830911f6f9
git-svn-id: svn://localhost/ardour2/branches/3.0@6760 d708f5d6-7413-0410-9779-e7cbd77b26cf
93 lines
3.3 KiB
C
93 lines
3.3 KiB
C
/*
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* Copyright (C) 2002 Steve Harris <steve@plugin.org.uk>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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*/
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#ifndef GDITHER_H
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#define GDITHER_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include "gdither_types.h"
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/* Create and initialise a state structure, takes a dither type, a number of
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* channels and a bit depth as input
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*
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* The Dither type is one of
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*
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* GDitherNone - straight nearest neighbour rounding. Theres no pressing
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* reason to do this at 8 or 16 bit, but you might want to at 24, for some
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* reason. At the lest it will save you writing int->float conversion code,
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* which is arder than it sounds.
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*
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* GDitherRect - mathematically most accurate, lowest noise floor, but not
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* that good for audio. It is the fastest though.
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*
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* GDitherTri - a happy medium between Rectangular and Shaped, reasonable
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* noise floor, not too obvious, quite fast.
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*
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* GDitherShaped - should have the least audible impact, but has the highest
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* noise floor, fairly CPU intensive. Not advisible if your going to apply
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* any frequency manipulation afterwards.
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*
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* channels, sets the number of channels in the output data, output data will
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* be written interleaved into the area given to gdither_run(). Set to 1
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* if you are not working with interleaved buffers.
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*
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* bit depth, sets the bit width of the output sample data, it can be one of:
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*
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* GDither8bit - 8 bit unsiged
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* GDither16bit - 16 bit signed
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* GDither32bit - 24+bits in upper bits of a 32 bit word
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* GDitherFloat - IEEE floating point (32bits)
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* GDitherDouble - Double precision IEEE floating point (64bits)
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*
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* dither_depth, set the number of bits before the signal will be truncated to,
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* eg. 16 will produce an output stream with 16bits-worth of signal. Setting to
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* zero or greater than the width of the output format will dither to the
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* maximum precision allowed by the output format.
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*/
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GDither gdither_new(GDitherType type, uint32_t channels,
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GDitherSize bit_depth, int dither_depth);
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/* Frees memory used by gdither_new.
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*/
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void gdither_free(GDither s);
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/* Applies dithering to the supplied signal.
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*
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* channel is the channel number you are processing (0 - channles-1), length is
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* the length of the input, in samples, x is the input samples (float), y is
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* where the output samples will be written, it should have the approaprate
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* type for the chosen bit depth
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*/
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void gdither_runf(GDither s, uint32_t channel, uint32_t length,
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float const *x, void *y);
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/* see gdither_runf, vut input argument is double format */
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void gdither_run(GDither s, uint32_t channel, uint32_t length,
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double const *x, void *y);
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#ifdef __cplusplus
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}
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#endif
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#endif
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