It's far worse than you can possibly imagine. I have a friend who a while back wanted to make an iPhone app that could play streaming music from various websit

It's far worse than you can possibly imagine. I have a friend who a while back wanted to make an iPhone app that could play streaming music from various websites (for formats and protocols the iPhone couldn't natively handle). Everything was looking good until they went to talk to Real. Real didn't even have an implementation for their platform, so like everyone else sane, they simply used the open source libavcodec, from the ffmpeg project, to decode the audio formats they needed (Real, Windows Media, etc). But they figured that since Real Audio is a completely proprietary format, it would be best to get a license from Real anyways. So they call up Real and ask for a license and so forth. Everything's going great until the guy asks them about the software they'll be using... ... upon which point the guy goes into an almost murderous rampage about how ffmpeg is "stealing the code" and basically tells them that if they use ffmpeg at all, anywhere in their company, Real won't license to them. And why? Because ffmpeg--legally--reverse-engineered Real Audio and Real Video. The latter of which was the primary point of contention--and the great irony of it all is that Real Video itself is actually a blatant ripoff of H.264, and most of the "reverse engineering" consisted of reading early (publicly available!) drafts of the specification.