follow2EnvelopeFilter.csd Written by Iain McCurdy -idevaudio -odevaudio -b400 sr = 44100 ksmps = 100 nchnls = 2 0dbfs = 1 ;MAXIMUM AMPLITUDE REGARDLESS OF BIT DEPTH ;FLTK INTERFACE CODE;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; FLcolor 255, 255, 255, 0, 0, 0 ; LABEL | WIDTH | HEIGHT | X | Y FLpanel "follow2", 500, 450, 0, 0 ;SWITCHES ON | OFF | TYPE | WIDTH | HEIGHT | X | Y | OPCODE | INS | STARTTIM | IDUR gkOnOff,ihOnOff FLbutton "On/Off", 1, 0, 22, 140, 25, 5, 5, 0, 1, 0, -1 FLsetColor2 255, 255, 50, ihOnOff ;SET SECONDARY COLOUR TO YELLOW ; WIDTH | HEIGHT | X | Y idatt FLvalue "", 80, 20, 5, 75 idrel FLvalue "", 80, 20, 5, 125 idsensitivity FLvalue "", 80, 20, 5, 175 idoffset FLvalue "", 80, 20, 5, 225 idres FLvalue "", 80, 20, 5, 275 idspeed FLvalue "", 80, 20, 5, 325 idmix FLvalue "", 80, 20, 5, 375 idamp FLvalue "", 80, 20, 5, 425 ; MIN | MAX | EXP | TYPE | DISP | WIDTH | HEIGHT | X | Y gkatt, ihatt FLslider "Envelope Follow Attack", 0.001, 0.5, 0, 23, idatt, 490, 25, 5, 50 gkrel, ihrel FLslider "Envelope Follow Release", 0.001, 0.5, 0, 23, idrel, 490, 25, 5, 100 gksensitivity, ihsensitivity FLslider "Envelope Follow Sensitivity (Hz.)", 1, 20000, -1, 23, idsensitivity, 490, 25, 5, 150 gkoffset ihoffset FLslider "Filter Cutoff Offset (Hz.)", 20, 15000, -1, 23, idoffset, 490, 25, 5, 200 gkres, ihres FLslider "Filter Resonance", 0, 1, 0, 23, idres, 490, 25, 5, 250 gkspeed, ihspeed FLslider "File Playback Speed", 0.125, 2, 0, 23, idspeed, 490, 25, 5, 300 gkmix, ihmix FLslider "Filter Dry/Wet Mix", 0, 1, 0, 23, idmix, 490, 25, 5, 350 gkamp, ihamp FLslider "Output Gain", 0, 2, 0, 23, idamp, 490, 25, 5, 400 gkingain,ihingain FLslider "Live Input Gain", 0, 1, 0, 23, -1, 140, 20, 350, 5 ;GENERAL_TEXT_SETTINGS SIZE | FONT | ALIGN | RED | GREEN | BLUE FLlabel 13, 1, 1, 255, 255, 255 ;LABELS MADE INVISIBLE FLcolor2 255, 255, 50 ;SET SECONDARY COLOUR TO YELLOW ; FLBUTBANK TYPE | NUMX | NUMY | WIDTH | HEIGHT | X | Y | OPCODE gkinput, ihinput FLbutBank 12, 1, 2, 30, 40, 150, 0, -1 ;GENERAL_TEXT_SETTINGS SIZE | FONT | ALIGN | RED | GREEN | BLUE FLlabel 13, 5, 4, 0, 0, 0 ;LABELS MADE VISIBLE AGAIN ;TEXT BOXES TYPE | FONT | SIZE | WIDTH | HEIGHT | X | Y ih FLbox "Live Input", 1, 2, 12, 70, 20, 180, 0 ih FLbox "Sound File", 1, 2, 12, 70, 20, 180, 20 FLsetVal_i 0.001, ihatt FLsetVal_i 0.2, ihrel FLsetVal_i 10000, ihsensitivity FLsetVal_i 100, ihoffset FLsetVal_i 0.5, ihres FLsetVal_i 0.5, ihspeed FLsetVal_i 1, ihmix FLsetVal_i 1, ihamp FLsetVal_i 1, ihinput FLpanel_end ;END OF PANEL CONTENTS ;INSTRUCTIONS AND INFO PANEL FLpanel " ", 515, 560, 512, 0 ;TEXT BOXES TYPE | FONT | SIZE | WIDTH | HEIGHT | X | Y ih FLbox " follow2 ", 1, 5, 14, 490, 20, 5, 0 ih FLbox "-------------------------------------------------------------", 1, 5, 14, 490, 20, 5, 20 ih FLbox "The follow2 opcode outputs an amplitude following signal ", 1, 5, 14, 490, 20, 5, 40 ih FLbox "based on an input audio signal. The output signal will be ", 1, 5, 14, 490, 20, 5, 60 ih FLbox "unipolar (i.e. only positive values) and the response of the ", 1, 5, 14, 490, 20, 5, 80 ih FLbox "envelope follower to dynamic transients can be tailored using", 1, 5, 14, 490, 20, 5, 100 ih FLbox "follow2's input arguments for attack time and release time. ", 1, 5, 14, 490, 20, 5, 120 ih FLbox "This example demonstrates a very common use of this control ", 1, 5, 14, 490, 20, 5, 140 ih FLbox "signal in that it is used to derive the cutoff frequency of a", 1, 5, 14, 490, 20, 5, 160 ih FLbox "lowpass filter. Therefore as the amplitude of the input ", 1, 5, 14, 490, 20, 5, 180 ih FLbox "signal increases the cutoff frequency of the filter also ", 1, 5, 14, 490, 20, 5, 200 ih FLbox "rises. Some additional controls are offered to allow the user", 1, 5, 14, 490, 20, 5, 220 ih FLbox "to further refine the envelope follower response and some ", 1, 5, 14, 490, 20, 5, 240 ih FLbox "other aspects of the effect. ", 1, 5, 14, 490, 20, 5, 260 ih FLbox "'Envelope Follow Sensitivity' defines the increase in hertz ", 1, 5, 14, 490, 20, 5, 280 ih FLbox "that a sound of maximum intensity will apply to the filter ", 1, 5, 14, 490, 20, 5, 300 ih FLbox "cutoff value. ", 1, 5, 14, 490, 20, 5, 320 ih FLbox "'Filter Cutoff Offset' sets the base value for the filter ", 1, 5, 14, 490, 20, 5, 340 ih FLbox "cutoff in hertz before envelope following influence has been ", 1, 5, 14, 490, 20, 5, 360 ih FLbox "added. ", 1, 5, 14, 490, 20, 5, 380 ih FLbox "The 'moogvcf2' resonant lowpass filter has been used because ", 1, 5, 14, 490, 20, 5, 400 ih FLbox "it allows us to use an a-rate variable for cutoff frequency. ", 1, 5, 14, 490, 20, 5, 420 ih FLbox "The output from follow2 is also a-rate. If we wanted to use ", 1, 5, 14, 490, 20, 5, 440 ih FLbox "a different opcode that only permitted the use of k-rate ", 1, 5, 14, 490, 20, 5, 460 ih FLbox "variables to define cutoff frequency then we could have used ", 1, 5, 14, 490, 20, 5, 480 ih FLbox "the 'downsamp' opcode to convert from a-rate to k-rate. ", 1, 5, 14, 490, 20, 5, 500 ih FLbox "The user can choose between using a stored file or the live ", 1, 5, 14, 490, 20, 5, 520 ih FLbox "input as the source signal for the envelope follower. ", 1, 5, 14, 490, 20, 5, 540 FLpanel_end FLrun ;RUN THE FLTK WIDGET THREAD ;END OF FLTK INTERFACE CODE;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; instr 1 if gkOnOff=0 then turnoff ;TURN THIS INSTRUMENT OFF IMMEDIATELY endif if gkinput=0 then ;IF INPUT SWITCH IS SET TO 'LIVE INPUT' THEN... aL, aR ins ;READ THE LIVE AUDIO INPUT TO THE COMPUTER aL = aL * gkingain ;SCALE LIVE INPUT WITH FLTK SLIDER aR = aR * gkingain ;SCALE LIVE INPUT WITH FLTK SLIDER elseif gkinput=1 then ;OR ELSE IF INPUT SWITCH IS SET TO 'SOUND FILE' THEN... ;OUTPUT OPCODE FILE_PATH | SPEED | INSKIP | LOOPING_0=OFF/1=ON aL diskin2 "loop.wav", gkspeed, 0, 1 ;CREATE AN AUDIO SIGNAL aR = aL ;ASSIGN RIGHT CHANNEL TO BE THE SAME AS THE LEFT CHANNEL SIGNAL endif ;END OF CONDITIONAL BRANCHING kporttime linseg 0,0.001,0.02 ;FUNCTION THAT RAMPS UP QUICKLY FROM ZERO AND LEVELS OFF AT 0.02 koffset portk gkoffset, kporttime ;APPLY PORTAMENTO SMOOTHING TO FLTK SLIDER VARIABLE koffset ;LEFT CHANNEL=========================================================================================================================================================== afollowL follow2 aL, gkatt, gkrel ;CREATE AN ENVELOPE FOLLOWING SIGNAL FROM THE AUDIO SIGNAL acfL limit (afollowL*gksensitivity)+koffset,20,sr/2 ;LIMIT FILTER CUTOFF FREQUENCY VARIABLE TO PREVENT VALUES BEYOND THE NYQUIST FREQUENCY BEING ATTEMPTED afiltL moogvcf2 aL, acfL, gkres ;FILTER THE AUDIO SIGNAL USING THE moogvcf2 RESONANT LOWPASS FILTER amixL ntrpol aL, afiltL, gkmix ;CREATE A DRY/WET MIX BETWEEN THE ORIGINAL SIGNAL AND THE FILTERED SIGNAL ;======================================================================================================================================================================= ;RIGHT CHANNEL========================================================================================================================================================== afollowR follow2 aR, gkatt, gkrel ;CREATE AN ENVELOPE FOLLOWING SIGNAL FROM THE AUDIO SIGNAL acfR limit (afollowR*gksensitivity)+koffset,20,sr/2 ;LIMIT FILTER CUTOFF FREQUENCY VARIABLE TO PREVENT VALUES BEYOND THE NYQUIST FREQUENCY BEING ATTEMPTED afiltR moogvcf2 aR, acfR, gkres ;FILTER THE AUDIO SIGNAL USING THE moogvcf2 RESONANT LOWPASS FILTER amixR ntrpol aR, afiltR, gkmix ;CREATE A DRY/WET MIX BETWEEN THE ORIGINAL SIGNAL AND THE FILTERED SIGNAL ;======================================================================================================================================================================= outs amixL * gkamp, amixR * gkamp ;SEND DRY/WET MIX TO THE SPEAKERS - RESCALE WITH GAIN CONTROL endin f 0 3600 ;DUMMY SCORE EVENT - PERMITS REALTIME PERFORMANCE FOR 1 HOUR