RAX (RealAudio 10): The latest version of the RealAudio format, used for both streaming and downloading.
At low bit rates, RealAudio 10 uses the same high-compression codecs as previous versions of RealAudio, but above 128 kbps switches to AAC, allowing for better fidelity and compatibility with AAC-enabled players. The file extension for RealAudio 10 is .rax.