; mediank.csd ; Written by Iain McCurdy, 2014. -odac -dm0 sr = 48000 ;SAMPLE RATE ksmps = 6000 ;NUMBER OF AUDIO SAMPLES IN EACH CONTROL CYCLE nchnls = 1 ;NUMBER OF CHANNELS (2=STEREO) 0dbfs = 1 ;FLTK INTERFACE CODE;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; FLcolor 255, 255, 255, 0, 0, 0 ; LABEL | WIDTH | HEIGHT | X | Y FLpanel "mediank", 500, 240, 0, 0 ;BORDERS TYPE | FONT | SIZE | WIDTH | HEIGHT | X | Y ih FLbox " ", 3, 9, 15, 490, 90, 5, 10 ; FLsetColor 20,205,205,ih ;TEXT BOXES TYPE | FONT | SIZE | WIDTH | HEIGHT | X | Y ih FLbox "User Input", 1, 10, 14, 100, 15, 200, 16 FLsetColor 20,205,205,ih ;COUNTERS MIN | MAX | STEP1 | STEP2 | TYPE | WIDTH | HEIGHT | X | Y | OPCODE gkSampSize, ihSampSize FLcount "Sample Window", 1, 41, 1, 1, 2, 115, 25, 10, 40, -1 ;VALUE DISPLAY BOXES LABEL | WIDTH | HEIGHT | X | Y iddeviation FLvalue "", 60, 17, 130, 65 ;SLIDERS MIN | MAX | EXP | TYPE | DISP | WIDTH | HEIGHT | X | Y gkdeviation,ihdeviation FLslider "Noise Level", 0, 1, 0, 23, iddeviation, 360, 25, 130, 40 ;BORDERS TYPE | FONT | SIZE | WIDTH | HEIGHT | X | Y ih FLbox " ", 3, 9, 15, 490, 125, 5, 105 ; FLsetColor 200,255,150,ih ;TEXT BOXES TYPE | FONT | SIZE | WIDTH | HEIGHT | X | Y ih FLbox "Data Monitor", 1, 10, 14, 100, 15, 200, 111 FLsetColor 200,255,150,ih ;VALUE DISPLAY BOXES LABEL | WIDTH | HEIGHT | X | Y idinput FLvalue "", 60, 17, 10, 160 idoutput FLvalue "", 60, 17, 10, 210 ;SLIDERS MIN | MAX | EXP | TYPE | DISP | WIDTH | HEIGHT | X | Y gkinput,gihinput FLslider "Noisy Input", -1, 1, 0, 23, idinput, 480, 25, 10, 135 gkoutput,gihoutput FLslider "Filtered Output", -1, 1, 0, 23, idoutput, 480, 25, 10, 185 ;SET INITIAL VALUES OF FLTK VALUATORS ; VALUE | HANDLE FLsetVal_i 0, gihinput FLsetVal_i 0, gihoutput FLsetVal_i 9, ihSampSize FLsetVal_i 0.3, ihdeviation FLpanel_end ;INSTRUCTIONS AND INFO PANEL FLpanel " ", 500, 780, 512, 0 ;TEXT BOXES TYPE | FONT | SIZE | WIDTH | HEIGHT | X | Y ih FLbox " mediank ", 1, 6, 14, 490, 20, 5, 0 ih FLbox "-------------------------------------------------------------", 1, 6, 14, 490, 20, 5, 20 ih FLbox "'median' and 'mediank' apply median filtering to an input ", 1, 5, 14, 490, 20, 5, 40 ih FLbox "signal. (a-rate signal with 'median' and k-rate signals with ", 1, 5, 14, 490, 20, 5, 60 ih FLbox "'mediank'.) ", 1, 5, 14, 490, 20, 5, 80 ih FLbox "Median filtering takes a range of sequential values - ", 1, 5, 14, 490, 20, 5, 100 ih FLbox "referred to as a window - arranges them in order of size and ", 1, 5, 14, 490, 20, 5, 120 ih FLbox "outputs the middle value. This can be a useful method of ", 1, 5, 14, 490, 20, 5, 140 ih FLbox "filtering noise from a signal and smoothing data changes by ", 1, 5, 14, 490, 20, 5, 160 ih FLbox "dumping irrational values - values that would skew the output", 1, 5, 14, 490, 20, 5, 180 ih FLbox "of normal averaging (or lowpass filtering / portamento ", 1, 5, 14, 490, 20, 5, 200 ih FLbox "filtering). ", 1, 5, 14, 490, 20, 5, 220 ih FLbox "Median filtering is used a lot in digital image processing to", 1, 5, 14, 490, 20, 5, 240 ih FLbox "remove noise created by electrical interference. It