The head of Adobe Systems has questioned Microsoft's commitment to keeping its new Silverlight platform compatible with other operating systems besides Windows.

Silverlight, which is seen as Microsoft's challenger to Adobe's Flash format, was unveiled Monday at the National Association of Broadcasters trade show in Las Vegas.

"Microsoft, historically, has never demonstrated a commitment to maintaining a cross platform solution," Bruce Chizen, CEO of Adobe, said in an interview Tuesday in Tokyo. He cited Windows Media Player and Internet Explorer as examples of Microsoft products that are still being developed for Windows but have been ended for the Mac platform.

Chizen was happy to suggest that Silverlight may suffer the same fate.

"Even though they say Silverlight is going to be cross-platform, and maybe the first [version] will be, I'm not sure our customers or the people that are trying to deliver that content will have the degree of confidence that if they go with Microsoft, they'll be able to provide them with a complete cross-platform solution forever," he said.

Flash has been around for 10 years and for much of its life was best known as a platform for quirky animations, but its use has exploded recently along with the popularity of Web-based video sites like YouTube, which use Flash to deliver streaming video to users. It is quickly becoming the de facto standard for delivering streaming media over the Web, and with Silverlight Microsoft hopes to grab a slice of this lucrative market.

Adobe doesn't break out revenue for Flash alone, but it said last month that growth of Flash server products in its most recent quarter was more than enough to offset a decline in sales of its core applications, which dipped ahead of the anticipated release of new versions. It also credited the use of Flash in mobile phones as the main cause of a 59 percent jump in revenue at its mobile division during the same period.

With Flash fast expanding as a video delivery mechanism, Adobe used the same Las Vegas trade show to disclose its plans to extend Flash Video from the Web to the desktop with a standalone client, in effect taking on Microsoft's Windows Media Player and other software like Quicktime and Real Player.

"We were missing a couple of things," Chizen said, explaining the rationale for the application. "There are many people distributing video that would like to protect their video, in effect have DRM, and we enable DRM capability with the Adobe Media Player. Additionally, people are looking to monetize their video through clever advertising mechanisms and we're able to do that with the Adobe Media Player."

The software, which is due out later this year, also builds on the popularity of social networking by allowing users to rank or comment on videos directly from the software's interface.

Despite his apparent confidence that Adobe's offerings trump those from Microsoft, Chizen is careful not to underestimate the world's biggest software company.

"Microsoft is a US$50 billion monopolist who's in the software business. I take them very seriously," he said.

This year Adobe is also planning to launch Apollo, a technology that allows rich Internet applications to run offline. Chizen said he's excited about Apollo but disappointed that it hasn't been released yet.

In March, Adobe began offering an alpha version of the software, which has been downloaded 110,000 times, he said. The full version of the platform is due in the second half of this year.