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Realtime oscilloscope in 20 lines of Python, via soundcard & OpenCV
import numpy as np
import cv2
import soundcard as sc # Get it from https://github.com/bastibe/SoundCard
imWidth, imHeight = 1024, 512 # screen size
def draw_wave(screen, mono_audio, xs, title="oscilloscope", gain=5):
screen *= 0 # clear the screen
ys = imHeight/2*(1 - np.clip( gain * mono_audio[0:len(xs)], -1, 1)) # the y-values of the waveform
pts = np.array(list(zip(xs,ys))).astype(np.int) # pair up xs & ys
cv2.polylines(screen,[pts],False,(0,255,0)) # connect points w/ lines
cv2.imshow(title, screen) # show what we've got
default_mic = sc.default_microphone()
screen = np.zeros((imHeight,imWidth,3), dtype=np.uint8) # 3=color channels
xs = np.arange(imWidth).astype(np.int) # x values of pixels
while (1): # keep looping until someone stops this
with default_mic.recorder(samplerate=44100) as mic:
audio_data = mic.record(numframes=1024) # get some audio from the mic
draw_wave(screen, audio_data[:,0], xs) # draw left channel
key = cv2.waitKey(1) & 0xFF # keyboard input
if ord('q') == key: # quit key
break
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@drscotthawley drscotthawley commented May 17, 2018

The minus sign in the "1 - np.clip..." on line 7 is because in computer graphics, "up" is negative.

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@drscotthawley drscotthawley commented Jan 14, 2021

Note: Works on Mac, but soundcard lib yields a failed assertion on Linux / pulse audio: bastibe/SoundCard#29

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