Hello, Yes I have thought about such a mode "audio morse code" that will punch through some sort of voice signal. I think the theoretical limit for human speech is about 50 bit/s (i.e. text-speech).
The LSPs are where most of the bits are used, so you could test a low bit rate vector quantiser. I think some one posted some results to this list doing just that a few months ago The other approach is to have a large delay (a second) and use this delay to remove more redundancy. Cheers, David On Wed, 2012-02-01 at 15:10 -0700, Steve Strobel wrote: > I think it is impressive how natural-sounding codec2 is even at > 1400bps. I am considering a potential application that would be > practical only if the bandwidth was a small fraction of even that. It > wouldn't be important that the audio sound natural, but it would need > to be intelligible. I would like to try reducing the number of bits > used for each field in an effort to see how much the bandwidth could > be reduced and still provide speech that could be understood. I > suppose in the extreme case, the pitch field could be eliminated > altogether, resulting in monotone output. Some of the other fields > could surely also be reduced somewhat. > > If any of you that have worked with codec2 could give me a suggestion > about where to focus my efforts, that would be great. Any wild > guesses about how far the bandwidth could be reduced and still produce > intelligible speech? (I realize that intelligibility is highly > subjective). Thanks. > > Steve > > ------------------------------------------------------------------------------ Keep Your Developer Skills Current with LearnDevNow! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnow-d2d _______________________________________________ Freetel-codec2 mailing list Freetel-codec2@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freetel-codec2
