Audio Processing with Python-Decoding Audio File

The aim of this project is to use the python thinkdsp library to breakdown and decipher an encoded audio file, there are 3 exercises each with varying levels of complexity.

• A encoded Audio file will be provided and the goal is to retrieve the hidden message buried at each complex layer

Excercise 3.1 - Hidden text msg among audio file

A hidden text message is buried among the audio file, and a decoy music is used to mask the original message. Here are the steps to retieve the message:

• Convert the audio file into a byte array
• Use LSB method and get the lowest bit of the audio frame
• Convert the extracted bytes into a string text

Excercise 3.2 - Secret passcode

A secret audio message is recorded at a lower frequency than humans are able to hear. The message is also split across 3 audio files sound2.wav, sound3.wav and sound4.wav for added secrecy.

The method in solving this is quite straight forward:

• First combine the 3 audio files into one single file, lets call it sound5.wav and read from that
• The file will under go a high-pass filter to remove all sounds above a certain freq
• Then i will use demodulation to tune the sound into something recognizable

Excercise 3.3 - Encode Message

Now I have to use the method I have learnt above and encode my own secert message using the techniques as an example.