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14<h1 align="left">axvpb.pb.rmtIIR</h1>
15
16<h2>C Specification</h2>
17
18<BLOCKQUOTE>
19<pre><CODE>
20typedef union __AXPBRMTIIR
21{
22    AXPBLPF    lpf;
23    AXPBBIQUAD biquad;
24
25} AXPBRMTIIR;
26</CODE></pre>
27</BLOCKQUOTE>
28
29<h2>Description</h2>
30
31<p>By setting <code>rmtIIR</code> appropriately, you can apply an IIR filter to the audio output from the Controller speaker.</p>
32
33<p>The 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>
34
35<p>As the IIR filter for the Controller speaker, choose either LPF or Biquad filters. Both types of filters are used in basically the same way as the filters for the main speaker  (i.e., <code>axvpb.pb.lpf</code> and <code>axvpb.pb.biquad</code>).</p>
36
37<p>The difference is that the two types of filters cannot be used at the same time.</p>
38
39<p>The method to reflect the filter parameters in the DSP is also different. When LPF filters have been selected, in order for changes to the filter coefficients <code>a0</code> and <code>b0</code> to be reflected in the DSP, you must assert the <CODE>AX_SYNC_USER_RMTIIR_COEF1</CODE> bit in the <CODE>axvpb.sync</CODE> member. When Biquad filters have been selected, in order for changes to the filter coefficients <code>b0</code> to <code>a2</code> to be reflected in the DSP, you must assert the <CODE>AX_SYNC_USER_RMTIIR_COEF2</CODE> bit. When the filter switch <code>on</code> is changed, you must assert the <code>AX_SYNC_USER_RMTIIR</code> bit so that the entire AXPBIIR union is reflected in the DSP.</p>
40
41
42<p>The IIR filter for the Controller speaker is independent for each voice, so you can select whether to turn the filter on/off, which filter type to use, and the cut-off frequency for each voice audio data. Note also 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 speaker and the Controller speaker at the same time.</p>
43
44<p><strong>Note: In order to correctly specify the filter type (LPF or Biquad) for the  IIR filter for the Controller speaker, you must set the appropriate value to the <code>on</code> member of the structure for each type. To use LPF filters, specify <code>AX_PB_LPF_ON(1)</code>.  To use Biquad filters, specify <code>AX_PB_BIQUAD_ON(2)</code>.  If you are using neither type of filter, specify <code>AX_PB_LPF_OFF/AX_PB_BIQUAD_OFF(both 0)</code>.</strong></p>
45
46
47<h2>See Also</h2>
48
49<p>
50<font face="Courier New"><a href="../Parameter_Blocks/AXPBLPF_lpf.html">axvpb.pb.lpf</a><br> <a href="../Parameter_Blocks/AXPBBIQUAD_biquad.html">axvpb.pb.biquad</a><br> <a href="../Voice_Parameter_Blocks/sync.html">axvpb.sync</a><br> <a href="../Voice_Parameters/AXSetVoiceRmtIIR.html">AXSetVoiceRmtIIR</a><br> <a href="../Voice_Parameters/AXSetVoiceRmtIIRCoefs.html">AXSetVoiceRmtIIRCoefs</a></font>
51</p>
52
53<h2>Revision History</h2>
54
55<P>
562006/11/14 Initial version.
57</P>
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