b237248e29
Instead of using fixed coefficients, the correct way is to calculate the coefficients using the highpass cutoff frequency from the ADX stream header and the sample rate.
61 lines
1.7 KiB
C
61 lines
1.7 KiB
C
/*
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* ADX ADPCM codecs
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* Copyright (c) 2001,2003 BERO
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*
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* This file is part of Libav.
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*
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* Libav 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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* Libav 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 Libav; 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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/**
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* @file
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* SEGA CRI adx codecs.
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*
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* Reference documents:
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* http://ku-www.ss.titech.ac.jp/~yatsushi/adx.html
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* adx2wav & wav2adx http://www.geocities.co.jp/Playtown/2004/
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*/
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#ifndef AVCODEC_ADX_H
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#define AVCODEC_ADX_H
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typedef struct {
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int s1,s2;
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} ADXChannelState;
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typedef struct {
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int channels;
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ADXChannelState prev[2];
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int header_parsed;
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unsigned char dec_temp[18*2];
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int in_temp;
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int cutoff;
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int coeff[2];
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} ADXContext;
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#define COEFF_BITS 12
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/**
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* Calculate LPC coefficients based on cutoff frequency and sample rate.
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*
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* @param cutoff cutoff frequency
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* @param sample_rate sample rate
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* @param bits number of bits used to quantize coefficients
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* @param[out] coeff 2 quantized LPC coefficients
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*/
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void ff_adx_calculate_coeffs(int cutoff, int sample_rate, int bits, int *coeff);
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#endif /* AVCODEC_ADX_H */
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