Google fired a shot across Apple's bow Wednesday and considering the way things have been going Apple will probably seek to return fire in the not-too-distant future with an armor-piercing lawsuit.

The latest fray started when Google got up at the Google I/O developers conference - like it was widely expected to do - and open sourced VP8, the video codec it got when it acquired On2 Technologies, the video compression house, in February for about $125 million.

VP8 will try to displace H.264, the proprietary codec that Apple and Microsoft are invested in.

VP8 is now part of a thing called the WebM project, which also includes the open source Ogg Vorbis audio format, and a container format based on a subset of the open source Matroska multimedia container.

Needless to say, WebM is royalty-free and already has the support of the majority of the browser community: the Mozilla Foundation's open source Firefox browser, which Google still supports financially, Opera, Google's own Chrome and at the last minute Microsoft's upcoming Internet Explorer 9, due in, oh, say, 2011.

Well, at least it will allow playback if users install the codec themselves and Ars Technica thinks that's to avoid any patent problems like IBM and Linux. Microsoft is sticking with H.264 otherwise.

What Microsoft's gonna do about VP8's implicit challenge to Silverlight may turn out to be a horse of another color.

Given its high-profile falling out with Apple Abode's also promising to support VP8 in its proprietary and ubiquitous Flash, which would bring the widgetry to IE and Safari users despite what Microsoft and Apple might do. Otherwise, Flash is widely regarded as a dead man walking.

Google also means to create WebM plug-ins for QuickTime and DirectShow and has set Android support for the so-called Gingerbread release planned for Q4

H.264 lives at MPEG LA, a licensing operation in Denver that collects royalties for the patent pools it represents. Both Microsoft and Apple have IP in H.264, but H.264 (which is on its way to becoming H.265) is free for browsers to use for the next five years. After that the royalty picture is supposed to change.

It is widely considered likely that VP8 may infringe on H.264 patents and, if not H.264, then somebody else's.

In a recent widely disseminated e-mail exchange Apple CEO Steve Jobs reminded Free Software Foundation Europe executive Hugo Roy that "All video codecs are covered by patents. A patent pool is being assembled to go after Theora and other ‘open source' codecs now. Unfortunately, just because something is open source, it doesn't mean or guarantee that it doesn't infringe on other patents. An open standard is different from being royalty-free or open source."

Google offers no indemnification for using its widgetry (doing so would be like painting a great big bull's-eye on its back) so Apple (and perhaps the Hollywood set since VP8 doesn't support DRM) could bide its time and pick off one of the weaker sisters like it's evidently trying to do by suing HTC for Android patent infringement.

Naturally Google is taking the position that it doesn't infringe apparently because earlier versions of the thing were never called to account. It may not even know whether it does or not.

There's a side-by-side comparison of H.264 and VP8 at www.streamingmedia.com/Articles/Editorial/Featured-Articles/First-Look-H.264-and-VP8-Compared-67266.aspx which concludes that H.264 "offers better quality, but the difference wouldn't be noticeable in most applications."

Google claims that "VP8's efficient bandwidth usage will mean lower serving costs for content publishers and high-quality video for end users. The codec's relative simplicity makes it easy to integrate into existing environments and requires less manual tuning to produce high-quality results. These existing attributes and the rapid innovation we expect through the open development process make VP8 well suited for the unique requirements of video on the web."

A developer preview of WebM and VP8 including APIs, source code, specs and encoding tools is available at www.webmproject.org.

Google admits the widgetry is incomplete and hogs processor resources but it expects better visual quality and optimized performance in a pending official release. GPU acceleration may be off in the distance; ARM, AMD, Nvidia, Broadcom and Qualcomm are supporting WebM.

The current VP8 spec is final.

Digital video expert Jason Garrett-Glaser, however, calls the spec "imprecise, unclear and overly short," "a pile of copy-pasted C code" that's nowhere ready for prime time. He also told tgdaily it copies a lot from H.264, "way too much for anyone sane to be comfortable with it no matter whose word is behind the claim of being patent-free."

For its part Google is already lacing YouTube videos larger than 720p with VP8 and YouTube is supposed to represent 40% of the video on the Internet. It's still using Flash too.

VP8 is governed by a new Google-made BSD-style license so it can be used in both proprietary and open source software. It does not require that code changes be open sourced. It grants patent rights that terminate if patent litigation is filed against VP8 or its children. The license hasn't been submitted to OSI.