Audio Watermarking Tools 1 (AWT1) - 2 bytes payload max
Audio Watermarking Tools 1 (AWT 1) of www.audiowatermarking.info are software utilities for embedding (and extracting) short data payload within audio streams (wave files). The tools are distributed as a package of console utilities running on Microsoft Windows, Apple Mac OS X and Linux/*nix systems. The watermark is extremely robust. It survives almost all kinds of audio conversions: transcoding using MP3, Ogg Vorbis, air transducing, etc.