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authorMcCabe Maxsted2010-11-02 21:32:04 -0700
committerMcCabe Maxsted2010-11-02 21:32:04 -0700
commitb5074f1a8e3306f1be9e93172d26c97ff088cea0 (patch)
treea53d5cc54a1f339b7637a9d7d8248eca42995af2 /linden/indra/llaudio/llwindgen.h
parentRevert "Fix Bug #671 (aka VWR-1603): Duckwalk is too fast" (diff)
parentUploaded the linux64 libraries created by Aleric to imprudenceviewer.org (diff)
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Merged webkit_plugins into weekly. Huzzah! The weekly branch now has browser/media plugin support
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1/**
2 * @file windgen.h
3 * @brief Templated wind noise generation
4 *
5 * $LicenseInfo:firstyear=2002&license=viewergpl$
6 *
7 * Copyright (c) 2002-2009, Linden Research, Inc.
8 *
9 * Second Life Viewer Source Code
10 * The source code in this file ("Source Code") is provided by Linden Lab
11 * to you under the terms of the GNU General Public License, version 2.0
12 * ("GPL"), unless you have obtained a separate licensing agreement
13 * ("Other License"), formally executed by you and Linden Lab. Terms of
14 * the GPL can be found in doc/GPL-license.txt in this distribution, or
15 * online at http://secondlifegrid.net/programs/open_source/licensing/gplv2
16 *
17 * There are special exceptions to the terms and conditions of the GPL as
18 * it is applied to this Source Code. View the full text of the exception
19 * in the file doc/FLOSS-exception.txt in this software distribution, or
20 * online at
21 * http://secondlifegrid.net/programs/open_source/licensing/flossexception
22 *
23 * By copying, modifying or distributing this software, you acknowledge
24 * that you have read and understood your obligations described above,
25 * and agree to abide by those obligations.
26 *
27 * ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO
28 * WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY,
29 * COMPLETENESS OR PERFORMANCE.
30 * $/LicenseInfo$
31 */
32#ifndef WINDGEN_H
33#define WINDGEN_H
34
35#include "llcommon.h"
36#include "llrand.h"
37
38template <class MIXBUFFERFORMAT_T>
39class LLWindGen
40{
41public:
42 LLWindGen() :
43 mTargetGain(0.f),
44 mTargetFreq(100.f),
45 mTargetPanGainR(0.5f),
46 mbuf0(0.0),
47 mbuf1(0.0),
48 mbuf2(0.0),
49 mbuf3(0.0),
50 mbuf4(0.0),
51 mbuf5(0.0),
52 mY0(0.0),
53 mY1(0.0),
54 mCurrentGain(0.f),
55 mCurrentFreq(100.f),
56 mCurrentPanGainR(0.5f) {};
57
58 static const U32 getInputSamplingRate() {return mInputSamplingRate;}
59
60 // newbuffer = the buffer passed from the previous DSP unit.
61 // numsamples = length in samples-per-channel at this mix time.
62 // stride = number of bytes between start of each sample.
63 // NOTE: generates L/R interleaved stereo
64 MIXBUFFERFORMAT_T* windGenerate(MIXBUFFERFORMAT_T *newbuffer, int numsamples, int stride)
65 {
66 U8 *cursamplep = (U8*)newbuffer;
67
68 double bandwidth = 50.0F;
69 double a0,b1,b2;
70
71 // calculate resonant filter coeffs
72 b2 = exp(-(F_TWO_PI) * (bandwidth / mInputSamplingRate));
73
74 while (numsamples--)
75 {
76 mCurrentFreq = (float)((0.999 * mCurrentFreq) + (0.001 * mTargetFreq));
77 mCurrentGain = (float)((0.999 * mCurrentGain) + (0.001 * mTargetGain));
78 mCurrentPanGainR = (float)((0.999 * mCurrentPanGainR) + (0.001 * mTargetPanGainR));
79 b1 = (-4.0 * b2) / (1.0 + b2) * cos(F_TWO_PI * (mCurrentFreq / mInputSamplingRate));
80 a0 = (1.0 - b2) * sqrt(1.0 - (b1 * b1) / (4.0 * b2));
81 double nextSample;
82
83 // start with white noise
84 nextSample = ll_frand(2.0f) - 1.0f;
85
86 // apply pinking filter
87 mbuf0 = 0.997f * mbuf0 + 0.0126502f * nextSample;
88 mbuf1 = 0.985f * mbuf1 + 0.0139083f * nextSample;
89 mbuf2 = 0.950f * mbuf2 + 0.0205439f * nextSample;
90 mbuf3 = 0.850f * mbuf3 + 0.0387225f * nextSample;
91 mbuf4 = 0.620f * mbuf4 + 0.0465932f * nextSample;
92 mbuf5 = 0.250f * mbuf5 + 0.1093477f * nextSample;
93
94 nextSample = mbuf0 + mbuf1 + mbuf2 + mbuf3 + mbuf4 + mbuf5;
95
96 // do a resonant filter on the noise
97 nextSample = (double)( a0 * nextSample - b1 * mY0 - b2 * mY1 );
98 mY1 = mY0;
99 mY0 = nextSample;
100
101 nextSample *= mCurrentGain;
102
103 MIXBUFFERFORMAT_T sample;
104
105 sample = llfloor(((F32)nextSample*32768.f*(1.0f - mCurrentPanGainR))+0.5f);
106 *(MIXBUFFERFORMAT_T*)cursamplep = llclamp(sample, (MIXBUFFERFORMAT_T)-32768, (MIXBUFFERFORMAT_T)32767);
107 cursamplep += stride;
108
109 sample = llfloor(((F32)nextSample*32768.f*mCurrentPanGainR)+0.5f);
110 *(MIXBUFFERFORMAT_T*)cursamplep = llclamp(sample, (MIXBUFFERFORMAT_T)-32768, (MIXBUFFERFORMAT_T)32767);
111 cursamplep += stride;
112 }
113
114 return newbuffer;
115 }
116
117 F32 mTargetGain;
118 F32 mTargetFreq;
119 F32 mTargetPanGainR;
120
121private:
122 static const U32 mInputSamplingRate = 44100;
123 F64 mbuf0;
124 F64 mbuf1;
125 F64 mbuf2;
126 F64 mbuf3;
127 F64 mbuf4;
128 F64 mbuf5;
129 F64 mY0;
130 F64 mY1;
131 F32 mCurrentGain;
132 F32 mCurrentFreq;
133 F32 mCurrentPanGainR;
134};
135
136#endif