doppler.csd Written by Iain McCurdy, 2010 -odac -dm0 sr = 44100 ;SAMPLE RATE ksmps = 32 ;NUMBER OF AUDIO SAMPLES IN EACH CONTROL CYCLE nchnls = 2 ;NUMBER OF CHANNELS (2=STEREO) 0dbfs = 1 ;MAXIMUM AMPLITUDE REGARDLESS OF BIT DEPTH ;FLTK INTERFACE CODE;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; FLcolor 255, 255, 255, 0, 0, 0 ;SET INTERFACE COLOURS ; LABEL | WIDTH | HEIGHT | X | Y FLpanel "doppler", 500, 500, 0, 0 ;SWITCHES ON | OFF | TYPE | WIDTH | HEIGHT | X | Y | OPCODE | INS | STARTTIM | IDUR gkOnOff,ihOnOff FLbutton "On/Off", 1, 0, 22, 150, 25, 5, 5, 0, 1, 0, -1 FLsetColor2 255, 255, 50, ihOnOff ;SET SECONDARY COLOUR TO YELLOW ;NUMBER DISPLAY BOXES WIDTH | HEIGHT | X | Y idRoomSize FLvalue "", 80, 20, 5, 175 idfiltercutoff FLvalue "", 80, 20, 5, 225 idspeed FLvalue "", 80, 20, 5, 325 ;SLIDERS MIN | MAX | EXP | TYPE | DISP | WIDTH | HEIGHT | X | Y gksource, gihsource FLslider "Source Position", 0, 1, 0, 3, -1, 490, 25, 5, 50 gkmicrophone, ihmicrophone FLslider "Microphone", 0, 1, 0, 3, -1, 490, 25, 5, 100 gkRoomSize, ihRoomSize FLslider "Room Size (metres)", 0.1, 100, -1, 23, idRoomSize, 490, 25, 5, 150 gkfiltercutoff, ihfiltercutoff FLslider "Filter Cutoff", 1, 20, 0, 23, idfiltercutoff, 490, 25, 5, 200 gkVCOoct, ihVCOoct FLslider "VCO Pitch", 6, 10, 0, 23, -1, 240, 25, 5, 250 gksiren, ihsiren FLslider "Siren Depth", 0, 1, 0, 23, -1, 240, 25, 255, 250 gkspeed, ihspeed FLslider "LFO Speed", 0.001, 10, -1, 23, idspeed, 490, 25, 5, 300 gkdepth, ihdepth FLslider "LFO Depth", 0, 0.5, 0, 23, -1, 490, 25, 5, 350 gkampscale, ihampscale FLslider "Distance:Amplitude Scaling", 0, 1, 0, 23, -1, 490, 25, 5, 400 gkOutAmp, ihOutAmp FLslider "Output Amplitude", 0, 1, 0, 23, -1, 490, 25, 5, 450 ;INITIALISATION OF SLIDERS VALUE | HANDLE FLsetVal_i 0.3, gihsource FLsetVal_i 0.5, ihmicrophone FLsetVal_i 40, ihRoomSize FLsetVal_i 6, ihfiltercutoff FLsetVal_i 9, ihVCOoct FLsetVal_i 1, ihsiren FLsetVal_i 0.08, ihspeed FLsetVal_i 0.5, ihdepth FLsetVal_i 0.98, ihampscale FLsetVal_i 0.5, ihOutAmp FLpanel_end ;END OF PANEL CONTENTS ;INSTRUCTIONS AND INFO PANEL FLpanel " ", 515, 480, 512, 0 ;TEXT BOXES TYPE | FONT | SIZE | WIDTH | HEIGHT | X | Y ih FLbox " doppler ", 1, 5, 14, 490, 20, 5, 0 ih FLbox "-------------------------------------------------------------", 1, 5, 14, 490, 20, 5, 20 ih FLbox "The opcode 'doppler' approximates the pitch shifting effect ", 1, 5, 14, 490, 20, 5, 40 ih FLbox "that occurs when a sound source moves with respect to a point", 1, 5, 14, 490, 20, 5, 60 ih FLbox "of reception such as a listener or a microphone. Moving the ", 1, 5, 14, 490, 20, 5, 80 ih FLbox "microphone with respect to a static sound source will also ", 1, 5, 14, 490, 20, 5, 100 ih FLbox "induce the doppler effect. The doppler opcode will allow the ", 1, 5, 14, 490, 20, 5, 120 ih FLbox "sound source and microphone locations to be moved at control ", 1, 5, 14, 490, 20, 5, 140 ih FLbox "rate. An internal filter smooths stepping that might occur, ", 1, 5, 14, 490, 20, 5, 160 ih FLbox "particularly when k-rate is low. ", 1, 5, 14, 490, 20, 5, 180 ih FLbox "In this implementation the locations of the sound source and ", 1, 5, 14, 490, 20, 5, 200 ih FLbox "the microphone can be moved manually or the movement of the ", 1, 5, 14, 490, 20, 5, 220 ih FLbox "sound source can be modulated by an LFO. The scale of the ", 1, 5, 14, 490, 20, 5, 240 ih FLbox "sliders for 'Source Position' and 'Microphone Position' is ", 1, 5, 14, 490, 20, 5, 260 ih FLbox "set using the 'Room Size' slider. ", 1, 5, 14, 490, 20, 5, 280 ih FLbox "In keeping with the classic scenario used