Sorry, I mistook the forum.
If you're using XACT 3 from the DX SDK, then there is a "WMA" option for compression format when setting up your compression preset. I presume that using this setting actually puts the data in xWMA format in the wave bank. Note that xWMA has to do with the container/framing, not the actual bit stream.
To play xWMA on XAudio2, use an XMAWAVEFORMAT structure instead of the WAVEFORMATEX when creating the voice. It's defined in xma2defs.h, but apparently not documented in the SDK docs. Below is an excerpt:
/***************************************************************************
* XMA format structures
***************************************************************************/
// The currently recommended way to express format information for XMA2 files
// is the XMAWAVEFORMATEX structure. This structure is fully compliant with
// the WAVEFORMATEX standard and contains all the information needed to parse
// and manage XMA2 files in a compact way.
#define WAVE_FORMAT_XMA2 0x166
typedef struct XMA2WAVEFORMATEX
{
WAVEFORMATEX wfx;
// Meaning of the WAVEFORMATEX fields here:
// wFormatTag; // Audio format type; always WAVE_FORMAT_XMA2
// nChannels; // Channel count of the decoded audio
// nSamplesPerSec; // Sample rate of the decoded audio
// nAvgBytesPerSec; // Used internally by the XMA encoder
// nBlockAlign; // Decoded sample size; channels * wBitsPerSample / 8
// wBitsPerSample; // Bits per decoded mono sample; always 16 for XMA
// cbSize; // Size in bytes of the rest of this structure (34)
WORD NumStreams; // Number of audio streams (1 or 2 channels each)
DWORD ChannelMask; // Spatial positions of the channels in this file,
// stored as SPEAKER_xxx values (see audiodefs.h)
DWORD SamplesEncoded; // Total number of PCM samples the file decodes to
DWORD BytesPerBlock; // XMA block size (but the last one may be shorter)
DWORD PlayBegin; // First valid sample in the decoded audio
DWORD PlayLength; // Length of the valid part of the decoded audio
DWORD LoopBegin; // Beginning of the loop region in decoded sample terms
DWORD LoopLength; // Length of the loop region in decoded sample terms
BYTE LoopCount; // Number of loops; 0 = no looping, 255 == infinite
BYTE EncoderVersion; // Version of XMA encoder that generated the file
WORD BlockCount; // XMA blocks in file (and entries in its seek table)
} XMA2WAVEFORMATEX, *PXMA2WAVEFORMATEX;
