Ubuntu's libfaac AAC encoder causing concern
Problems with the licensing of the faac library could lead to it having to be removed from Ubuntu's distribution or moved to the "restricted" repositories where license encumbered codecs are kept. Libfaac is used to encode audio into the AAC format, which is used alongside a range of video formats to provide a soundtrack. The issue, reported on OMGUbuntu, arises due to some files in faac being under a non-free licence, despite the package being licensed as LGPL. Although the problem is not restricted to Ubuntu but to many Linux distributions which may include libfaac, the issue is more pronounced for Ubuntu as it approaches the release of a Long Term Support version of the Debian derived distribution.
The problem had been raised as a bug entry last year in the Launchpad system used for tracking Ubuntu bugs, itself raising an issue from the FFmpeg developers. As the release of Ubuntu 10.04 LTS approaches, the issue has resurfaced. An evaluation on the FFmpeg developers mailing list suggests that a number of files have unknown or conflicting lineage.
One solution would be to remove libfaac from the distribution, but as is pointed out in the bug comments this would affect a number of packages, including DivX and H.264 encoders, GStreamer's bad plug-ins, MEncoder, OGMRip and MPlayer. Although the packages could be compiled to not use libfaac, according to another comment, it's removal would mean that Ubuntu 10.04 would ship without "any usable AAC encoder". The loss would not affect decoding AAC audio files and streams as these are handled by the libfaad decoder.