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Old 03 December 2013, 18:24   #50
Precious & fragile things

Join Date: Feb 2009
Location: Victoria, Australia
Posts: 1,927
Originally Posted by mc6809e View Post
There's plenty of sound generation hardware. DACs, PWM volume control, mixing voices together to form a stereo pair, pitch control registers, FM and AM modulation options -- this is all part of the sound generation hardware.

The only thing not in hardware is the waveform itself -- and that's a good thing!

A sample is a measurement of a signal. If the waveform comes from measuring a signal and storing samples into a memory then that's sample-based synthesis. If that waveform is derived analytically, then it isn't a sample. It's another form of synthesis -- wavetable synthesis.
Wavetables have been discussed earlier in the thread and whilst it is seen as its own synthesis method it's still sample based. AM involves adjusting the value of the currently played sample value either up or down by amount x and is therefore computed, FM adjusts the speed register up or down by amount y and is therefore computed. PWM isn't used, volume control is just a value in a register which adjusts an internal amp to Paula I would suppose and mixing voices together would be done post DAC with a mixing amplifier. Not one single element of this is sound generation but sound manipulation, effects and nothing more. To have sound generation you need an oscillator and there aren't any.

A sample is made using an ADC to transfer values to ram over time. The only difference in the Amiga is that you are putting the values into ram, skipping the ADC but doing exactly the same thing. Sampling refers to this technique but the remains in ram is the sample itself.
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