Import FSK decoder from another project of mine

fsk-decode.py

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+# FSK-decode
+# For Python 3
+# By Zoe Blade
+
+# (Hopefully) converts a .wav file into a demodulated .bin file
+
+import struct # For converting the (two's complement?) binary data to integers
+import sys # For command line arguments
+import wave # For .wav input and output
+
+# Set sensible defaults
+amplitudeThreshold = 1024 # This has to be a number between 1 and 32767
+frequencyThreshold = 1600 # This should be a number between 1 and the waveform's sample rate
+baudRate = 300 # This should be a number between 1 and the waveform's sample rate
+inputFilenames = []
+
+# Override the defaults
+for argument in sys.argv:
+	# Override the filename
+	if (argument[-4:].lower() == '.wav'):
+		inputFilenames.append(argument)
+		continue
+
+	# Override the threshold
+	if (argument[:22] == '--amplitude-threshold='):
+		argument = int(argument[22:])
+
+		if (argument > 0 and argument < 32768):
+			amplitudeThreshold = argument
+			continue
+		else:
+			print('The amplitude threshold must be an integer between 1 and 32767')
+			exit()
+
+	if (argument[:22] == '--frequency-threshold='):
+		argument = int(argument[22:])
+
+		if (argument > 0 and argument < 44100):
+			frequencyThreshold = argument
+			continue
+		else:
+			print('The frequency threshold should be an integer between 1 and the sample rate')
+			exit()
+
+	if (argument[:12] == '--baud-rate='):
+		argument = int(argument[12:])
+
+		if (argument > 0 and argument < 44100):
+			baudRate = argument
+			continue
+		else:
+			print('The baud rate should be an integer between 1 and the sample rate')
+			exit()
+
+if (len(inputFilenames) == 0):
+	print("""\
+Usage:
+python3 fsk-decode.py [option...] input.wav
+
+Options: (may appear before or after arguments)
+	--amplitude-threshold=foo
+		set the cutoff point between signal and noise (default is 1024, any number between 1 and 32767 is valid)
+	--frequency-threshold=foo
+		set the cutoff point between low and high frequency, in Hertz (default is 1600, any number between 1 and the sample rate is valid)
+	--baud-rate=foo
+		set the baud rate, in Hertz (default is 300, any number between 1 and the sample rate is valid)
+	""")
+	exit()
+
+# Cycle through files
+for inputFilename in inputFilenames:
+	outputFilenamePrefix = inputFilename[:-4]
+	outputFilenameNumber = 0
+
+	try:
+		inputFile = wave.open(inputFilename, 'r')
+	except:
+		print(inputFilename, "doesn't look like a valid .wav file.  Skipping.")
+		continue
+
+	print("Converting", inputFilename, "to pulse waveform")
+
+	framerate = inputFile.getframerate()
+	numberOfChannels = inputFile.getnchannels()
+	sampleWidth = inputFile.getsampwidth()
+
+	pulseWaveform = {}
+
+	for iteration in range(0, inputFile.getnframes()):
+		allChannelsAsBinary = inputFile.readframes(1)
+		allChannelsCurrentlyBeneathThreshold = True
+
+		for channelNumber in range (numberOfChannels):
+			channelNumber = channelNumber + 1
+			channelStart = (channelNumber - 1) * sampleWidth
+			channelEnd = channelNumber * sampleWidth
+			channelAsInteger = struct.unpack('<h', allChannelsAsBinary[channelStart:channelEnd])
+			channelAsInteger = channelAsInteger[0]
+
+			if (channelAsInteger >= amplitudeThreshold):
+				pulseWaveform[iteration] = True
+			else:
+				pulseWaveform[iteration] = False
+
+			break # Only pay attention to the first (mono or left) channel
+
+	print("Demodulating", inputFilename)
+
+	frequencies = {}
+	highFrequency = False
+	falses = 0
+	lastSampleValue = 0
+
+	for sampleAddress, sampleValue in pulseWaveform.items():
+		if (lastSampleValue == False and sampleValue == True):
+			# Rising tip of waveform.  Time to measure it.
+			if (framerate / falses > frequencyThreshold):
+				# It's the highest of the two expected frequencies
+				highFrequency = True
+			else:
+				# It's the lowest of the two expected frequencies
+				highFrequency = False
+
+			falses = 0
+		else:
+			falses = falses + 1
+
+		lastSampleValue = sampleValue
+		frequencies[sampleAddress] = highFrequency
+
+	print("Grouping blocks of", inputFilename, "at baud rate intervals")
+
+	data = []
+
+	# 1 (second) / baud rate * sample rate = samples per block
+	# Therefore sample rate / baud rate = samples per block
+	blockSize = int(framerate / baudRate)
+
+	lowFrequencyTally = 0
+	highFrequencyTally = 0
+
+	for sampleAddress, highFrequency in frequencies.items():
+		if highFrequency == True:
+			highFrequencyTally = highFrequencyTally + 1
+		else:
+			lowFrequencyTally = lowFrequencyTally + 1
+
+		if sampleAddress % blockSize == 0:
+			# Block division!
+			if (highFrequencyTally >= lowFrequencyTally):
+				data.append(True)
+			else:
+				data.append(False)
+
+			lowFrequencyTally = 0
+			highFrequencyTally = 0
+
+	print("Truncating", inputFilename)
+
+	truncatedData = []
+	copying = False
+
+	for bit in data:
+		if bit == True:
+			copying = True
+
+		if copying == True:
+			truncatedData.append(bit)
+
+	print("Converting", inputFilename, "to binary")
+
+	rawData = []
+	byte = 0
+	position = 0
+
+	for bit in truncatedData:
+		byte = byte | bit << position
+		position = position + 1
+
+		if position == 8:
+			rawData.append(byte)
+			byte = 0
+			position = 0
+
+	rawData = bytes(rawData)
+	outputFilename = inputFilename[:-4] + '.bin'
+	print("Writing ", outputFilename)
+
+	try:
+		outputFile = open(outputFilename, 'wb')
+	except:
+		print("Could not write to", outputFilename, "- skipping")
+		continue
+
+	outputFile.write(rawData)
+	outputFile.close()
+
+	print(inputFilename, "finished converting")