Bruce- > > We've been working on a new lowlatency codec for speech and music, > > CELT, and are about to public a paper on it. (celt-codec.org). > > While CELT wouldn't be useful for narrowbanded voice some of the > > components of CELT would be very useful in an AMBE killer. > > (Particularly CWRS, the algebraic vector quantizer). CELT itself > > could be used for a 10-20khz wide mode (40-60kbit/sec with decent SNR) > > to replace FM with something with much greater quality if there was > > interest... But a lower bandwidth mode will be far more interesting. > > > Would this be useful to solve the garble problem when there's a > firefighter with a loud chainsaw in the background? That just kills the > codecs they use on APCO 25 right now.
If the codec can handle music and other audio signals besides speech, then the answer is probably yes. That would mean the codec uses "perceptual" techniques, which are general, rather than specific technique based on a human vocal tract model. The vocal tract model is what gets codecs like AMBE and MELPe into trouble when they encounter non-speech sounds. MP3 uses perceptual techniques. But like Gregory said, lower bandwidth operation is key. Without that codecs like will AMBE persist. MELPe goes as low as 600 bps. Essentially they accomplish this by making a wide range of assumptions based on speech-like signals. -Jeff _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio