;Written by Iain McCurdy, 2006 -+rtaudio=PortAudio -b4096 sr = 44100 kr = 4410 ksmps = 10 nchnls = 2 ;FLTK INTERFACE CODE;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; LABEL | WIDTH | HEIGHT | X | Y FLpanel "FM Synthesis: Simple Carrier->Modulator", 500, 220, 0, 0 ; ON | OFF | TYPE | WIDTH | HEIGHT | X | Y | OPCODE | INS | STARTTIM | IDUR gkOnOff,ihOnOff FLbutton "On/Off", 1, -1, 2, 150, 28, 0, 0, 0, 1, 0, 3600 ;VALUE DISPLAY BOXES WIDTH | HEIGHT | X | Y idModAmp FLvalue " ", 60, 20, 0, 80 idCarrAmp FLvalue " ", 60, 20, 0, 130 ; MIN | MAX | EXP | TYPE | DISP | WIDTH | HEIGHT | X | Y gkModAmp,ihModAmp FLslider "Modulator Amplitude", 0, 20000, 0, 5, idModAmp, 500, 30, 0, 50 gkCarrAmp,ihCarrAmp FLslider "Carrier Amplitude", 0, 20000, 0, 5, idCarrAmp, 500, 30, 0, 100 ; MIN | MAX | STEP | TYPE | WIDTH | HEIGHT | X | Y gkModFreq, ihModFreq FLtext "Modulator Frequency", 0, 20000, .5, 1, 100, 20, 50, 150 gkCarrFreq, ihCarrFreq FLtext "Carrier Frequency", 0, 20000, .5, 1, 100, 20, 350, 150 FLsetVal_i 1000, ihModAmp FLsetVal_i 10000, ihCarrAmp FLsetVal_i 200, ihModFreq FLsetVal_i 200, ihCarrFreq FLpanel_end ;INSTRUCTIONS AND INFO PANEL FLpanel " ", 515, 700, 512, 0 FLscroll 515, 700, 0, 0 ;TEXT BOXES TYPE | FONT | SIZE | WIDTH | HEIGHT | X | Y ih FLbox " FM Synthesis: Simple Modulator->Carrier ", 1, 5, 14, 490, 15, 5, 0 ih FLbox "-------------------------------------------------------------", 1, 5, 14, 490, 15, 5, 20 ih FLbox "This example demonstrate FM (frequency modulation) synthesis ", 1, 5, 14, 490, 15, 5, 40 ih FLbox "in its simplest form. Two oscillators are used (one will be ", 1, 5, 14, 490, 15, 5, 60 ih FLbox "referred to as the 'carrier' and the other as the ", 1, 5, 14, 490, 15, 5, 80 ih FLbox "'modulator'). ", 1, 5, 14, 490, 15, 5, 100 ih FLbox "Both oscillators employ a sine wave shape (as is most often ", 1, 5, 14, 490, 15, 5, 120 ih FLbox "the case in FM synthesis). ", 1, 5, 14, 490, 15, 5, 140 ih FLbox "The frequency (pitch) of the carrier is modulated (through ", 1, 5, 14, 490, 15, 5, 160 ih FLbox "addition) by the audio output of the modulator. ", 1, 5, 14, 490, 15, 5, 180 ih FLbox "Only the audio output of the carrier will be present at the ", 1, 5, 14, 490, 15, 5, 200 ih FLbox "final audio outputs of the FM synthesis algorithm. (The ", 1, 5, 14, 490, 15, 5, 220 ih FLbox "modulator is heard indirectly through its influence upon the ", 1, 5, 14, 490, 15, 5, 240 ih FLbox "frequency of the carrier.) ", 1, 5, 14, 490, 15, 5, 260 ih FLbox "In this example the user is given direct control over the ", 1, 5, 14, 490, 15, 5, 280 ih FLbox "amplitudes and frequencies of the modulator and carrier ", 1, 5, 14, 490, 15, 5, 300 ih FLbox "oscillators. This is not necessarily the most useful design ", 1, 5, 14, 490, 15, 5, 320 ih FLbox "for FM synthesis but should give you the clearest idea of how", 1, 5, 14, 490, 15, 5, 340 ih FLbox "the modulator and carrier interact. ", 1, 5, 14, 490, 15, 5, 360 ih FLbox "First of all adjust the carrier amplitude. Notice how this ", 1, 5, 14, 490, 15, 5, 380 ih FLbox "functions as a simple volume control. It has no effect on ", 1, 5, 14, 490, 15, 5, 400 ih FLbox "timbre. ", 1, 5, 14, 490, 15, 5, 420 ih FLbox "Next adjust the modulator amplitude. Notice how this varies ", 1, 5, 14, 490, 15, 5, 440 ih FLbox "the brightness or spectral intensity of the sound. When this ", 1, 5, 14, 490, 15, 5, 460 ih FLbox "is set at zero we are left with a pure sine tone (not ", 1, 5, 14, 490, 15, 5, 480 ih FLbox "silence!). ", 1, 5, 14, 490, 15, 5, 500 ih FLbox "When we vary the modulator and carrier frequencies this ", 1, 5, 14, 490, 15, 5, 520 ih FLbox "changes the nature of the timbre. (These parameters are ", 1, 5, 14, 490, 15, 5, 540 ih FLbox "adjusted by either clicking and dragging left and right on ", 1, 5, 14, 490, 15, 5, 560 ih FLbox "the values displayed or by clicking a cursor into the box ", 1, 5, 14, 490, 15, 5, 580 ih FLbox "and typing in a new value.) ", 1, 5, 14, 490, 15, 5, 600 ih FLbox "Notice how when the modulator and carrier frequencies are in ", 1, 5, 14, 490, 15, 5, 620 ih FLbox "simple ratio with one another harmonic spectra are produced. ", 1, 5, 14, 490, 15, 5, 640 ih FLbox "For example when M.F. (modulator frequency) is 300 Hz and ", 1, 5, 14, 490, 15, 5, 660 ih FLbox "when C.F. (carrier frequency) is 200. ", 1, 5, 14, 490, 15, 5, 680 ih FLbox "Notice how when M.F. and C.F. are not in simple ratio with ", 1, 5, 14, 490, 15, 5, 700 ih FLbox "one another inharmonic spectra are produced. For example when", 1, 5, 14, 490, 15, 5, 720 ih FLbox "M.F. is 277 and C.F. is 200. ", 1, 5, 14, 490, 15, 5, 740 ih FLbox "Notice how when one frequency is slowly detuned away from a ", 1, 5, 14, 490, 15, 5, 760 ih FLbox "simple ratio with respect to the other a kind of timbral ", 1, 5, 14, 490, 15, 5, 780 ih FLbox "'beating' is heard. As the amount of detuning increases the ", 1, 5, 14, 490, 15, 5, 800 ih FLbox "rate of beating increases until it is no longer perceivable. ", 1, 5, 14, 490, 15, 5, 820 ih FLbox "In general the modulator amplitude should be quite low in ", 1, 5, 14, 490, 15, 5, 840 ih FLbox "order to produce more interesting timbres that are not ", 1, 5, 14, 490, 15, 5, 860 ih FLbox "excessively shrill. As M.F. and C.F. are lowered the ", 1, 5, 14, 490, 15, 5, 880 ih FLbox "modulator amplitude should be also be lowered to maintain a ", 1, 5, 14, 490, 15, 5, 900 ih FLbox "constant spectral intensity. This is why in conventionally ", 1, 5, 14, 490, 15, 5, 920 ih FLbox "implemented FM synthesis a new parameter called 'the index of", 1, 5, 14, 490, 15, 5, 940 ih FLbox "modulation' is derived that is directly proportional to the ", 1, 5, 14, 490, 15, 5, 960 ih FLbox "peak deviation (amplitude) of the modulator and inversely ", 1, 5, 14, 490, 15, 5, 980 ih FLbox "proportional to carrier modulator frequency. ", 1, 5, 14, 490, 15, 5, 1000 ih FLbox "The next example makes use of the 'index of modulation' ", 1, 5, 14, 490, 15, 5, 1020 ih FLbox "formula. ", 1, 5, 14, 490, 15, 5, 1040 ih FLbox " ", 1, 5, 14, 490, 15, 5, 1060 ih FLbox " SIMPLIFIED SCHEMATIC FOR A MODULATOR AND CARRIER FM PAIR ", 1, 5, 14, 490, 15, 5, 1080 ih FLbox " ---------------------------------------------------------- ", 1, 5, 14, 490, 15, 5, 1100 ih FLbox " ", 1, 5, 14, 490, 15, 5, 1120 ih FLbox " +-----------+ ", 1, 5, 14, 490, 15, 5, 1140 ih FLbox " | oscil | ", 1, 5, 14, 490, 15, 5, 1160 ih FLbox " |(modulator)| ", 1, 5, 14, 490, 15, 5, 1180 ih FLbox " +-----+-----+ ", 1, 5, 14, 490, 15, 5, 1200 ih FLbox " | ", 1, 5, 14, 490, 15, 5, 1220 ih FLbox " | ", 1, 5, 14, 490, 15, 5, 1240 ih FLbox " | ", 1, 5, 14, 490, 15, 5, 1260 ih FLbox " | ", 1, 5, 14, 490, 15, 5, 1280 ih FLbox " | ", 1, 5, 14, 490, 15, 5, 1300 ih FLbox " +-----------+ ", 1, 5, 14, 490, 15, 5, 1320 ih FLbox " | oscil | ", 1, 5, 14, 490, 15, 5, 1340 ih FLbox " | (carrier) | ", 1, 5, 14, 490, 15, 5, 1360 ih FLbox " +-----+-----+ ", 1, 5, 14, 490, 15, 5, 1380 ih FLbox " | ", 1, 5, 14, 490, 15, 5, 1400 ih FLbox " | ", 1, 5, 14, 490, 15, 5, 1420 ih FLbox " OUT ", 1, 5, 14, 490, 15, 5, 1440 ih FLbox " ", 1, 5, 14, 490, 15, 5, 1460 FLscrollEnd FLpanel_end FLrun ;RUN THE FLTK WIDGET THREAD ;END OF FLTK INTERFACE CODE;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; instr 1 if gkOnOff!=-1 kgoto CONTINUE ;SENSE IF FLTK INSTRUMENT ON/OFF SWITCH IS NOT OFF (IN WHICH CASE SKIP THE NEXT LINE) turnoff ;TURN THIS INSTRUMENT OFF IMMEDIATELY CONTINUE: ;A LABEL ;OUTPUT OPCODE AMPLITUDE | FREQUENCY | FUNCTION_TABLE aModulator oscili gkModAmp, gkModFreq, 1 ;DEFINE THE MODULATOR WAVEFORM aCarrier oscili gkCarrAmp, gkCarrFreq+aModulator, 1 ;DEFINE THE CARRIER WAVEFORM (NOTE HOW ITS FREQUENCY IS MODULATED (THROUGH ADDITION) BY THE AUDIO OUTPUT OF THE MODULATOR WAVEFORM) outs aCarrier, aCarrier ;SEND THE AUDIO OUTPUT OF THE CARRIER WAVEFORM *ONLY* TO THE OUTPUTS endin f 1 0 129 10 1 ;A SINE WAVE (INTERPOLATING OSCILLATOR OPCODES ARE USED THEREFORE A SMALL TABLE SIZE (+1) CAN BE USED) f 0 3600i 1 0 3600 ;DUMMY SCORE EVENT - KEEPS REALTIME PERFORMANCE GOING FOR ONE HOUR