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106 lines
2.6 KiB
C
106 lines
2.6 KiB
C
/*
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* various filters for ACELP-based codecs
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*
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* Copyright (c) 2008 Vladimir Voroshilov
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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 <inttypes.h>
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#include "avcodec.h"
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#include "celp_filters.h"
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void ff_celp_convolve_circ(
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int16_t* fc_out,
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const int16_t* fc_in,
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const int16_t* filter,
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int len)
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{
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int i, k;
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memset(fc_out, 0, len * sizeof(int16_t));
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/* Since there are few pulses over an entire subframe (i.e. almost
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all fc_in[i] are zero) it is faster to loop over fc_in first. */
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for(i=0; i<len; i++)
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{
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if(fc_in[i])
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{
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for(k=0; k<i; k++)
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fc_out[k] += (fc_in[i] * filter[len + k - i]) >> 15;
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for(k=i; k<len; k++)
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fc_out[k] += (fc_in[i] * filter[ k - i]) >> 15;
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}
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}
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}
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int ff_celp_lp_synthesis_filter(
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int16_t *out,
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const int16_t* filter_coeffs,
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const int16_t* in,
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int buffer_length,
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int filter_length,
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int stop_on_overflow,
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int rounder)
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{
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int i,n;
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// Avoids a +1 in the inner loop.
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filter_length++;
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for(n=0; n<buffer_length; n++)
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{
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int sum = rounder;
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for(i=1; i<filter_length; i++)
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sum -= filter_coeffs[i-1] * out[n-i];
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sum = (sum >> 12) + in[n];
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if(sum + 0x8000 > 0xFFFFU)
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{
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if(stop_on_overflow)
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return 1;
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sum = (sum >> 31) ^ 32767;
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}
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out[n] = sum;
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}
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return 0;
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}
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void ff_celp_lp_synthesis_filterf(
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float *out,
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const float* filter_coeffs,
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const float* in,
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int buffer_length,
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int filter_length)
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{
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int i,n;
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// Avoids a +1 in the inner loop.
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filter_length++;
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for(n=0; n<buffer_length; n++)
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{
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out[n] = in[n];
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for(i=1; i<filter_length; i++)
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out[n] -= filter_coeffs[i-1] * out[n-i];
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}
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}
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