eas_pan.h revision a8c89077d78769bf4840fa91609edc51fe2fa02d 
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*/
63void EAS_CalcPanControl (EAS_INT pan, EAS_I16 *pGainLeft, EAS_I16 *pGainRight);
64
65#endif
66
67