将MP3标记为复制遏制

Question

As a copy determent for my mp3-files (handed out individually or over web shop) I thought about marking the files each by cart-code-token, which I have to keep for legal reasons anyways.

Contra:
With basic understanding of the mp3 codec I came up with the idea of putting the cart code in one sample or spreading the info over more of them. One or some samples will be destroyed this way if the file is played, but it won't be even noticable in regular sampling rates (128kbps and above). No protection after harsh downsampling, though.

Pro: Under circumstances even in waveform you yould possibly still determine the code. In any way information about marking the file could have some impact on users behavior. At least it could provoke a second thought about passing the file on as it is.

How would you suggest me to imprint the code onto the mp3 audio stream? I would do it by file manipulation via PHP, if possible while serving the file for download.

Answer 1

you haven't discovered anything new: that's watermarking at its finest :-)

there are many MP3 watermarker program out there which imprint your data all over the audio stream. Such watermarks can resist file copy (obviously), upsampling, downsampling (to a given degree), audio trimming and even analog re-recording

check wikipedia: http://en.wikipedia.org/wiki/Steganography#Implementations

section 3 of this site site is on audio: http://www.binary-universe.net/ same author did a project on codeplex.

these also do audio: StegHide mpeStego

and this one: https://github.com/jcelerier/watermarking/tree/master/src/libwatermark