1 /*----------------------------------------------------------------------------
2  *
3  * File:
4  * eas_pan.h
5  *
6  * Contents and purpose:
7  * Calculates left and right gain multipliers based on a pan value from -63 to +63
8  *
9  * NOTES:
10  * The _CMX_PARSER and _MFI_PARSER preprocessor symbols determine
11  * whether the parser works for those particular file formats.
12  *
13  * Copyright Sonic Network Inc. 2005
14 
15  * Licensed under the Apache License, Version 2.0 (the "License");
16  * you may not use this file except in compliance with the License.
17  * You may obtain a copy of the License at
18  *
19  *      http://www.apache.org/licenses/LICENSE-2.0
20  *
21  * Unless required by applicable law or agreed to in writing, software
22  * distributed under the License is distributed on an "AS IS" BASIS,
23  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
24  * See the License for the specific language governing permissions and
25  * limitations under the License.
26  *
27  *----------------------------------------------------------------------------
28  * Revision Control:
29  *   $Revision: 82 $
30  *   $Date: 2006-07-10 11:45:19 -0700 (Mon, 10 Jul 2006) $
31  *----------------------------------------------------------------------------
32 */
33 
34 #ifndef EAS_PAN_H
35 #define _EAS_PAN_H
36 
37 #include "eas_types.h"
38 
39 /*----------------------------------------------------------------------------
40  * EAS_CalcPanControl()
41  *----------------------------------------------------------------------------
42  * Purpose:
43  * Assign the left and right gain values corresponding to the given pan value.
44  *
45  * This routine uses sin/cos approximations for an equal power curve:
46  *
47  * sin(x) = (2-4*c)*x^2 + c + x
48  * cos(x) = (2-4*c)*x^2 + c - x
49  *
50  * where  c = 1/sqrt(2)
51  * using the a0 + x*(a1 + x*a2) approach
52  *
53  * Inputs:
54  * pan          - pan value (-63 to + 63)
55  *
56  * Outputs:
57  * pGainLeft    linear gain multiplier for left channel (15-bit fraction)
58  * pGainRight   linear gain multiplier for left channel (15-bit fraction)
59  *
60  * Side Effects:
61  *----------------------------------------------------------------------------
62 */
63 void EAS_CalcPanControl (EAS_INT pan, EAS_I16 *pGainLeft, EAS_I16 *pGainRight);
64 
65 #endif
66 
67