def embed_LSB(carrierFile,payloadFile,outFile):
"""Embed a message in the carrier audio using modified LSB coding
Returns audio data with the embedded payload
Parameters:
carrierFile - the name of the carrier audio file
payloadFile - the name of the payload file
outFile - the name of the file to which the package will be written
"""
from amm import wavread,wavwrite
_logInfo("Encoding...")
# read in the carrier file
samples,params = wavread(carrierFile,bSplit=False)
samples = samples.tolist()
sampleLength = len(samples)
# Read the payload in and store it as a list of integers
payload = None
payloadData = None
try:
payload = open(payloadFile, 'rb')
payloadData = bytesToInts(payload.read())
except (IOerror) as err:
_logError("Error reading from file '%s'" % payloadFile)
raise err
finally:
if payload: payload.close()
payloadDataLength = len(payloadData)
payloadSizeData = bitsForInt(payloadDataLength,size=32)
payloadSizeDataLength = len(payloadSizeData)
_logDebug("Payload is %d bits" % payloadDataLength)
_logDebug("That is %f of # of samples" % (float(payloadDataLength)/sampleLength))
# Verify that the payload is reasonably sized
if (payloadDataLength > (sampleLength - 32)):
err = InvalidSize("Payload is too large.")
_logError("Can't embed the payload into the carrier")
raise err
# Embed payload size into first 32 bits of package
for i in xrange(32):
if (samples[i] % 2 != payloadSizeData[i]):
samples[i] += 1
# Embed the payload in the carrier
for i in xrange(payloadDataLength):
if (samples[i+32] % 2 != payloadData[i]):
samples[i+32] += 1
# Write the package to file
wavwrite(outFile,params,stream=samples)
_logInfo("Success!")
xlabel(r'n (samples)')
title(r'Step response')
subplots_adjust(hspace=0.5)
# Read in audio file
samples, params = wavread("almostjungle1.wav", bSplit=False)
samples = samples.tolist()
sampleLength = len(samples)
sampleRate = params[2]
filter_order = 20
coefficients = signal.firwin(filter_order, cutoff=0.3, window="hamming")
#Frequency and phase response
#mfreqz(a)
#show()
#Impulse and step response
#figure(2)
#impz(a)
#show()
filtered_samples = []
# pass signal through filter
for i in range(sampleLength):
products = []
for j in range(filter_order):
products.append(samples[i] * coefficients[j])
filtered_samples.append(sum(products))
wavwrite("out.wav", params, stream=filtered_samples)
for i in xrange(0,len(left),windowSize):
delay = zeroDelay if payloadData[i % payloadSize] == 0 else oneDelay
stop = min(i+windowSize,min(len(left), len(right)))
for j in xrange(i,stop):
embedded_left[j] = (left[j] if j < delay
else left[j] + ECHO_SCALE*left[j-delay])
embedded_right[j] = (right[j] if j < delay
else right[j] + ECHO_SCALE*right[j-delay])
=======
embedded_left = iFFTs(leftFFTs,timeStep)
embedded_right = iFFTs(rightFFTs,timeStep)
>>>>>>> other
_logInfo("Embedding complete. Writing file...")
wavwrite(outFile,params,leftStream=embedded_left,rightStream=embedded_right)
def decode2(packageFile,outFile):
from amm import wavread
_logInfo("Decoding...")
left,right,params = wavread(packageFile)
sampleRate = params[2]
sampleLength = params[3]*2
windowSize = int(floor(sampleLength*0.001/2))
_logDebug("window size is %d samples" % windowSize)
payloadSizeBits = int(floor(sampleLength*0.001,2))
_logDebug("First %d bits represent size of payload" % payloadSizeBits)
subplots_adjust(hspace=0.5)
# Read in audio file
samples,params = wavread("almostjungle1.wav",bSplit=False)
samples = samples.tolist()
sampleLength = len(samples)
sampleRate = params[2]
filter_order = 20
coefficients = signal.firwin(filter_order, cutoff=0.3, window="hamming")
#Frequency and phase response
#mfreqz(a)
#show()
#Impulse and step response
#figure(2)
#impz(a)
#show()
filtered_samples = []
# pass signal through filter
for i in range(sampleLength):
products = []
for j in range(filter_order):
products.append(samples[i] * coefficients[j])
filtered_samples.append(sum(products))
wavwrite("out.wav",params,stream=filtered_samples)
