/** * @file windgen.h * @brief Templated wind noise generation * * $LicenseInfo:firstyear=2002&license=viewergpl$ * * Copyright (c) 2002-2009, Linden Research, Inc. * * Second Life Viewer Source Code * The source code in this file ("Source Code") is provided by Linden Lab * to you under the terms of the GNU General Public License, version 2.0 * ("GPL"), unless you have obtained a separate licensing agreement * ("Other License"), formally executed by you and Linden Lab. Terms of * the GPL can be found in doc/GPL-license.txt in this distribution, or * online at http://secondlifegrid.net/programs/open_source/licensing/gplv2 * * There are special exceptions to the terms and conditions of the GPL as * it is applied to this Source Code. View the full text of the exception * in the file doc/FLOSS-exception.txt in this software distribution, or * online at * http://secondlifegrid.net/programs/open_source/licensing/flossexception * * By copying, modifying or distributing this software, you acknowledge * that you have read and understood your obligations described above, * and agree to abide by those obligations. * * ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO * WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY, * COMPLETENESS OR PERFORMANCE. * $/LicenseInfo$ */ #ifndef WINDGEN_H #define WINDGEN_H #include "llcommon.h" #include "llrand.h" template <class MIXBUFFERFORMAT_T> class LLWindGen { public: LLWindGen() : mTargetGain(0.f), mTargetFreq(100.f), mTargetPanGainR(0.5f), mbuf0(0.0), mbuf1(0.0), mbuf2(0.0), mbuf3(0.0), mbuf4(0.0), mbuf5(0.0), mY0(0.0), mY1(0.0), mCurrentGain(0.f), mCurrentFreq(100.f), mCurrentPanGainR(0.5f) {}; static const U32 getInputSamplingRate() {return mInputSamplingRate;} // newbuffer = the buffer passed from the previous DSP unit. // numsamples = length in samples-per-channel at this mix time. // stride = number of bytes between start of each sample. // NOTE: generates L/R interleaved stereo MIXBUFFERFORMAT_T* windGenerate(MIXBUFFERFORMAT_T *newbuffer, int numsamples, int stride) { U8 *cursamplep = (U8*)newbuffer; double bandwidth = 50.0F; double a0,b1,b2; // calculate resonant filter coeffs b2 = exp(-(F_TWO_PI) * (bandwidth / mInputSamplingRate)); while (numsamples--) { mCurrentFreq = (float)((0.999 * mCurrentFreq) + (0.001 * mTargetFreq)); mCurrentGain = (float)((0.999 * mCurrentGain) + (0.001 * mTargetGain)); mCurrentPanGainR = (float)((0.999 * mCurrentPanGainR) + (0.001 * mTargetPanGainR)); b1 = (-4.0 * b2) / (1.0 + b2) * cos(F_TWO_PI * (mCurrentFreq / mInputSamplingRate)); a0 = (1.0 - b2) * sqrt(1.0 - (b1 * b1) / (4.0 * b2)); double nextSample; // start with white noise nextSample = ll_frand(2.0f) - 1.0f; // apply pinking filter mbuf0 = 0.997f * mbuf0 + 0.0126502f * nextSample; mbuf1 = 0.985f * mbuf1 + 0.0139083f * nextSample; mbuf2 = 0.950f * mbuf2 + 0.0205439f * nextSample; mbuf3 = 0.850f * mbuf3 + 0.0387225f * nextSample; mbuf4 = 0.620f * mbuf4 + 0.0465932f * nextSample; mbuf5 = 0.250f * mbuf5 + 0.1093477f * nextSample; nextSample = mbuf0 + mbuf1 + mbuf2 + mbuf3 + mbuf4 + mbuf5; // do a resonant filter on the noise nextSample = (double)( a0 * nextSample - b1 * mY0 - b2 * mY1 ); mY1 = mY0; mY0 = nextSample; nextSample *= mCurrentGain; MIXBUFFERFORMAT_T sample; sample = llfloor(((F32)nextSample*32768.f*(1.0f - mCurrentPanGainR))+0.5f); *(MIXBUFFERFORMAT_T*)cursamplep = llclamp(sample, (MIXBUFFERFORMAT_T)-32768, (MIXBUFFERFORMAT_T)32767); cursamplep += stride; sample = llfloor(((F32)nextSample*32768.f*mCurrentPanGainR)+0.5f); *(MIXBUFFERFORMAT_T*)cursamplep = llclamp(sample, (MIXBUFFERFORMAT_T)-32768, (MIXBUFFERFORMAT_T)32767); cursamplep += stride; } return newbuffer; } F32 mTargetGain; F32 mTargetFreq; F32 mTargetPanGainR; private: static const U32 mInputSamplingRate = 44100; F64 mbuf0; F64 mbuf1; F64 mbuf2; F64 mbuf3; F64 mbuf4; F64 mbuf5; F64 mY0; F64 mY1; F32 mCurrentGain; F32 mCurrentFreq; F32 mCurrentPanGainR; }; #endif