RealNetworks will release the underlying software code for its open source media player today, in a move that should allow developers to create free versions of the player to run on Windows, Mac OS X and Linux operating systems.

The release of the code marks the first in a series of open source products that the company plans to offer under its initiative known as Helix. Within the next year it is expected to release an open source media server as well as freely available technology to encode audio and video files.

The Helix DNA Client, which is available on the website today, is an open-source version of the engine that powers the company's commercial RealOne Player. It can be built into devices as diverse as mobile phones, set-top boxes, home audio receiver and PCs so that users can stream and play back digital media.

Initially, the company will ship the code required to build players that can be compiled to run on desktop operating systems from Microsoft, Apple and the Linux community. With some tuning the code can be modified for other operating systems such as those from Symbian and PalmSource, which can run on a variety of mobile devices.

"We actually are going to allow people to build essentially their own version of the RealOne Player," said Dan Sheeran, vice president of media systems at RealNetworks. "You can grab this code and port it to your platform as quickly as you want," he said.

The company is betting on the open-source development model to establish its media formats and related technology as a de facto standard for streaming and playing back media on PCs and other devices. RealNetworks competes against Microsoft and Apple, which also make media players and server technology based on their respective file formats.

Along with the release of the Helix DNA Client source code, RealNetworks said that it will give developers free access to its prized compression and decompression technology, or codec, so that open source players built with the Helix code will be able to play back RealAudio and RealVideo files.

The company won't distribute the source code for its codecs, rather it will distribute compiled versions of the software for each operating system supported, Sheeran said.

"We were unclear before as to whether we were going to allow [free] use of the format," Sheeran said. "People will be pleasantly surprised at how liberal we're being," he said.

Some open source developers initially criticised the company for not offering free access to its codecs as part of the open source initiative, which was first announced in July. Without such access, developers would have been able to build a free media player but would have had to pay royalties in order to allow the playback of Real media files on their players.

"In the beginning there was a lot of protest about the licensing agreements they came out with," said Max Flisi, research analyst with IDC, noting that the alterations to the licensing structure will likely quell earlier concerns. "RealNetworks wants to make it as easy and cost-effective as possible for companies to use this," he said.

Without any modification, players built with the Helix DNA Client will support RealAudio and RealVideo, MP3, Mpeg-4, the standard low bit rate video codec H.263, and 3GPP (third generation partnership project), a file format used by the mobile phone industry.

One highlight to RealNetworks' original announcement was that it had developed a technology that would allow files encoded in the Windows Media formats to be delivered over the internet using the Helix media server and played back on the free client software. That technology will not be included in the current release. Real hopes that developers will begin projects among themselves in order to add such support.

RealNetworks will release the source code under two licenses. One is an open source license allowing individual developers and universities to freely build versions of the media player for non-commercial use. That license, published in its first version today, is being submitted for certification by the Open Source Initiative.

A second, commercial license will be available for organisations that develop players for commercial purposes. Under that scenario companies will receive free licensing for the first million units shipped annually and pay a few pence per unit beyond that.

"The intention there is to facilitate both non-commercial and commercial uses," Sheeran said. "If you want to ship millions of copies that's not going to be free."

Acer, Hitachi, STMicroelectronics, and Nokia each said that they will back the Helix effort by implementing the technology in various computing and consumer electronics devices they ship.

The open source effort has received an overwhelming response from developers and manufacturers since it was first announced, according to RealNetworks. Roughly 2,000 developers have registered to be members of the Helix community which includes access to the source code and development tips, according to the company.

Initial projects to be taken on by the Helix developer community include creating a player for the Palm operating system and plug-ins for the Mozilla and Opera web browsers, Sheeran said.

Brian Behlendorf, chief technology officer of CollabNet, which is hosting the online community that will develop products with Helix code at, said the effort should be a popular one. While a variety of open source and commercial media players for Linux already exist, there are really no comprehensive offerings that support the leading file formats, he said.

"I think there's probably hope that the Real client can be the unifying force for all of that," said Behlendorf. "In the same way that was meeting a need for an open-source desktop productivity software, this could be the same kind of thing to the multimedia community".