but you can make it sound pretty nice. Jean-Marc Valin (he >> of speex fame) has a very impressive expander he is working on at the >> moment. >> >Someone tells me Polycom definitely do some form of bandwidth expansion, >though its a lot less realistic than Jean-Marc technique.
What do you mean by "bandwidth expansion?" The term expansion in audio is most commonly used in reference to dynamic range. Expanders (and their inverse, compressors) vary the level of a signal dynamically to effect changed signal.noise ratio. How does one effect frequency domain extension? That seems counterintuitive to me. Frequency response (pass-band) is a function of sampling rate (see Nyquist) and anti-aliasing filtering. Michael -- Michael Graves mgraves<at>mstvp.com http://blog.mgraves.org o713-861-4005 c713-201-1262 sip:[email protected] skype mjgraves fwd 54245 _______________________________________________ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
