this is mostly a logic problem, so i apologize for my question not
being cocoa specific.
i'm attempting to add my own continuous pitch variation effect
(vibrato) by assigning my sound's pitch to the path of a sine wave.
this is my callback method, which is repeating every 1/30 of a second.
- (void)vibratoCallBack:(NSTimer *)timer
{
float newPitch = 0.025 *
sin(kDegreesToRadians(vibratoDegreeIncrements));
self.pitch += newPitch;
vibratoDegreeIncrements += kVibratoDegreeIncrements; //this value is 45
}
the default pitch is set at 1.0, so the above outputs the following
sine wave cycle:
Wrong Pitch: 1.000000
Wrong Pitch: 1.017678
Wrong Pitch: 1.042678
Wrong Pitch: 1.060355
Wrong Pitch: 1.060355
Wrong Pitch: 1.042678
Wrong Pitch: 1.017678
Wrong Pitch: 1.000000
however, if you look at those numbers they are not much of a sine
wave. the reason, as far as i can see, is that self.pitch is adding
itself along with the sine wave increments. i would like the pitch to
be movable while the vibrato effect is happening, but i can't seem to
find a way. below is the proper sine wave output that i would like to
add to the current pitch:
Correct Pitch: 0.000000
Correct Pitch: 0.017678
Correct Pitch: 0.025000
Correct Pitch: 0.017678
Correct Pitch: 0.000000
Correct Pitch: -0.017678
Correct Pitch: -0.025000
Correct Pitch: -0.017678
Correct Pitch: -0.000000
therefore, if the pitch is at 1.0, i would like the output to look like this:
Desired Pitch: 1.000000
Desired Pitch: 1.017678
Desired Pitch: 1.025000
Desired Pitch: 1.017678
Desired Pitch: 1.000000
Desired Pitch: 0.917678
Desired Pitch: 0.925000
Desired Pitch: 0.917678
Desired Pitch: 1.000000
help would be greatly appreciated.
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