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https://github.com/claunia/flac.git
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29a28338c3
Adds two new apodization functions that seem to perform better than the apodization functions currently in the codebase and fixes three existing windows as well. Its important to note that this patch only affects the encoder stage that evaluates various possible predictors. Audio encoded with these new windows will still decode with existing legacy decoders. = Theory = These functions are used to window the audio data at the predictor stage. These news functions enable the use of only part of the signal to generate a predictor. This helps because short transients can introduce noise into the predictor. The predictor becomes very good at prediciting one part of the signal, instead of mediocre for the whole block. Signed-off-by: Erik de Castro Lopo <erikd@mega-nerd.com>
75 lines
3.5 KiB
C
75 lines
3.5 KiB
C
/* libFLAC - Free Lossless Audio Codec library
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* Copyright (C) 2006-2009 Josh Coalson
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* Copyright (C) 2011-2013 Xiph.Org Foundation
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* - Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* - Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* - Neither the name of the Xiph.org Foundation nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef FLAC__PRIVATE__WINDOW_H
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#define FLAC__PRIVATE__WINDOW_H
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#include "private/float.h"
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#include "FLAC/format.h"
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#ifndef FLAC__INTEGER_ONLY_LIBRARY
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/*
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* FLAC__window_*()
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* --------------------------------------------------------------------
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* Calculates window coefficients according to different apodization
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* functions.
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*
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* OUT window[0,L-1]
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* IN L (number of points in window)
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*/
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void FLAC__window_bartlett(FLAC__real *window, const FLAC__int32 L);
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void FLAC__window_bartlett_hann(FLAC__real *window, const FLAC__int32 L);
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void FLAC__window_blackman(FLAC__real *window, const FLAC__int32 L);
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void FLAC__window_blackman_harris_4term_92db_sidelobe(FLAC__real *window, const FLAC__int32 L);
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void FLAC__window_connes(FLAC__real *window, const FLAC__int32 L);
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void FLAC__window_flattop(FLAC__real *window, const FLAC__int32 L);
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void FLAC__window_gauss(FLAC__real *window, const FLAC__int32 L, const FLAC__real stddev); /* 0.0 < stddev <= 0.5 */
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void FLAC__window_hamming(FLAC__real *window, const FLAC__int32 L);
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void FLAC__window_hann(FLAC__real *window, const FLAC__int32 L);
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void FLAC__window_kaiser_bessel(FLAC__real *window, const FLAC__int32 L);
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void FLAC__window_nuttall(FLAC__real *window, const FLAC__int32 L);
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void FLAC__window_rectangle(FLAC__real *window, const FLAC__int32 L);
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void FLAC__window_triangle(FLAC__real *window, const FLAC__int32 L);
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void FLAC__window_tukey(FLAC__real *window, const FLAC__int32 L, const FLAC__real p);
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void FLAC__window_partial_tukey(FLAC__real *window, const FLAC__int32 L, const FLAC__real p, const FLAC__real start, const FLAC__real end);
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void FLAC__window_punchout_tukey(FLAC__real *window, const FLAC__int32 L, const FLAC__real p, const FLAC__real start, const FLAC__real end);
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void FLAC__window_welch(FLAC__real *window, const FLAC__int32 L);
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#endif /* !defined FLAC__INTEGER_ONLY_LIBRARY */
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#endif
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