Abstract: A novel technique for embedding a reversible watermark into digital media files, and then removing this watermark, in whole or in part, at some later date, without access to the original media file, which may consist of such media types as audio, image, video, 3-D and the like; such watermarks being primarily intended for, though not limited to, the introduction by a reversible mathematical operation of perceptually significant elements, including but not limited to pseudorandom noise, such that the degraded media is suitable merely for demonstration or trial purposes, and with the watermark resistant to removal without proper authorization; but with authorization, can then be removed from the media file to prepare it for its ultimate high-quality use.

Abstract: A novel process and system for flexibly adding supplemental digital program content such as, for example, transactional advertising content, games, polls, contests, interactive music videos, and e-commerce content generally and the like, into pre-prepared digital media files, such as an MP3 audio file or the like, for playback by digital playback apparatus, wherein the pre-prepared media file is modified by embedding therein executable code representing such supplemental program content, and enabling the playback apparatus to decode and execute the presentation of the supplemental program material as an addition to the playback of the pre-prepared media file content.