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
];