Microsoft Corp. has purchased a 10 percent stake in Internet start-up Progressive Networks Inc. in an effort to gain more control over standards for delivering audio and video over the Internet.

Company officials declined to give financial details, but one analyst estimated Microsoft invested $30 million for a non-voting stake in the 3-year-old Seattle company known for its RealAudio and RealVideo ``streaming'' multimedia technology.

According to Microsoft they have agreed to the following:

* Microsoft will license RealAudio and RealVideo 4.0 technologies and trademarks for incorporation into its NetShow(TM) streaming server, which will become part of Microsoft Site Server, providing compatibility with the broadest array of existing content. Microsoft and Progressive Networks will ensure that clients and servers from either company will interoperate using RealAudio and RealVideo.

* The companies will work cooperatively and with other industry partners to define future versions of Microsoft's Active Streaming Format (ASF). Both companies will use ASF as the native streaming format for the next version of their streaming media product developments, in addition to supporting the existing Progressive Networks formats. Progressive Networks will use the Microsoft DirectShow and DirectDraw(R) APIs in the next versions of its Windows(R) operating systems-based clients, and plans aggressive support of Microsoft technologies. This will ensure that Web developers can use common file formats and client programming models.

* Microsoft will include both the RealPlayer 4.0 and NetShow clients with Microsoft Internet Explorer. Microsoft will distribute Progressive Networks' EasyStart RealAudio and RealVideo Server with NetShow 2.0 until Microsoft releases a product compatible with RealAudio and RealVideo.

* Microsoft is making an investment with non-voting minority interest in Progressive Networks.

"Microsoft believes streaming audio and video technology is and will continue to be a critical technology for providing rich information on the Internet and corporate intranets," said Paul Maritz, group vice president, platforms and applications at Microsoft. "Progressive Networks has strong technology that we will be licensing, and we look forward to working together."

Glaser said Progressive Networks was poised to play a key role in the television and radio of the future, which he predicted would be delivered over Internet-style networks.

``If you look at the digital convergence that everyone is talking about, we're thrilled with the start we've got, but that's tiny compared with where we're going,'' he said in a conference call with analysts and reporters.

Both companies will continue to enhance and market their streaming media products. Progressive Networks will continue to enhance and market its full line of products, including RealAudio and RealVideo, its professional product series and its enhanced RealPlayer 4.0 client.

Glaser, a former Microsoft vice president, said his company currently holds an 85 percent share of the market for streaming audio players, with some 20 million copies downloaded free over the Internet. The company also has sold 500,000 copies of an upgrade version at about $30 each, he said.