frequency

I need to use Band Pass Filter to filter my real time recording audio. The Range is about 18Khz to 22Khz. I've seen many examples,unfortunatly they are used to detect frequency of audio....Since i'm new to DSP,please ellobrate your answer.... 来源： https://stackoverflow.com/questions/21456630/how-to-use-band-pass-filter18khz-to-22khz-in-android

I want to plot the frequency spectrum of a music file (like they do for example in Audacity). Hence I want the frequency in Hertz on the x-axis and the amplitude (or desibel) on the y-axis. I devide the song (about 20 million samples) into blocks of 4096 samples at a time. These blocks will result in 2049 (N/2 + 1) complex numbers (sine and cosine -> real and imaginary part). So now I have these thousands of individual 2049-arrays, how do I combine them? Lets say I do the FFT 5000 times resulting in 5000 2049-arrays of complex numbers. Do I plus all the values of the 5000 arrays and then take

I have a sound file (.3gp) and its about ~1 min. I would like to get the frequency of this sound file in every 1/4 seconds. My idea is to receive samples in every 1/4 seconds from the audio file and using FFT I might get the frequency values. Is there any way to do this? Actually I would split the sound file into 1/4sec samples sound files (alwyas overwriting the preveious one), then using FFT algorithm and detect the frequency where the magintude is the bigggest. But there might be easier solutions however I dont have a clue how to do this either. ***UPDATE 2 - new code I use this code so far