Combine sounds into one (v2)

# combine all individual graph sounds into one waveform (v2)
# This version will get rid of short glitch sounds.

import soundfile as sf
import numpy as np

idle_duration = 0.1
graph_duration = 5.0
min_duration = 1.0

data, samplerate = sf.read('graphs.wav')
graph_samples = int(graph_duration*samplerate)

# process each data point
last_time = 0
triggered = False
start_points = []
end_points = []
for i, samp in enumerate(data):
    cur_time = i / samplerate

    if np.abs(samp[0]) > 0.001 or np.abs(samp[1]) > 0.001: # sound detected
        if not triggered: # this is a new chunk
            start_points.append(i)
            triggered = True
        last_time = cur_time

    elif triggered and cur_time - last_time > idle_duration: # silence detected
        end_points.append(i)
        triggered = False

# in case the last end point is not detected, add one.
if len(start_points) != len(end_points):
    end_points.append(len(data[0]) - 1)

# new combined graph sound
arr = np.zeros((graph_samples, 2))

graphs = 0
for i, point in enumerate(start_points):
    if end_points[i]/samplerate - point/samplerate < min_duration:
        continue
    arr += data[point:point+graph_samples]
    graphs += 1
print(f'{graphs} graphs detected')
arr /= graphs # normalize

sf.write('graphs_combined.wav', arr, samplerate)