diff options
author | Miller Puckette <millerpuckette@users.sourceforge.net> | 2007-08-18 23:52:12 +0000 |
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committer | Miller Puckette <millerpuckette@users.sourceforge.net> | 2007-08-18 23:52:12 +0000 |
commit | 49ad96d5effdf88cedb0e72bd7f534dc8e8158f7 (patch) | |
tree | 322b938a3aa1936207731682e1a1deb1161ef73f /pd/portaudio/src/common/pa_dither.h | |
parent | 494dc8e9c2ded66121b8d8bf311b58310cd2ba8c (diff) |
another try
svn path=/trunk/; revision=8659
Diffstat (limited to 'pd/portaudio/src/common/pa_dither.h')
-rw-r--r-- | pd/portaudio/src/common/pa_dither.h | 100 |
1 files changed, 100 insertions, 0 deletions
diff --git a/pd/portaudio/src/common/pa_dither.h b/pd/portaudio/src/common/pa_dither.h new file mode 100644 index 00000000..3f2d9101 --- /dev/null +++ b/pd/portaudio/src/common/pa_dither.h @@ -0,0 +1,100 @@ +#ifndef PA_DITHER_H +#define PA_DITHER_H +/* + * $Id: pa_dither.h,v 1.1 2007-08-18 23:52:12 millerpuckette Exp $ + * Portable Audio I/O Library triangular dither generator + * + * Based on the Open Source API proposed by Ross Bencina + * Copyright (c) 1999-2002 Phil Burk, Ross Bencina + * + * Permission is hereby granted, free of charge, to any person obtaining + * a copy of this software and associated documentation files + * (the "Software"), to deal in the Software without restriction, + * including without limitation the rights to use, copy, modify, merge, + * publish, distribute, sublicense, and/or sell copies of the Software, + * and to permit persons to whom the Software is furnished to do so, + * subject to the following conditions: + * + * The above copyright notice and this permission notice shall be + * included in all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, + * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. + * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR + * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF + * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION + * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. + */ + +/* + * The text above constitutes the entire PortAudio license; however, + * the PortAudio community also makes the following non-binding requests: + * + * Any person wishing to distribute modifications to the Software is + * requested to send the modifications to the original developer so that + * they can be incorporated into the canonical version. It is also + * requested that these non-binding requests be included along with the + * license above. + */ + +/** @file + @ingroup common_src + + @brief Functions for generating dither noise +*/ + + +#ifdef __cplusplus +extern "C" +{ +#endif /* __cplusplus */ + + +/** @brief State needed to generate a dither signal */ +typedef struct PaUtilTriangularDitherGenerator{ + unsigned long previous; + unsigned long randSeed1; + unsigned long randSeed2; +} PaUtilTriangularDitherGenerator; + + +/** @brief Initialize dither state */ +void PaUtil_InitializeTriangularDitherState( PaUtilTriangularDitherGenerator *ditherState ); + + +/** + @brief Calculate 2 LSB dither signal with a triangular distribution. + Ranged for adding to a 1 bit right-shifted 32 bit integer + prior to >>15. eg: +<pre> + signed long in = * + signed long dither = PaUtil_Generate16BitTriangularDither( ditherState ); + signed short out = (signed short)(((in>>1) + dither) >> 15); +</pre> + @return + A signed long with a range of +32767 to -32768 +*/ +signed long PaUtil_Generate16BitTriangularDither( PaUtilTriangularDitherGenerator *ditherState ); + + +/** + @brief Calculate 2 LSB dither signal with a triangular distribution. + Ranged for adding to a pre-scaled float. +<pre> + float in = * + float dither = PaUtil_GenerateFloatTriangularDither( ditherState ); + // use smaller scaler to prevent overflow when we add the dither + signed short out = (signed short)(in*(32766.0f) + dither ); +</pre> + @return + A float with a range of -2.0 to +1.99999. +*/ +float PaUtil_GenerateFloatTriangularDither( PaUtilTriangularDitherGenerator *ditherState ); + + + +#ifdef __cplusplus +} +#endif /* __cplusplus */ +#endif /* PA_DITHER_H */ |