diff options
Diffstat (limited to 'indra/llaudio/llwindgen.h')
| -rw-r--r-- | indra/llaudio/llwindgen.h | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/indra/llaudio/llwindgen.h b/indra/llaudio/llwindgen.h new file mode 100644 index 0000000000..847bfa6e9d --- /dev/null +++ b/indra/llaudio/llwindgen.h @@ -0,0 +1,136 @@ +/** + * @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 |