Class notes 1/15: modulating signals, time & computers

For controlling volume, use numbers between 0 and 128 (max volume).

Shift key allows you to make multiple connections at once.

If sound is too soft, how do we figure out the multiplier to get it to the correct volume?  In Audacity, there's a normalization function that fixes things.

loadmess~  When the patcher loads, send out this (short) message.

live.gain~   Slider that scales volume for moderate loudness, shows dB of output.

Modulating one signal by another:
This is why you'd scale a signal to a smaller amplitude and then use an add function to push it up towards +1.  It can be used to modulate the amplitude of another signal, say a cycle~ 440, to create tremolo (and eventually other effects).  Send the modulating signal into a multiplier and then to the signal you want to modulate.  If you send it directly into the frequency you want to modulate (the cycle~), it will create vibrato (pitch variation) instead.

Modulating signal can be amplified by a lot (times 12, for example), to change "depth" of modulating oscillator.  (Think of that as the amount of the modulator's effect.)

If you bring modulating signal really wide and up in frequency into audio range, can get whole host of strange harmonics.


Time:
CPU clock, crystal vibrating at known frequency installed in each computer--each vibration allows circuit(s) to be closed and opened.
CPU speed is like 2.4 GHz now, it's really fast.
Computer tries to do tasks you give it as fast as possible.  What if you want a computer to do something at a slower, pre-determined rate?

metro~  Outputs a bang message at regular intervals.  (Time expressed in milliseconds.)  Right inlet can be connected to number box that will change intervals.  If you want to set a tempo of beats per minute, use !/~ to divide bpm into 60,000 and will calculate how many ms between beats for you.

counter~  Counts the number of times something has happened--output left outlet to select~ 7 (or whatever number) and output select 7 to a zero message to tell it to stop after that.  *It starts counting at zero, so saying select 7 will stop it after 8 times.