vu_meter.py WIP for special request

Upload vu_meter.py code for: kmein/vu-meter#1 (comment)

vu_meter.py

@@ -0,0 +1,176 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+#==============================================================================
+#
+#       vu_meter.py - Listen to microphone left/right and generate vu level
+#
+#==============================================================================
+"""
+
+FROM: https://github.com/kmein/vu-meter
+
+.gitignore          NOT INSTALLED
+LICENSE             NOT INSTALLED
+README.md           NOT INSTALLED
+amplitude.py                        THIS MODULE
+record.py           NOT INSTALLED
+vu_constants.py                     THIS MODULE
+vu_meter.py                         THIS MODULE
+
+ENHANCEMENTS:
+
+    1) Support Python environment variable for automatic python 2 / 3 selection
+    2) Add UTF-8 to support Python 2 (not necessary in this program though)
+    3) Reset maximal between songs (gap when 10 samples of zero strength)
+    4) Remove console output and write values to ramdisk (/run/user/1000)
+    5) Optional 'stereo' parameter to measure left & right channels
+    6) Utilize numpy which is usually auto-installed on distros
+    7) Include separate amplitude.py & vu_constants.py in main
+    8) Remove unused functions from Amplitude class
+
+"""
+
+from __future__ import print_function       # Must be first import
+from __future__ import with_statement       # Error handling for file opens
+
+import pyaudio
+import numpy as np              # January 24, 2021 support separate 2 channels
+import sys
+import math
+import struct
+#from amplitude import Amplitude
+
+RATE = 44100
+INPUT_BLOCK_TIME = 0.05
+INPUT_FRAMES_PER_BLOCK = int(RATE*INPUT_BLOCK_TIME)
+SHORT_NORMALIZE = 1.0 / 32768.0
+# Mono output
+VU_METER_FNAME  = "/run/user/1000/mserve.vu-meter-mono.txt"
+# Stereo output (Left and Right)
+VU_METER_LEFT_FNAME  = "/run/user/1000/mserve.vu-meter-left.txt"
+VU_METER_RIGHT_FNAME  = "/run/user/1000/mserve.vu-meter-right.txt"
+
+
+class Amplitude(object):
+    """ an abstraction for Amplitudes (with an underlying float value)
+    that packages a display function and many more
+    
+    January 25, 2021 - Remove unused add, sub, gt, eq, int & str functions
+    """
+
+    def __init__(self, value=0):
+        self.value = value
+
+    def __lt__(self, other):
+        return self.value < other.value
+
+    def to_int(self, scale=1):
+        """ convert an amplitude to an integer given a scale such that one can
+        choose the precision of the resulting integer """
+        return int(self.value * scale)
+
+    @staticmethod
+    def from_data(block):
+        """ generate an Amplitude object based on a block of audio input data """
+        count = len(block) / 2
+        shorts = struct.unpack("%dh" % count, block)
+        sum_squares = sum(s**2 * SHORT_NORMALIZE**2 for s in shorts)
+        return Amplitude(math.sqrt(sum_squares / count))
+
+    def display(self, mark, scale=50, fn=VU_METER_FNAME):
+        """ display an amplitude and another (marked) maximal Amplitude
+        graphically """
+        int_val = self.to_int(scale)
+        mark_val = mark.to_int(scale)
+        # delta = abs(int_val - mark_val)
+        # print(int_val * '*', (delta-1) * ' ', '|',mark_val,int_val,delta)
+        # January 23, 2021: Write values to ramdisk instead of displaying
+        with open(fn, "w") as vu_file:
+            vu_file.write(str(mark_val) + " " + str(int_val))
+
+
+def parse_data(data, channel_ndx, channel_cnt, maximal):
+    """
+        Process data from one channel
+    """
+    data = np.fromstring(data, dtype=np.int16)[channel_ndx::channel_cnt]
+    data = data.tostring()
+    amp = Amplitude.from_data(data)
+    gap = amp.value      # For signal test below.
+    if amp > maximal:
+        maximal = amp
+    return amp, maximal, gap
+
+
+def main():
+
+    # January 24, 2021 separate left and right channels
+    parameter = 'mono'
+    if (len(sys.argv)) == 2:
+        parameter = sys.argv[1]     # Null = 'mono', 'stereo' = Left & Right
+
+    audio = pyaudio.PyAudio()
+    reset_baseline_count = 0
+    stream = None
+    try:
+        stream = audio.open(format=pyaudio.paInt16,
+                            channels=2,
+                            rate=RATE,
+                            input=True,
+                            frames_per_buffer=INPUT_FRAMES_PER_BLOCK)
+
+        maximal = Amplitude()
+        maximal_l = maximal_r = maximal
+
+        while True:
+            data = stream.read(INPUT_FRAMES_PER_BLOCK)
+
+            # January 24, 2021 separate left and right channels
+            if parameter == 'stereo':
+                amp = None
+                amp_l, maximal_l, gap = parse_data(data, 0, 2, maximal_l)
+                amp_r, maximal_r, gap = parse_data(data, 1, 2, maximal_r)
+                if maximal_r < maximal_l:
+                    # A momentary spike to left channel inherited by right
+                    maximal_r = maximal_l
+                if maximal_l < maximal_r:
+                    # A momentary spike to right channel inherited by left
+                    maximal_l = maximal_r
+            else:
+                # Mono - processing all data
+                amp_l = None
+                amp_r = None
+                amp = Amplitude.from_data(data)
+                gap = amp.value      # For signal test below.
+                if amp > maximal:
+                    maximal = amp
+
+            # New code January 23, to reset next song's maximal during gap
+            if gap == 0.0:
+                reset_baseline_count += 1
+                if reset_baseline_count == 10:
+                    maximal = Amplitude()
+                    maximal_l = maximal_r = maximal
+                    # print('maximal reset', maximal.value)
+            else:
+                reset_baseline_count = 0
+
+            # January 24, 2021 separate left and right channels
+            if parameter == 'stereo':
+                amp_l.display(scale=200, mark=maximal_l, fn=VU_METER_LEFT_FNAME)
+                amp_r.display(scale=200, mark=maximal_r, fn=VU_METER_RIGHT_FNAME)
+            else:
+                # Mono processing one channel combined sound
+                amp.display(scale=200, mark=maximal, fn=VU_METER_FNAME)
+
+    finally:
+        stream.stop_stream()
+        stream.close()
+        audio.terminate()
+
+
+if __name__ == "__main__":
+    main()
+
+# End of vu_meter.py