YouTube have announced a beta of HTML5 support. These are broadcasting videos in H.264 format for browsers that understand HTML5's <video> tag. The choice of H.264 is perhaps unsurprising, since that's what Apple's iPhone supports natively (and indeed, is how the YouTube mobile application is rendered). This means that other browsers that don't support H.264 won't be able to render content.

The initial supported list includes Safari 4+, Google Chrome and the Chrome Frame plugin for Internet Explorer. Although FireFox 3.6 was released today with HTML5 support, it only supports the open-source OGG video format.

The HTML5 specification (which grew out of the WhatWG) includes a native tag for <video> and <audio> amongst other enhancements. However, there were disagreements about which codec to support for video rendering. (Codecs are programs that can decode a stream of binary data into a sequence of video frames.) At issue were questions of efficiency (which produces a smaller download, but also which is computationally easier to decode) and patents which protect those algorithms.

The choices lie between the patent-covered MPEG standard H.264, widely implemented in hardware and on mobile devices (such as the iPhone), and the open-source and probably unpatented Ogg format. Large companies (with the ability to execute licensing deals) such as Google and Apple are behind the H.264 format (having already licensed it for other uses), whereas open-source companies such as Firefox and Opera are backing the open-source Ogg format.

At one point, the WHATWG tried to standardise on a single video format, leading to a lengthy debate. In the end, in an effort to ensure that the WHATWG (now HTML5) group did not stagnate, Ian Hickson posted a compromise position of not demanding a single format. From the explanatory mail:

After an inordinate amount of discussions, both in public and privately, on the situation regarding codecs for <video> and <audio> in HTML5, I have reluctantly come to the conclusion that there is no suitable codec that all vendors are willing to implement and ship. The current [June 2009] situation is as follows: Apple refuses to implement Ogg Theora in Quicktime by default (as used by Safari), citing lack of hardware support and an uncertain patent landscape.

Google has implemented H.264 and Ogg Theora in Chrome, but cannot provide the H.264 codec license to third-party distributors of Chromium, and have indicated a belief that Ogg Theora's quality-per-bit is not yet suitable for the volume handled by YouTube.

Opera refuses to implement H.264, citing the obscene cost of the relevant patent licenses.

Mozilla refuses to implement H.264, as they would not be able to obtain a license that covers their downstream distributors.

ArsTechnica explored the issues in depth and the situation has not changed since. However, the HTML5 adoption of YouTube might be a popular swing in the balance.