"In its HTML5 support, IE9 will support playback of H.264 video only," said Dean Hachamovitch, Internet Explorer general manager, in a blog post. "H.264 is an industry standard, with broad and strong hardware support."
But H.264 isn't accepted by the open source community because it is encumbered by patents. That's why Mozilla doesn't support H.264 in Firefox.
Use of the H.264 video codec requires a license from the MPEG LA, a group that manages pools of patents on behalf of participating companies.
Microsoft is one of many licensors of patents managed by MPEG LA and as such shares in the licensing royalties collected from H.264 video licensees. Apple, another supporter of H.264, is also an MPEG LA licensor.
Supporters of open source software immediately voiced their distaste for Microsoft's decision on the company's blog. Well over 100 comments have been posted the space of a day, most of which are critical.
Anticipating such objections, Hachamovitch said that various unnamed free alternatives -- presumably Ogg Theora -- are not as free of licensing risks as open source supporters claim.
"Other codecs often come up in these discussions," he said. "The distinction between the availability of source code and the ownership of the intellectual property in that available source code is critical. Today, intellectual property rights for H.264 are broadly available through a well-defined program managed by MPEG LA. The rights to other codecs are often less clear, as has been described in the press."
Ogg supporters characterized this statement as FUD -- expressions of fear, uncertainty, and doubt used to enhance the perception of risk associated with a particular choice.
The argument may be resolved, at least in part, next month, when Google is expected to open source the VP8 video codec that it gained through its acquisition of video technology firm On2.
In theory, this would provide a free video codec, unencumbered by potential patent liability, one that's acceptable to everyone. Then again, if this argument is really about control and money, simply making VP8 available for free may not be enough to sway Microsoft, or others with a vested interest in H.264 like Apple.