163 lines
4.4 KiB
C
163 lines
4.4 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 "acelp_filters.h"
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const int16_t ff_acelp_interp_filter[61] =
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{ /* (0.15) */
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29443, 28346, 25207, 20449, 14701, 8693,
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3143, -1352, -4402, -5865, -5850, -4673,
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-2783, -672, 1211, 2536, 3130, 2991,
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2259, 1170, 0, -1001, -1652, -1868,
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-1666, -1147, -464, 218, 756, 1060,
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1099, 904, 550, 135, -245, -514,
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-634, -602, -451, -231, 0, 191,
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308, 340, 296, 198, 78, -36,
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-120, -163, -165, -132, -79, -19,
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34, 73, 91, 89, 70, 38,
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0,
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};
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void ff_acelp_interpolate(
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int16_t* out,
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const int16_t* in,
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const int16_t* filter_coeffs,
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int precision,
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int frac_pos,
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int filter_length,
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int length)
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{
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int n, i;
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assert(pitch_delay_frac >= 0 && pitch_delay_frac < precision);
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for(n=0; n<length; n++)
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{
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int idx = 0;
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int v = 0x4000;
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for(i=0; i<filter_length;)
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{
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/* The reference G.729 and AMR fixed point code performs clipping after
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each of the two following accumulations.
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Since clipping affects only the synthetic OVERFLOW test without
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causing an int type overflow, it was moved outside the loop. */
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/* R(x):=ac_v[-k+x]
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v += R(n-i)*ff_acelp_interp_filter(t+6i)
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v += R(n+i+1)*ff_acelp_interp_filter(6-t+6i) */
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v += in[n + i] * filter_coeffs[idx + frac_pos];
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idx += precision;
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i++;
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v += in[n - i] * filter_coeffs[idx - frac_pos];
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}
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out[n] = av_clip_int16(v >> 15);
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}
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}
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void ff_acelp_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_acelp_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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// These two lines are to avoid a -1 subtraction in the main loop
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filter_length++;
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filter_coeffs--;
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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] * 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_acelp_high_pass_filter(
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int16_t* out,
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int hpf_f[2],
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const int16_t* in,
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int length)
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{
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int i;
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int tmp;
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for(i=0; i<length; i++)
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{
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tmp = (hpf_f[0]* 15836LL)>>13; /* (14.13) = (13.13) * (1.13) */
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tmp += (hpf_f[1]* -7667LL)>>13; /* (13.13) = (13.13) * (0.13) */
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tmp += 7699 * (in[i] - 2*in[i-1] + in[i-2]); /* (14.13) = (0.13) * (14.0) */
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out[i] = av_clip_int16((tmp + 0x800) >> 12); /* (15.0) = 2 * (13.13) = (14.13) */
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hpf_f[1] = hpf_f[0];
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hpf_f[0] = tmp;
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}
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}
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