When German audio engineers developed the MP3 format in the early 1990s, they unwittingly created the currency of online music piracy - song files that could be copied freely and downloaded swiftly. MP3 Music fans embraced the format, but it was snubbed by record labels and online music services because there was no way to stop MP3s from being bootlegged.

Now Thomson, the French company that distributes MP3 technology, is trying to make amends to the music industry. It’s adding electronic locks that a record label can use to limit the number of times a song can be duplicated onto CDs or portable devices.

Thomson, however, may have a tough time finding an audience for this version.

The online music market already is crowded with competing secure formats from Microsoft Corp., Apple Computer Inc., RealNetworks Inc. and Sony Corp. Their incompatibility gives record label executives heartburn, and Thomson’s move adds a fifth format that doesn’t work with any of the others. Plus, MP3 songs encoded in the new format won’t work on many older digital music players for which the original MP3 is the lingua franca.