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"
28 void ff_celp_convolve_circ(
31 const int16_t* filter,
36 memset(fc_out, 0, len * sizeof(int16_t));
38 /* Since there are few pulses over an entire subframe (i.e. almost
39 all fc_in[i] are zero) it is faster to loop over fc_in first. */
45 fc_out[k] += (fc_in[i] * filter[len + k - i]) >> 15;
48 fc_out[k] += (fc_in[i] * filter[ k - i]) >> 15;
53 int ff_celp_lp_synthesis_filter(
55 const int16_t* filter_coeffs,
64 // Avoids a +1 in the inner loop.
67 for(n=0; n<buffer_length; n++)
70 for(i=1; i<filter_length; i++)
71 sum -= filter_coeffs[i-1] * out[n-i];
73 sum = (sum >> 12) + in[n];
75 if(sum + 0x8000 > 0xFFFFU)
79 sum = (sum >> 31) ^ 32767;
87 void ff_celp_lp_synthesis_filterf(
89 const float* filter_coeffs,
96 // Avoids a +1 in the inner loop.
99 for(n=0; n<buffer_length; n++)
102 for(i=1; i<filter_length; i++)
103 out[n] -= filter_coeffs[i-1] * out[n-i];
107 void ff_celp_lp_zero_synthesis_filterf(
109 const float* filter_coeffs,
116 // Avoids a +1 in the inner loop.
119 for(n=0; n<buffer_length; n++)
122 for(i=1; i<filter_length; i++)
123 out[n] -= filter_coeffs[i-1] * in[n-i];