> wouldn't it be easier to check for zerocrossings? This would assume a perfect sine wave for both tones. The bad thing about zero crossing is that even the tiniest amount of noise completely ruins it, and then you're looking at second derivatives, which are also dependent upon signal quality. The great thing about dtmf, is you can find the signal even in truly bad cases.
An alternative to an fft is parallel resonant filters, but you cannot then check non-dtmf frequencies to avoid false triggering. FFTW is the way to go. Tony ------------------------------------------------------- This sf.net email is sponsored by: Jabber - The world's fastest growing real-time communications platform! Don't just IM. Build it in! http://www.jabber.com/osdn/xim _______________________________________________ Alsa-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/alsa-devel
