Pulses from .wav

gistfile1.py

import wave
import sys

if len(sys.argv) > 2:
	path = sys.argv[1]
else:
	path = "/home/whoeverest/code/klima-reverse/16c.wav"

wav = wave.open(path)
	
frames = map(ord, wav.readframes(wav.getnframes()))

# Merge frames in pairs: frame[0] * frame[1], frame[2] * frame[3] etc.
frames = [frames[i] * frames[i+1] for i in range(0, len(frames), 2)]

# Normalize: 1 if above half strength, 0 if under.
half_strength = max(frames) / 2
frames = [1 if frame > half_strength else 0 for frame in frames]

# Detect changes: from 1 -> 0 or from 0 -> 1.
changes = [i for i in range(len(frames) - 2) if frames[i] != frames[i+1]]

def find_pulses(changes, threshold=47, start=0):
	level = start
	sequence = []
	for i in range(len(changes)):
		if i == len(changes) - 2:
			break
		if changes[i+1] - changes[i] > threshold:
			# Pulse: (level, start, end)
			sequence.append((level, changes[i], changes[i+1]))
		level = 1 if not level else 0
	return sequence

# We don't know the threshold, so try out different
# values and see if we can spot a pattern.
start, end = 45, 50
sequences = [find_pulses(changes, thr) for thr in range(start, end)]

for seq in sequences:
	print seq