typedef union __AXPBRMTIIR
{
AXPBLPF lpf;
AXPBBIQUAD biquad;
} AXPBRMTIIR;
By setting rmtIIR appropriately, you can apply an IIR filter to the audio output from the Controller speaker.
IIR filter is applied on the AX voice process pipeline just before the audio data is converted from 32 kHz for the main speaker to 6 kHz for the Controller speaker.
As the IIR filter for the Controller speaker, choose either LPF or Biquad filters. Both types of filters are used in fundamentally the same way as the main speaker filters (that is, axvpb.pb.lpf and axvpb.pb.biquad).
The difference is that the two types of filters cannot be used at the same time.
The method for reflecting filter parameters in the DSP is also different. When LPF filters are selected, for changes to the a0 and b0 filter coefficients to be applied in DSP, assert the AX_SYNC_USER_RMTIIR_COEF1 bit in the axvpb.sync member. When Biquad filters are selected, for changes to the b0 and a2 filter coefficients to be reflected in DSP, assert the AX_SYNC_USER_RMTIIR_COEF2 bit. When filter switches such as on are changed, assert the AX_SYNC_USER_RMTIIR bit such that the entire AXPBIIR union is reflected in DSP.
Because the Controller speaker's IIR filter is independent for each voice, you can turn the filter on or off, and choose the type of filter and the cut-off frequency for each voice audio data. Note that because the IIR filter for the Controller speaker operates independently of the LPF and Biquad filters for the main speaker, you can use different cut-off frequencies for the main and Controller speakers at the same time.
Note: To correctly specify the filter type (LPF or Biquad) for the Controller speaker's IIR filter, you must set the appropriate value to the on member of the structure for each type. To use LPF filters, specify AX_PB_LPF_ON(1); for Biquad filters, AX_PB_BIQUAD_ON(2); for neither type of filters, AX_PB_LPF_OFF/AX_PB_BIQUAD_OFF(both 0).
axvpb.pb.lpf, axvpb.pb.biquad, axvpb.sync, AXSetVoiceRmtIIR, AXSetVoiceRmtIIRCoefs
2006/11/14 Initial version.
CONFIDENTIAL