Just when the H.264 video codec is starting to take over a large portion of new Web videos, along comes Google to shake things up again. Today, along with Mozilla and Opera, it is launching the WebM Project, an open, royalty-free codec that can run in HTML5 browsers without the need for Flash.

Up till now, the battle between Flash and HTML5 video has centered around the H.264 codec, which is gaining broad adoption. Apple supports H.264 in all of its devices such as iPads and iPhones, and it is one of the technical reasons Steve Jobs cites for why there is less and less need to support Flash. H.264 is a modern codec, fast and light. It’s great except for one thing. It is owned by the MPEG-LA consortium, which doesn’t charge royalties for its use today, but currently plans to start enforcing royalties in 2015. The royalty threat is the reason Mozilla supports an older open codex called Ogg Theora in Firefox instead of H.264.

But Google is donating a much better codec, called VP8, which it acquired with its purchase of On2 Techchnolgies. The WebM Project is a new container file format for Web video. It includes the VP8 video codec, the open Vorbis audio codec, file extensions and a new mime type. Any video player can adopt it, including Flash. And, in fact, Flash is one of the 40 launch technology partners supporting WebM.

Chrome, Firefox, and Opera browsers will all support WebM, and Google will give it a big push by making YouTube videos support it as well. Will Safari and IE join as well? Apple is pushing H.264 pretty hard, but there is no reason it couldn’t support WebM as well in the future. If it doesn’t, we might have a Web video standards war on our hands.

Other launch partners include Skype, Nvidia, Qualcomm, AMD, ARM, Brightcove, Encoding.com, Kaltura, and HD Cloud.