Software rivals Microsoft and Adobe Systems each unveiled products designed to grab a stake in the other's share of the online video market, blurring the line between desktop and web browser applications.

On Sunday Adobe announced its Adobe Media Player for Windows and Mac desktops, a standalone desktop version of its popular Flash Player browser plug-in.

Microsoft followed on Monday with Silverlight, a web browser plug-in for playing media files and interactive web applications.

The introduction of the applications represents an attempt by both companies to vie for a stake in a sector dominated by the other.

Microsoft's Windows Media Video (WMV) format is widely used to download videos, while Adobe's Flash Player has been the most popular choice for streaming videos from web browsers and is the plug-in of choice for sites such as YouTube and MySpace.com.

Adobe Media Player and Silverlight are both designed to play a developing class of software called rich interactive applications, or RIAs, which merge the power of desktop applications with the interconnectedness of web applications.

Adobe Media Player will be able to play video in a variety of formats, including Flash, which accounts for over 90 per cent of the video content available for viewing on web browsers.

The company also said the player will incorporate digital rights management technology and will allow advertising to be embedded in the content that can be playable offline.

The media player is built on the recently published Apollo platform, software that allows developers to create desktop-style applications using HTML, Flash, Javascript and XML, scripts traditionally used for web applications.
It is expected to launch a beta test later this year, with a final version slated for the end of 2007.

Silverlight, previously called Windows Presentation Foundation Everywhere (WPF/E), will be released in a beta version at the MIX 2007 web-designer conference in Las Vegas at the end of April.

The new plug-in will allow users of both Windows and Macintosh operating systems to view video on Microsoft's Explorer, Mozilla's Firefox or Apple's Safari using the WMV format.

Microsoft also announced a number of partnerships with companies that plan to support Silverlight, including Major League Baseball and online video retailer Netflix.