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https://github.com/FFmpeg/FFmpeg.git
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b1ade3d182
"for (i = 1; i < num + 1; i++)" look like "for (i = 1; i <= num; i++)". Programmers worldwide rejoiced and used the operand, e.g. in the thread "[PATCH] remove ugliness in cel_filters.c", and He saw that it was good. Originally committed as revision 20489 to svn://svn.ffmpeg.org/ffmpeg/trunk
117 lines
3.5 KiB
C
117 lines
3.5 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(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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if (fc_in[i]) {
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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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void ff_celp_circ_addf(float *out, const float *in,
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const float *lagged, int lag, float fac, int n)
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{
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int k;
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for (k = 0; k < lag; k++)
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out[k] = in[k] + fac * lagged[n + k - lag];
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for (; k < n; k++)
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out[k] = in[k] + fac * lagged[ k - lag];
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}
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int ff_celp_lp_synthesis_filter(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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for (n = 0; n < buffer_length; n++) {
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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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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(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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for (n = 0; n < buffer_length; n++) {
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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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void ff_celp_lp_zero_synthesis_filterf(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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for (n = 0; n < buffer_length; n++) {
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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] * in[n-i];
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}
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}
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