I have a page describing a very simple, very low-CPU low-pass filter that is also able to be framerate-independent. I use it for smoothing out user input and also for graphing frame rates often. http://phrogz.net/js/framerate-independent-low-pass-filter.html In short, in your update loop: // If you have a fixed frame rate smoothedValue += (newValue – smoothedValue) / … Read more
There is an Android class called Visualizer that lets you access audio being played http://developer.android.com/reference/android/media/audiofx/Visualizer.html In addition, since Android is all open source, you can look at how the live wallpaper does it! https://android.googlesource.com/platform/packages/wallpapers/MusicVisualization/
if you want angular frequency (w=2 pi f) to vary linearly with time then dw/dt = a and w = w0 + (wn-w0)*t/tn (where t goes from 0 to tn, w goes from w0 to wn). phase is the integral of that, so phase = w0 t + (wn-w0)*t^2/(2tn) (as oli says): void sweep(double f_start, … Read more
I was searching for a similar thing and decided to “roll my own.” I realize this is an old post, but in case anyone else is in search of this, here is my solution. it is relatively quick and dirty and normalizes the image to “full scale”. the images it creates are “wide” ie you … Read more