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/*
* various filters for ACELP-based codecs
*
* Copyright (c) 2008 Vladimir Voroshilov
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <inttypes.h>
#include "avcodec.h"
#include "celp_filters.h"
void ff_celp_convolve_circ(
int16_t* fc_out,
const int16_t* fc_in,
const int16_t* filter,
int len)
{
int i, k;
memset(fc_out, 0, len * sizeof(int16_t));
/* Since there are few pulses over an entire subframe (i.e. almost
all fc_in[i] are zero) it is faster to loop over fc_in first. */
for(i=0; i<len; i++)
{
if(fc_in[i])
{
for(k=0; k<i; k++)
fc_out[k] += (fc_in[i] * filter[len + k - i]) >> 15;
for(k=i; k<len; k++)
fc_out[k] += (fc_in[i] * filter[ k - i]) >> 15;
}
}
}
int ff_celp_lp_synthesis_filter(
int16_t *out,
const int16_t* filter_coeffs,
const int16_t* in,
int buffer_length,
int filter_length,
int stop_on_overflow,
int rounder)
{
int i,n;
// These two lines are to avoid a -1 subtraction in the main loop
filter_length++;
filter_coeffs--;
for(n=0; n<buffer_length; n++)
{
int sum = rounder;
for(i=1; i<filter_length; i++)
sum -= filter_coeffs[i] * out[n-i];
sum = (sum >> 12) + in[n];
if(sum + 0x8000 > 0xFFFFU)
{
if(stop_on_overflow)
return 1;
sum = (sum >> 31) ^ 32767;
}
out[n] = sum;
}
return 0;
}
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