SOUND METER (Annotated)

CPX_soundMETER__annotated.py

#importz
#-----------------------------------------------------------------
import array
import math
import audiobusio
import board
from adafruit_circuitplayground.express import cpx
#-----------------------------------------------------------------

#functions
#mathy stuff
#-----------------------------------------------------------------
def constrain(value, floor, ceiling):
    return max(floor, min(value, ceiling))


def log_scale(input_value, input_min, input_max, output_min, output_max):
    normalized_input_value = (input_value - input_min) / (input_max - input_min)
    return output_min + math.pow(normalized_input_value, 0.630957) * (output_max - output_min)


def normalized_rms(values):
    minbuf = int(sum(values) / len(values))
    return math.sqrt(sum(float(sample - minbuf) *
                         (sample - minbuf) for sample in values) / len(values))
#-----------------------------------------------------------------

#-----------------------------------------------------------------
# For CircuitPython 2.x:
mic = audiobusio.PDMIn(board.MICROPHONE_CLOCK, board.MICROPHONE_DATA,
                       frequency=16000, bit_depth=16)
# For CircuitPython 3.0 and up, "frequency" is now called "sample_rate".
# Comment out the mic and frequency lines above and uncomment those lines below.
# mic = audiobusio.PDMIn(board.MICROPHONE_CLOCK, board.MICROPHONE_DATA,
#                        sample_rate=16000, bit_depth=16)


samples = array.array('H', [0] * 160)
mic.record(samples, len(samples))
input_floor = normalized_rms(samples) + 10

# Lower number means more sensitive - more LEDs will light up with less sound.
sensitivity = 500
input_ceiling = input_floor + sensitivity

peak = 0
#-----------------------------------------------------------------

#MAIN LOOP
#-----------------------------------------------------------------
while True:

    #THIS CODE "RECORDS" or takes in sound
    #----------------------------------------
    #record something
    mic.record(samples, len(samples))
    #normalize the values
    magnitude = normalized_rms(samples)
    #show us what is happening
    #(this syntax means we can use the plotter in mu)
    print((magnitude,))
    #----------------------------------------

    #convert audio to linear values
    """
    audio volume is in a unit called a decibel
    decibels scale logarithmically rather than linearly
    This is to make more intrinsic sense to 
    how humans perceive audio
    (when we perceive something as "twice as loud" as it was before
    the actual volume of that sound was more than twice as loud as it 
    was before. Logarithmic values are helpful for aligning with
    our perception of reality, however this means we must 
    CONVERT the values to scale linearly. This code does that)
    """
    c = log_scale(constrain(magnitude, input_floor, input_ceiling),
                  input_floor, input_ceiling, 0, 10)

    #clear everything out each loop through
    cpx.pixels.fill((0, 0, 0))

    #go through all pixels
    for i in range(10):
        #if the current pixel is not the value we are trying to
        #represent, show the color
        if i < c:
            #make the pixel "redness" proportional
            #to the curent value of i
            cpx.pixels[i] = (i * (255 // 10), 50, 0)

        #now we're finding the peak or highest value
        #peak starts at 0 (see above)
        # this looks like it is needed to figure out, 
        # how many pixels to light up
        if c >= peak:
            peak = min(c, 10 - 1)
        elif peak > 0:
            peak = peak - 1
        if peak > 0:
            cpx.pixels[int(peak)] = (80, 0, 255)

    #I was trying to ascertain if this is a deprecated 
    #(old) function, not sure exactly happens here.
    cpx.pixels.show()