to illustrate the ", 1, 5, 14, 490, 20, 5, 300 ih FLbox "doppler effect, the source sound in this demonstration is an ", 1, 5, 14, 490, 20, 5, 320 ih FLbox "imitation of a siren that might be heard on a fire engine. ", 1, 5, 14, 490, 20, 5, 340 ih FLbox "To facilitate manual modulation of the 'Source Position' ", 1, 5, 14, 490, 20, 5, 360 ih FLbox "slider, reduce 'LFO Depth' to zero. ", 1, 5, 14, 490, 20, 5, 380 ih FLbox "Separate additions in this demonstration is panning that ", 1, 5, 14, 490, 20, 5, 400 ih FLbox "reflects the source position with respect to the microphone ", 1, 5, 14, 490, 20, 5, 420 ih FLbox "position and amplitude scaling that induces amplitude ", 1, 5, 14, 490, 20, 5, 440 ih FLbox "reduction as the source sound becomes more distant. ", 1, 5, 14, 490, 20, 5, 460 FLpanel_end FLrun ;RUN THE FLTK WIDGET THREAD ;END OF FLTK INTERFACE CODE;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;AMPLITUDE SCALING CURVE giampcurve ftgen 0,0,131072,5,0.01,131072*0.5,1,131072*0.5,0.01 instr 1 if gkOnOff=0 then ;IF ON/OFF SWITCH IS OFF... turnoff ;TURN THIS INSTRUMENT OFF IMMEDIATELY endif ;END OF THIS CONDITIONAL BRANCH ;LFO(modulates source position slider)================= klfo lfo gkdepth, gkspeed, 1 ;SINE WAVE klfo = klfo + 0.5 ;OFFSET INTO THE POSITIVE DOMAIN ;ktrig changed klfo ;UPDATING THE SLIDER EVERY K CYCLE MIGHT BE TOO FREQUENT AND MAY CAUSE PERFORMANCE ISSUE IN WHICH CASE USE A SEPARATE TRIGGER AS SHOWN BELOW ktrig metro 50 ;SLIDER UPDATE RATE FLsetVal ktrig, klfo, gihsource ;UPDATE 'Source Position' SLIDER ;====================================================== kporttime linseg 0, 0.001, 0.1 ;RAMPING UP PORTAMENTO TIME VARIABLE ;GENERATE A SOURCE SOUND (siren imitation)============= ksiren lfo 1, 1.3, 2 ;UNIPOLAR SQUARE WAVE LFO ktrig changed ksiren ;GENERATE A TRIGGER EACH TIME LFO VALUE CHANGES if ktrig=1 then ;IF LFO VALUE HAS JUST CHANGED... reinit SWAP_COLOUR ;BEGIN A REINITIALISATION PASS FROM LABEL 'SWAP_COLOUR' endif ;END OF THIS CONDITIONAL BRANCH SWAP_COLOUR: ;LABEL 'SWAP_COLOUR' if i(ksiren)=1 then ;IF SIREN IS 'HIGH'... FLsetColor2 0,0,255,gihsource ;SET SLIDER COLOUR TO BLUE else ;OTHERWISE... FLsetColor2 255,255,255,gihsource ;SET SLIDER COLOUR TO WHITE endif ;END OF THIS CONDITIONAL BRANCH rireturn ;RETURN FROM REINITIALISATION PASS asig vco2 1, cpsoct(gkVCOoct+ksiren*(gksiren/12)) ;GENERATE SIREN AUDIO asig tone asig, 1200 ;LOW PASS FILTER TO SOFTEN THE TONE ;======================================================= ;DOPPLER================================================ ispeedofsound init 340.29 ;SPEED OF SOUND DEFINED ksource portk gksource, kporttime ;SMOOTH SOURCE POSITION MOVEMENT kmicrophone portk gkmicrophone, kporttime ;SMOOTH MICROPHOPNE POSITION MOVEMENT ktrig changed gkfiltercutoff ;IF I-RATE VARIABLE SLIDER IS CHANGED GENERATE A '1' if ktrig=1 then ;IF TRIGGER IS '1'... reinit UPDATE ;BEGIN A REINITIALISATION PASS FROM LABEL 'UPDATE' endif ;END OF THIS CONDITIONAL BRANCH UPDATE: ;LABEL CALLED 'UPDATE' kdisp limit ksource-(kmicrophone-0.5), 0, 1 ;CALCULATE DISPLACEMENT (DISTANCE) BETWEEN SOURCE AND MICROPHONE AND LIMIT VALUE TO LIE BETWEEN ZERO AND 1 kamp table kdisp, giampcurve,1 ;READ AMPLITUDE SCALING VALUE FROM TABLE kamp ntrpol 1, kamp, gkampscale ;CALCULATE AMOUNT OF AMPLITUDE SCALING DESIRED BY THE USER FROM THE ON SCREEN SLIDER aout doppler asig*kamp, ksource*gkRoomSize, kmicrophone*gkRoomSize, ispeedofsound, i(gkfiltercutoff) ;APPLY DOPPLER EFFECT rireturn ;RETURN FROM REINITIALISATION PASS kpan = (gksource f 0 3600 ;DUMMY SCORE EVENT - PERMITS REAL-TIME PERFORMANCE FOR 1 HOUR