typedef struct XMA2STREAMFORMAT {  
    BYTE Channels;  
    BYTE RESERVED;  
    WORD ChannelMask;  
} XMA2STREAMFORMAT  

typedef struct XMA2STREAMFORMAT
{
    BYTE Channels;           // Number of channels in the stream (1 or 2)
    BYTE RESERVED;           // Reserved for future use
    WORD ChannelMask;        // Spatial positions of the channels in the stream
} XMA2STREAMFORMAT;