I've read comments on the Web suggesting that since the MPEG-LA's patent licensing documentation only mentions playback products that are "sold", the MPEG-LA doesn't expect software that is given away at zero cost to need a license. Intrepid LWN reader Trelane actually bothered to ask them, and got a response. Here it is.
The most important part of the response:
In response to your specific question, under the Licenses royalties are
paid on all MPEG-4 Visual/AVC products of like functionality, and the
Licenses do not make any distinction for products offered for free
(whether open source or otherwise).
I would also like to mention that while our Licenses are not concluded
by End Users, anyone in the product chain has liability if an end
product is unlicensed. Therefore, a royalty paid for an end product by
the end product supplier would render the product licensed in the hands
of the End User, but where a royalty has not been paid, such a product
remains unlicensed and any downstream users/distributors would have
Therefore, we suggest that all End Users deal with products only from
licensed suppliers. In that regard, we maintain lists of Licensees in
Good Standing to each of our Licenses at http://www.mpegla.com.
In other words, if you're an end user in a country where software patents (or method patents) are enforceable, and you're using software that encodes or decodes H.264 and the vendor is not on the list of licensees, the MPEG-LA reserves the right to sue you, the end user, as well as the software vendor or distributor.