I really don't know who else to ask or where else to look.
I REALLY REALLY need source code for: time-domain/frequency-domain DIGITAL FILTER. I have scanned the NET, looked through some books, but all have produced no source code I can use. I want code which can except the NEW frequency magnitude (any frequency/frequencies) and begin filtering the digital sound data to RECREATE the new digital sound data reflecting "exactly" the desired new frequency magnitude.
What I am doing is taking in 16-bit digital sound data, applying an FFT to it to get the sound's frequency spectrum (power spectrum). What I want to do with this "spectrograph" display is to EDIT the magnitudes to my liking (any frequency to any magnitude). Once I have the desired looking spectrograph, I apply an Inverse FFT on the spectrograph to get the NEW 16-bit digital sound data. The only thing is, I've heard that if I want to do this, I MUST USE a digital filter and to not directly edit the magnitudes and do Inverse FFT. So to get a proper 16-bit digital output data, I must go INPUT 16-bit digital data --> FFT --> We get SPECTROGRAPH --> Edit spectrograph to liking --> Apply Inverse FFT to NEW spectrograph --> We finally get NEW 16-bit digital data.
Please, if you have code which can do this for me or know where to obtain such code, I would love to get a hold of it from you! Any help you can provide would be GREATLY APPRECIATED!!