The short answer to your question is 'no.'  The MP3 specification has no provision for watermarking.  The RIAA might feel more kindly towards MP3 if it did.  You might be able to place something in an ID3 tag, but it likely would not be worth the bother.  You could distort the sound in some way, or include a few invalid frames.  Whether or not this is inaudible I will let you decide.  If you need some sort of copy protection or digital rights management Microsoft's Windows Media could be more appropriate.

ok clear answer...is there a free/cheap tool that includes inaudible watermarking into audio that survives the mp3 encoding? i know there are some very expensive ones that do just that..but i don't have the money to purchase those tools because it's all small-scale operations..

Read this too: http://www.janisian.com/article-internet_debacle.html
Even artists know, so should you.

A couple of possible suggestions:

  1) You could first take your "master" MP3s (with no tags/additions whatsoever) and create an MD5 checksum for each. That way, even if someone added a tag, as long as the internal MP3 structure was not corrupted you could simply strip the tags from suspicious files and compare them to your checksums. Of course, you would also have to allow for the possibility of someone using MP3Gain to alter the relative volume of your MP3s, in which case you would need to know the original volumes of your files and also check the volume of suspicious files, adjusting accordingly.

  2) If you are using L.A.M.E., you might be able to insert a spurious entry into the L.A.M.E./Xing tag. The advantage to this method is that the L.A.M.E. tag is going to survive MP3Gain'ing, but you would need to use a file-parsing program to search for your edited tags.

  But - and I mean this with the best of intentions - I doubt anyone here would ever consider buying an album they knew was from an MP3 source. If it is your own record label, and recordings to which you own the copyright, you can of course do as you wish... but think about your customers. Is this truly what they would want, or be willing to purchase?

    - M.

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ok clear answer...is there a free/cheap tool that includes inaudible watermarking into audio that survives the mp3 encoding? i know there are some very expensive ones that do just that..but i don't have the money to purchase those tools because it's all small-scale operations..

No.

Because it will be defeated. See: http://cryptome.org/sdmi-attack.htm

You can't prevent a copy. If you mark it, the people will learn to remove the marks. Your attempts will only make your own costs go higher, all in vain. Time to redesign your business strategy. Nothing personal.

There is no point in working against your consumers needs, open the doors, see the reality. Time has changed. Make sure your clients get the message too, they will anyway, either the easy or the hard way. You choose.

Read this too: http://www.janisian.com/article-internet_debacle.html
Even artists know, so should you.

Will you treat your own customers as friends or enemies? Choose.
Will you lie to your client and sell them a system you know is going to be defeated?.

Watermarking mp3 files is possible, and it's free. See:  http://www.cl.cam.ac.uk/~fapp2/steganography/mp3stego/

However I can see various problems about this approach:
- the mp3 encoder within mp3stego is very basic, thus you'll not get great sound quality,
- the hidden data will be destroyed if you transcode the mp3 file.
- the fact that mp3stego was used for encoding, should be fairly obvious when analyzing

The advantages of having a steganography-aware encoder:
- the original WAV data is untouched
- the encoder can take psychooacoustics into account to seamlessly store the hidden data.

I think the hidden data is stored as very small "details" in the MDCT coefficients of several (all?) frames of the mp3 file. If it's well done it could survive a mp3trim, but not a transcoding.

So in short, if you're in desperate need for steganography you can use this.. but if you're an audiophile, I suggest you use LAME and one of the following tricks:
- Make every mp3 encoding "unique", which means, encode each mp3 from a source file which has some bits swapped (64 changed bits in total should be enough). Keep track of the checksums of a few mp3 frames (or maybe the checksums of the bare mp3 data without tags and headers). Then distribute the files.

If people transcode (ie: re-encode) your files, you're screwed anyway. But otherwise, except for the obvious hate that file-sharing people will have for you, you can try it 

Since many people re-tag their mp3's (and windows media player even does this automatically sometimes), this will require probably require some development for the integrity checking.

IMHO adding stego or inaudible frequencies (see http://www.hydrogenaudio.org/forums/index....t=ST&f=1&t=1573 ) is not an audiophile acceptable solution

3. randomly modify a copy of the mp3 very subtly: single step volume adjustment or reencode a single frame.

Olafmol, if you want to automate things under windows, may I suggest you try batch files, using a command interpreter such as JPsoftware's 4DOS/4NT ?

I suggest you try the LAME "--scale" method first.

Encode 3 WAV files to MP3 using 3 slightly different scaling values (for example 0.90; 0.91; 0.92), then decode them and calculate each RMS value in Matlab (or maybe CoolEdit Pro). You should be able to distinguish between the 3 mp3 files, and they should sound identical of course.

Edit:  When you know the difference is there, you can try programming the measuring tool in quickbasic or something 

There is no point in working against your consumers needs, open the doors, see the reality. Time has changed. Make sure your clients get the message too, they will anyway, either the easy or the hard way. You choose.

Will you treat your own customers as friends or enemies? Choose.
Will you lie to your client and sell them a system you know is going to be defeated?.