is also ", 1, 5, 14, 490, 20, 5, 260 ih FLbox "useful for smoothing data received by electronic sensors and ", 1, 5, 14, 490, 20, 5, 280 ih FLbox "for 'debouncing'. ", 1, 5, 14, 490, 20, 5, 300 ih FLbox "In this example a noisy signal of zeros is created (i.e. ", 1, 5, 14, 490, 20, 5, 320 ih FLbox "occasional '1's and '-1's will occur) at a rate of 8 values ", 1, 5, 14, 490, 20, 5, 340 ih FLbox "per second. The likelihood of wrong values is governed by the", 1, 5, 14, 490, 20, 5, 360 ih FLbox "'noise' level slider. Rate of generation of these values is ", 1, 5, 14, 490, 20, 5, 380 ih FLbox "governed by the control rate and can be changed by the user ", 1, 5, 14, 490, 20, 5, 400 ih FLbox "by changing the value of ksmps. ", 1, 5, 14, 490, 20, 5, 420 ih FLbox "'Sample Window' defines the number of values in each ", 1, 5, 14, 490, 20, 5, 440 ih FLbox "filtering interrogation. Noisier signals will demand a larger", 1, 5, 14, 490, 20, 5, 460 ih FLbox "sample window but excessively large sample windows will ", 1, 5, 14, 490, 20, 5, 480 ih FLbox "demand more from the CPU and slow response of the output ", 1, 5, 14, 490, 20, 5, 500 ih FLbox "signal in response to changes in the input signal. ", 1, 5, 14, 490, 20, 5, 520 ih FLbox "If sample window is size '1' then the median filter simply ", 1, 5, 14, 490, 20, 5, 540 ih FLbox "outputs the input. If window size is an even number then ", 1, 5, 14, 490, 20, 5, 560 ih FLbox "is no central value, in this situation the output value is ", 1, 5, 14, 490, 20, 5, 580 ih FLbox "the mean between the two central values. For this reason it ", 1, 5, 14, 490, 20, 5, 600 ih FLbox "is normal to use an odd number for the window size. ", 1, 5, 14, 490, 20, 5, 620 ih FLbox "In practice, when deciding upon what value to use for sample ", 1, 5, 14, 490, 20, 5, 640 ih FLbox "window size it is best to devise some method of monitoring ", 1, 5, 14, 490, 20, 5, 660 ih FLbox "the input and the output and to monitor what the minimum size", 1, 5, 14, 490, 20, 5, 680 ih FLbox "required is to remove the noise. It is also an option to ", 1, 5, 14, 490, 20, 5, 700 ih FLbox "chain median filters in series, the second one using a much ", 1, 5, 14, 490, 20, 5, 720 ih FLbox "smaller sample window size (e.g. '3') to filter out rogue ", 1, 5, 14, 490, 20, 5, 740 ih FLbox "values. ", 1, 5, 14, 490, 20, 5, 760 FLpanel_end FLrun ;RUN THE FLTK WIDGET THREAD ;END OF FLTK INTERFACE CODE;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; alwayson 1 ; Instrument 1 always on instr 1 kval random -1-gkdeviation, 1+gkdeviation ; Random value. New one each k-cycle. kval = int(kval) ; Turn it into an integer. Remove fractional part. ktrig changed kval ; If it has changed from last last k-cycle value, generate a trigger. FLsetVal ktrig,kval,gihinput ; Send changes in the random value to the 'Input' slider. kfilt mediank kval, gkSampSize, 41 ; Median filter the stream of random values. ktrig changed kfilt ; If median filtered values has changed generate a trigger. FLsetVal ktrig,kfilt,gihoutput ; Send changes in the filtered values to the 'Output' slider. endin