real time spectrogram

realtimeaudio.py → realtime_spectrogram.py

 """
-PyAudio Example: Make a wire between input and output (i.e., record a
-few samples and play them back immediately).
+musicinformationretrieval.com/realtime_spectrogram.py
 
-This is the callback (non-blocking) version.
+PyAudio example: display a live spectrogram in the terminal.
+
+For more examples using PyAudio:
+    https://github.com/mwickert/scikit-dsp-comm/blob/master/sk_dsp_comm/pyaudio_helper.py
 """
+import librosa
 import numpy
 import pyaudio
 import time
 
-WIDTH = 2
 CHANNELS = 1
 RATE = 44100
+FRAMES_PER_BUFFER = 1000
+N_FFT = 4096
+SCREEN_WIDTH = 178
+
+BIN_LO = N_FFT*librosa.note_to_hz('C2')/RATE
+BIN_HI = N_FFT*librosa.note_to_hz('C7')/RATE
+FREQ_BINS = numpy.geomspace(BIN_LO, BIN_HI, SCREEN_WIDTH).astype('int')
 
 p = pyaudio.PyAudio()
 
-def g(z):
-    if z:
-        return '*'
-    else:
-        return ' '
+def generate_string_from_audio(audio_data):
+    x_fft = numpy.fft.rfft(audio_data, n=N_FFT)
+    X = numpy.log10(1 + 0.1*abs(x_fft))
+
+    char_list = [' ']*SCREEN_WIDTH
+
+    for i in range(len(FREQ_BINS)):
+        b = FREQ_BINS[i]
+        if X[b] > 0.3:
+            char_list[i] = '*'
+        elif i % 30 == 29:
+            char_list[i] = '|'
+    return ''.join(char_list)
 
 def callback(in_data, frame_count, time_info, status):
     audio_data = numpy.fromstring(in_data, dtype=numpy.float32)
-    X = numpy.log(abs(numpy.fft.fft(audio_data)))
-    print( ''.join(g(z > 1.5) for z in X[:140]) )
+    print( generate_string_from_audio(audio_data) )
     return (in_data, pyaudio.paContinue)
 
 stream = p.open(format=pyaudio.paFloat32,
@@ -31,12 +47,13 @@ stream = p.open(format=pyaudio.paFloat32,
                 rate=RATE,
                 input=True,
                 output=True,
+                frames_per_buffer=FRAMES_PER_BUFFER,
                 stream_callback=callback)
 
 stream.start_stream()
 
 while stream.is_active():
-    time.sleep(0.2)
+    time.sleep(0.100)
 
 stream.stop_stream()
 stream.close()