EA Command And Conquer 3 Audio Codec
EA XAS is a variation on the Electronic Arts XA codec that uses four independent PCM deltas and is used for audio in the PC/Mac versions of Command & Conquer 3, Red Alert 3 and Command & Conquer 4 as well as the Playstation 3 version of Red Alert 3. The XBOX 360 versions of these games use the Microsoft XMA ADPCM codec.
Compressed audio data is arranged in 76-byte blocks that follow sequentially after the header. Each block corresponds to 128 audio samples. In files with stereo audio, the blocks alternate between left and right channels. For example, the first block is for the first channel, the next is for the second channel and so on.
Each block beings with a 16-byte header, and is followed by 15 x 4-byte compressed audio blobs.
Thanks to KMX at Derelict Studios for finding out the initial information on this format as it applies to C&C3.