I just published a guitar tune app myself (Guitar FreaQ)...mostly for fun and to teach myself android development.
I found that the FFT didn't use that much cpu at all (custom rendering did though) The fft algorithm computes N log(N) calculations. So if you do a 1024 point fft you are only doing 1024*10 calculations per pass. If you do a straight DFT computation per string and compare you will do 1024 calculations per string or 1024*6. For me, the additional 1024*4 calculations was worth the extra robustness. On Fri, Nov 19, 2010 at 6:16 PM, Chris Stratton <[email protected]> wrote: > On Oct 26, 11:45 am, Bret Foreman <[email protected]> wrote: > > > As a first cut I would set up two files, record to one while doing an > > FFT on the other. Alternate the roles of the files every 200mS and > > display the latest frequency. Do you have experience with FFT > > windowing to avoid edge harmonics? > > If you don't know what string is being played and need to determine > it, an FFT could make sense. > > Since you only have 6 (or 12?) strings to check, you could avoid the > windowing by calculating a single point of the DFT of a length > optimized for each string's frequency, normalizing, and comparing them > to determine which is being played. > > Once you do know the string, an FM demodulator algorithm centered at > the proper frequency might be a superior approach for determining the > tuning error. > > -- > You received this message because you are subscribed to the Google > Groups "Android Developers" group. > To post to this group, send email to [email protected] > To unsubscribe from this group, send email to > [email protected]<android-developers%[email protected]> > For more options, visit this group at > http://groups.google.com/group/android-developers?hl=en > -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
