Audible hidden watermarks? Would like to compare .AA files from Audible.

[RevRhubar]

I was wondering if anyone knew if Audible insert hidden customer-identifying watermarks into their audio books? I.e. when you download an .aa file is your account number or something merged into the file (as in Steganography)? So if a DRM-stripped version of the file ever found itself onto a p2p network Audible could trace the original purchaser of the file.

Not that I have any intention of uploading my files onto the Internet, but I like to convert them into old fashioned CDs (which are obvioulsy DRM free) and if they were lent/stolen and then illegally distributed, I could be liable.

One way to find out would be to get two copies of the same file purchased from two different Audible accounts and see if the files were identical (rather that sharing the actual .aa files we could each use a program to compute a 'hash' or something on each file and then compare the hashes).
Let me know if anyone is interested in doing this.

Since DRM protection is used for Audible, the company probably uses different DRM keys for its customers, so the .AA files are different. Content providers can also use different ID3 tags in .AA files to identify customers. So to verify whether Audible uses watermarks or not, you need to remove DRM protection and make sure the files have identical ID3 tags. It is better to remove DRM protection with the same software. Then you can compare DRM-free files with the identical ID3 tags.

[wavy1977]

Yes, audible puts a digital watermark in the audio files. Even if you remove DRM and convert the audiobook to WAV files, the watermark is still there. We can thus say audible uses watermarked audiobooks even in drm-free solutions.