On Sun, Jun 26, 2011 at 10:44:33AM +0200, [email protected] wrote:
> I think you understood what I am looking for below. Unfortunately, I can only guess what the context of your question was, and I'd probably be wrong :-( > Does anyone have a code example for this type of filter? The example Erik gave is a perfect one. As said, there's no such thing as 'the phase of a waveform'. For a general waveform, and no matter what interpretation of 'phase' you'd choose, it would be a function of frequency. If the waveform is cyclic (e.g. a triangle wave) you could define some 'phase' value on it, using either the fundamental frequency or some arbitrary point in the waveform as reference. But even for a simple sine wave the term 'phase' can mean different things. Take s(t) = sin (w * t + phi), with w = 2 * pi * f All the following are correct: (1) If you take 'phase' as a property of s(t) as a whole, you could say its phase is phi. (2) If look at absolute phase at time t, it would be w * t + phi. (3) If you use t = 0 as a phase reference point, the phase at time t would be w * t. It all depends on the context which one you use. To add some more ambiguity, compare s1(t) = sin (w * t + phi) s2(t) = cos (w * t + phi) In many cases it doesn't matter which one you use when defining or explaining something. If you have a maths background you'd prefer cos() for real signals, since that's the real part of the complex single frequency signal exp(j * (w * t + phi)). If you are defining e.g. a oscillator opcode in a synthesis system you'd prefer sin(), as this starts at zero for phi = 0. In both cases you could legitimately refer to 'phi' as 'the phase'. But the two waveforms are 90 degrees out of phase w.r.t. each other... Ciao, -- FA _______________________________________________ Linux-audio-dev mailing list [email protected] http://lists.linuxaudio.org/listinfo/linux-audio-dev
