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35 lines
1.2 KiB
35 lines
1.2 KiB
/* |
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* Copyright (c) 2011 Justin Ruggles |
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* |
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* This file is part of FFmpeg. |
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* |
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* FFmpeg is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public |
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* License as published by the Free Software Foundation; either |
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* version 2.1 of the License, or (at your option) any later version. |
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* |
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* FFmpeg 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 GNU |
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* Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public |
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* License along with FFmpeg; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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*/ |
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#include "libavutil/common.h" |
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#include "libavutil/mathematics.h" |
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#include "adx.h" |
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void ff_adx_calculate_coeffs(int cutoff, int sample_rate, int bits, int *coeff) |
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{ |
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double a, b, c; |
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a = M_SQRT2 - cos(2.0 * M_PI * cutoff / sample_rate); |
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b = M_SQRT2 - 1.0; |
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c = (a - sqrt((a + b) * (a - b))) / b; |
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coeff[0] = lrintf(c * 2.0 * (1 << bits)); |
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coeff[1] = lrintf(-(c * c) * (1 << bits)); |
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}
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