When RealNetworks redesigned Rhapsody for 3.0 they chose to restructure how the digital rights management architecture worked. Before 3.0 in Rhapsody, wma files were downloaded on-the-fly, except into an encrypted 500Mb cache file hidden within the Rhapsody program files folder. In version 3.0 they modified Rhapsody to support 2 DRM systems, where as before it was just an encrypted cache file.
One DRM system was Windows Media DRM and the other Helix DRM. For subscription downloading they utilized Windows Media DRM (WMA). For purchases they utilized Helix DRM (RAX AAC files). When they did this system, Rhapsody no longer required the secure cache file, as licenses and keys secured the files themselves. When they did this, and since Real wanted to support the entire digital audio player market, they invented Harmony Technology. All Harmony Technology does is convert between audio formats, while maintaining the DRM after conversion.
RAX (Advanced Audio Coding) to WMA conversion.
When they launched Rhapsody 4.0, the idea was to use both DRM’s and formats for the subscription services, while maintaining Rhapsody purchases as Helix DRM only (RAX AAC files). In Rhapsody there is no purchasing files in WMA, like there is in Napster and Yahoo Music Unlimited provide. You can select either Rhapsody DNA (Helix DRM) or PlayForSure (Windows Media DRM) for subscription content. If you purchase a Rhapsody song it is in the RAX AAC format and if your digital audio player does not support Rhapsody DNA/RAX natively, but it supports PlayForSure/WMA, then it will convert the RAX AAC files to Windows Media Audio with Windows Media DRM.
Only select Sandisk and iRiver devices supports Helix DRM (Rhapsody DNA) at the present. Everything else is Windows Media DRM. (Even the new Sony Walkmans.)
The Sandisk Rhapsody devices (e200 R series) are only exclusively sold @ BestBuy. (BestBuy’s Digital Music Store is regular Rhapsody with Best Buy branding.)
Helix DRM/Rhapsody DNA was a DRM scheme developed in-house by RealNetworks.
Apple developed FairPlay DRM for iTunes.
Sony developed OpenMG/MagicGate DRM for SonicStage/Sony CONNECT. (Abadoned everywhere in March 2008, except maybe Japan in Sony MORA.)
Microsoft developed Windows Media DRM for use in Rhapsody, Napster, Yahoo Music Unlimited, Wal-Mart Music Downloads, F.Y.E. Downloads and the late Virgin Digital.
RealNetworks developed Helix DRM for the Rhapsody Music Store and the RealMusic Store within RealPlayer 10/11.