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14<h1 align="left">axvpb.pb.rmtIIR</h1>
15
16<h2>Syntax</h2>
17<dl><dd><pre class="construction">
18typedef union __AXPBRMTIIR
19{
20    AXPBLPF    lpf;
21    AXPBBIQUAD biquad;
22
23} AXPBRMTIIR;
24</pre></dd></dl>
25
26<h2>Description</h2>
27<p>By setting <SPAN class="argument">rmtIIR</SPAN> appropriately, you can apply an IIR filter to the audio output from the Controller speaker.</p>
28
29<p>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.</p>
30
31<p>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, <code>axvpb.pb.lpf</code> and <code>axvpb.pb.biquad</code>).</p>
32
33<p>The difference is that the two types of filters cannot be used at the same time.</p>
34
35<p>The method for reflecting filter parameters in the DSP is also different. When LPF filters are selected, for changes to the <SPAN class="argument">a0</SPAN> and <SPAN class="argument">b0</SPAN> filter coefficients to be applied in DSP, assert the <CODE>AX_SYNC_USER_RMTIIR_COEF1</CODE> bit in the <CODE>axvpb.sync</CODE> member. When Biquad filters are selected, for changes to the <SPAN class="argument">b0</SPAN> and <SPAN class="argument">a2</SPAN> filter coefficients  to be reflected in DSP, assert the <CODE>AX_SYNC_USER_RMTIIR_COEF2</CODE> bit. When filter switches such as <SPAN class="argument">on</SPAN> are changed, assert the <code>AX_SYNC_USER_RMTIIR</code> bit such that the entire <CODE>AXPBIIR</CODE> union is reflected in DSP.</p>
36
37
38<p>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.</p>
39
40<p><strong>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 <SPAN class="argument">on</SPAN> member of the structure for each type. To use LPF filters, specify <code>AX_PB_LPF_ON(1)</code>; for Biquad filters, <code>AX_PB_BIQUAD_ON(2)</code>;  for neither type of filters, <code>AX_PB_LPF_OFF/AX_PB_BIQUAD_OFF(both 0)</code>.</strong></p>
41
42
43<h2>See Also</h2>
44<p class="reference">
45<a href="../Parameter_Blocks/AXPBLPF_lpf.html"><CODE>axvpb.pb.lpf</CODE></a>, <a href="../Parameter_Blocks/AXPBBIQUAD_biquad.html"><CODE>axvpb.pb.biquad</CODE></a>, <a href="../Voice_Parameter_Blocks/sync.html"><CODE>axvpb.sync</CODE></a>, <a href="../Voice_Parameters/AXSetVoiceRmtIIR.html"><CODE>AXSetVoiceRmtIIR</CODE></a>, <a href="../Voice_Parameters/AXSetVoiceRmtIIRCoefs.html"><CODE>AXSetVoiceRmtIIRCoefs</CODE></a>
46</p>
47
48<h2>Revision History</h2>
49<P>
502006/11/14 Initial version. <br>
51</P>
52
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