def decode_LSB(packageFile,outFile):
"""Decode the embedded message from the given package using modified LSB coding
Returns the binary embedded message
Parameters:
packageFile - the name of the package audio file
outFile - the name of the file to which the decoded payload will be written
"""
from amm import wavread
_logInfo("Decoding...")
samples,params = wavread(packageFile,bSplit=False)
# the first 32 bits encode the size of the payload
payloadSizeChunk = samples[0:32]
payloadSize = intForBits([i % 2 for i in payloadSizeChunk])
_logDebug("Payload size = %d" % payloadSize)
# check that the encoded payload size is not too large
if (payloadSize > (len(samples) - 32)):
err = InvalidSize("Specified payload size is too large")
_logError("Invalid input for decoding")
raise err
payloadSegment = samples[32:32+payloadSize]
payload = intsToBytes([i % 2 for i in payloadSegment])
out = None
try:
out = io.open(outFile,'wb')
out.write(bytearray(payload))
out.flush()
except IOError as err:
_logError("Error writing out decoded data")
raise err
finally:
if out: out.close()
_logInfo("Success!")
## DECODING IS NOT COMPLETE YET
=======
from apm import FFTs,iFFTs
leftFFTs = FFTs(left,WINDOWSIZE,timeStep)
rightFFTs = FFTs(right,WINDOWSIZE,timeStep)
decoded_data = []
for i in range(len(leftFFTs)):
mag1 = np.mean([abs(leftFFTs[i][f]) for f in FREQ1])
mag0 = np.mean([abs(leftFFTs[i][f]) for f in FREQ0])
bit = 0 if mag0 > mag1 else 1
decoded_data.append(bit)
payload = intsToBytes(decoded_data)
out = None
try:
out = io.open(outFile,'wb')
out.write(bytearray(payload))
out.flush()
except IOError as err:
_logError("Error writing out decoded data")
raise err
finally:
if out: out.close()
_logInfo("Success!")
>>>>>>> other
