2 * various filters for ACELP-based codecs
4 * Copyright (c) 2008 Vladimir Voroshilov
6 * This file is part of FFmpeg.
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
26 #include "celp_filters.h"
27 #include "libavutil/avassert.h"
28 #include "libavutil/common.h"
30 void ff_celp_convolve_circ(int16_t* fc_out, const int16_t* fc_in,
31 const int16_t* filter, int len)
35 memset(fc_out, 0, len * sizeof(int16_t));
37 /* Since there are few pulses over an entire subframe (i.e. almost
38 all fc_in[i] are zero) it is faster to loop over fc_in first. */
39 for (i = 0; i < len; i++) {
41 for (k = 0; k < i; k++)
42 fc_out[k] += (fc_in[i] * filter[len + k - i]) >> 15;
44 for (k = i; k < len; k++)
45 fc_out[k] += (fc_in[i] * filter[ k - i]) >> 15;
50 void ff_celp_circ_addf(float *out, const float *in,
51 const float *lagged, int lag, float fac, int n)
54 for (k = 0; k < lag; k++)
55 out[k] = in[k] + fac * lagged[n + k - lag];
57 out[k] = in[k] + fac * lagged[ k - lag];
60 int ff_celp_lp_synthesis_filter(int16_t *out, const int16_t *filter_coeffs,
61 const int16_t *in, int buffer_length,
62 int filter_length, int stop_on_overflow,
63 int shift, int rounder)
67 for (n = 0; n < buffer_length; n++) {
68 int sum = rounder, sum1;
69 for (i = 1; i <= filter_length; i++)
70 sum -= (unsigned)(filter_coeffs[i-1] * out[n-i]);
72 sum1 = ((sum >> 12) + in[n]) >> shift;
73 sum = av_clip_int16(sum1);
75 if (stop_on_overflow && sum != sum1)
84 void ff_celp_lp_synthesis_filterf(float *out, const float *filter_coeffs,
85 const float* in, int buffer_length,
90 #if 0 // Unoptimized code path for improved readability
91 for (n = 0; n < buffer_length; n++) {
93 for (i = 1; i <= filter_length; i++)
94 out[n] -= filter_coeffs[i-1] * out[n-i];
97 float out0, out1, out2, out3;
98 float old_out0, old_out1, old_out2, old_out3;
101 a = filter_coeffs[0];
102 b = filter_coeffs[1];
103 c = filter_coeffs[2];
104 b -= filter_coeffs[0] * filter_coeffs[0];
105 c -= filter_coeffs[1] * filter_coeffs[0];
106 c -= filter_coeffs[0] * b;
108 av_assert2((filter_length&1)==0 && filter_length>=4);
114 for (n = 0; n <= buffer_length - 4; n+=4) {
115 float tmp0,tmp1,tmp2;
123 out0 -= filter_coeffs[2] * old_out1;
124 out1 -= filter_coeffs[2] * old_out2;
125 out2 -= filter_coeffs[2] * old_out3;
127 out0 -= filter_coeffs[1] * old_out2;
128 out1 -= filter_coeffs[1] * old_out3;
130 out0 -= filter_coeffs[0] * old_out3;
132 val = filter_coeffs[3];
134 out0 -= val * old_out0;
135 out1 -= val * old_out1;
136 out2 -= val * old_out2;
137 out3 -= val * old_out3;
139 for (i = 5; i < filter_length; i += 2) {
141 val = filter_coeffs[i-1];
143 out0 -= val * old_out3;
144 out1 -= val * old_out0;
145 out2 -= val * old_out1;
146 out3 -= val * old_out2;
148 old_out2 = out[-i-1];
150 val = filter_coeffs[i];
152 out0 -= val * old_out2;
153 out1 -= val * old_out3;
154 out2 -= val * old_out0;
155 out3 -= val * old_out1;
157 FFSWAP(float, old_out0, old_out2);
191 for (; n < buffer_length; n++) {
193 for (i = 1; i <= filter_length; i++)
194 out[n] -= filter_coeffs[i-1] * out[n-i];
199 void ff_celp_lp_zero_synthesis_filterf(float *out, const float *filter_coeffs,
200 const float *in, int buffer_length,
205 for (n = 0; n < buffer_length; n++) {
207 for (i = 1; i <= filter_length; i++)
208 out[n] += filter_coeffs[i-1] * in[n-i];
212 void ff_celp_filter_init(CELPFContext *c)
214 c->celp_lp_synthesis_filterf = ff_celp_lp_synthesis_filterf;
215 c->celp_lp_zero_synthesis_filterf = ff_celp_lp_zero_synthesis_filterf;
218 ff_celp_filter_init_mips(c);