typedef struct _AXPBSRC { u16 ratioHi; // sampling ratio, integer u16 ratioLo; // sampling ratio, fraction u16 currentAddressFrac; // current fractional sample position u16 last_samples[4]; // last 4 input samples } AXPBSRC;
The SRC values specify the operating parameters for the DSP's "front-end" sample rate converter.
Two 16-bit values specify the input-to-output ratio of samples the DSP must generate. The valid range is 1/512 to 4.0000. The ratioHi variable must be programmed with the integer portion of the ratio. The ratioLo variable must be programmed with the fractional portion of the ratio (2^16 * fraction).
The currentAddressFrac and last_samples[] variables are reserved for use by the DSP and must not be modified by the user, except when setting a voice to run. In this case, the last_samples[] must be set to zero.
Assert the AX_SYNC_USER_SRCRATIO bit in the axvpb.sync member when ratio* is changed.
Assert the AX_SYNC_USER_SRC bit in the axvpb.sync member to synchronize the entire AXPBSRC structure.
axvpb.sync
AXSetVoiceSrc
AXSetVoiceSrcRatio
03/01/2006 Initial version.