Inaudible watermarking of audio files

Hello,

Not sure if this is the proper thread, but I was wondering if anyone knew of a decent way of watermarking audio files for the purpose of giving out pre-release copies from a record label to promoters and reviewers.

The goal being the ability to identify anyone leaking the files ahead of the release date in order to remove them from the list of people being given pre-release copies the next time around (as opposed to any sort of enforcement action.) The tracking/logistics behind it aren't necessarily important, just the watermarking ability.

Ideally, the watermark would be both inaudible as well as able to survive being re-encoded.

If anyone knows of something along these lines, it'd be much appreciated.

Thanks

- B