How many types for hiding audio in an audio file are there? And would we be able to realize or hear an hidden audio message in a song in all types of steganography?
closed as too broad by Philipp, Anders, Matthew, Xander, WhiteWinterWolf Jun 22 '16 at 12:09
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An MP3 file consists of many frames. A frame is a piece of data of about 1000 bytes long, with a little sound data in it. Each frame consists of a header and some data. The header contains the bitrate for the frame, whether the sound is in stereo, and so on. A player plays a file by looking for these headers, decoding the frames and playing the sound.
You can put any data that does not look like a frame header in between the frames and the file will still play correctly. The player simply ignores your data and searches for the next frame when playing. By hiding data in between the frames, the sound is not modified at all.
Another way is to use some bits in the header to hide the message. The "private" bit, for example, is unused by most applications and can be used to store a bit of data. This would go unnoticed when playing the file.
If you want to hide data in the sound data itself, you have to change the sound data a bit to contain your message. Whether this is audible depends on how much the original data is changed, and whether it is done with knowledge of the MP3 specification.