Audio Watermarking - What is typically embedded?
Research papers or textbooks won't delve into the specifics - they just assume you have a stream of binary data that needs to be reliably and undetectably embedded into the audio file.

What this bitstream is actually going to be is application dependent. It could be:


Digital rights management applications: A short serial number identifying the individual transaction in which the audio file has been sold. Given the small size (a hundred bits) of this information, it is typically repeated over and over the file to maximize the probability of recovering it.
Metadata management: Metadata such as artist name, song title, or even lyrics.
Proper steganography: Any secret data you want to share with the recipient of the audio file - without an eavesdroppers suspecting that you are exchanging anything other than music. This can be a text-file, an image - any binary data.
Informed source separation: Any information about the individual sources the audio file is made of, that would subsequently help in recovering these individual sources.
Second-screen interactive TV applications: These application allow a device such as a smartphone or a toy to display secondary information synchronized with a TV show. To allow the synchronization, the audio signal of the show contains a regular watermark containing a show identifier and time stamp.