I'm working on a VST3 synthesizer. It has 8 Tone Generator Modules selectable from any of 10 engines, 8 Envelope Modules appliable to virtually all voice parameters, 8 Effect Module slots, 8 LFO Modules appliable to virtually all voice parameters, and many processor parameters, plus finally 8 Filter Modules each appliable to one or more tone generators. Each tone generator can be set to octave, semitone, or fine +/- pitch offset from norm as in middle A = 440Hz.
I have designed my synth so one sample is first gathered for each active tone generators. After that I apply modulation selectable by user, AM, RM, FM, PD, or PM.
Depended on the order you arrange carrier tone generator and modulation tone generator, a modulation tone generator can itself be modulation from another tone generator.
Anyways my implementation below, simplified to better illustrate my post question, works fine, however I don't know how, if even possible to fit in the Modulation Index.
As I understand it the modulation index is max carrier frequency deviation / modulator frequency, and the max carrier frequency deviation is carrier frequency * modulation level.
My tone generators, no matter what engine used, supply samples in the range of -1.0f to 1.0f.
So if for example the both the carrier and modulator's octave, semitone, and fine controls are set to '0', and I play a middle 'A', the frequency of both are 440Hz.
The max carrier frequency deviation would then be 440Hz * 2 (Multiply by 2 because a modulator sample is in the range from -1.0f to 1.0f, and I then add 1.0f later to adjust to 0.0f to 2.0f) * modLevel right?
If the above is correct, the Modulation Index would then be above result / modulation frequency (In this case 440Hz) right?
So if I calculated the Modulation Index right, how can I incorporate that into my above algorithm? Any advice, except to format my hard drive, is much appreciated, thanks!
I have designed my synth so one sample is first gathered for each active tone generators. After that I apply modulation selectable by user, AM, RM, FM, PD, or PM.
Depended on the order you arrange carrier tone generator and modulation tone generator, a modulation tone generator can itself be modulation from another tone generator.
Anyways my implementation below, simplified to better illustrate my post question, works fine, however I don't know how, if even possible to fit in the Modulation Index.
As I understand it the modulation index is max carrier frequency deviation / modulator frequency, and the max carrier frequency deviation is carrier frequency * modulation level.
My tone generators, no matter what engine used, supply samples in the range of -1.0f to 1.0f.
Code:
// FM Implementationfloat modulator = sampleValue[modSource];// I am below adding 1.0f to change the modulator * modLevel from -1 to 1, into 0 - 2.0// modLevel is in the range of 0 (no modulation), to 1 (max modulation)modulator = 1.0f + modulator * modLevel;// The modulator is now multiplied with the carrier tone generator's Delta, which is reset // to proper relation between note frequency, table size, and sample rate, before // the modulation code partdelta[carrier] *= modulator;// The above modified delta is then added to the carrier tone generator's phase variablephase[carrier] += delta[carrier];// Modulator tone generator's phase is also updatedphase [modSource] += delta[modSource];// And yes I check and adjust all tone generator's phase as needed when they go beyond // max phase, which for any engine is 2047, omitted here for simplicityThe max carrier frequency deviation would then be 440Hz * 2 (Multiply by 2 because a modulator sample is in the range from -1.0f to 1.0f, and I then add 1.0f later to adjust to 0.0f to 2.0f) * modLevel right?
If the above is correct, the Modulation Index would then be above result / modulation frequency (In this case 440Hz) right?
So if I calculated the Modulation Index right, how can I incorporate that into my above algorithm? Any advice, except to format my hard drive, is much appreciated, thanks!
Statistics: Posted by DKDiveDude — Thu Feb 22, 2024 7:04 pm — Replies 0 — Views 28