Line data Source code
1 : /***********************************************************************
2 : Copyright (c) 2006-2011, Skype Limited. All rights reserved.
3 : Redistribution and use in source and binary forms, with or without
4 : modification, are permitted provided that the following conditions
5 : are met:
6 : - Redistributions of source code must retain the above copyright notice,
7 : this list of conditions and the following disclaimer.
8 : - Redistributions in binary form must reproduce the above copyright
9 : notice, this list of conditions and the following disclaimer in the
10 : documentation and/or other materials provided with the distribution.
11 : - Neither the name of Internet Society, IETF or IETF Trust, nor the
12 : names of specific contributors, may be used to endorse or promote
13 : products derived from this software without specific prior written
14 : permission.
15 : THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
16 : AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 : IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 : ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
19 : LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
20 : CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
21 : SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
22 : INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
23 : CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
24 : ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
25 : POSSIBILITY OF SUCH DAMAGE.
26 : ***********************************************************************/
27 :
28 : #ifdef HAVE_CONFIG_H
29 : #include "config.h"
30 : #endif
31 :
32 : /*
33 : Elliptic/Cauer filters designed with 0.1 dB passband ripple,
34 : 80 dB minimum stopband attenuation, and
35 : [0.95 : 0.15 : 0.35] normalized cut off frequencies.
36 : */
37 :
38 : #include "main.h"
39 :
40 : /* Helper function, interpolates the filter taps */
41 0 : static OPUS_INLINE void silk_LP_interpolate_filter_taps(
42 : opus_int32 B_Q28[ TRANSITION_NB ],
43 : opus_int32 A_Q28[ TRANSITION_NA ],
44 : const opus_int ind,
45 : const opus_int32 fac_Q16
46 : )
47 : {
48 : opus_int nb, na;
49 :
50 0 : if( ind < TRANSITION_INT_NUM - 1 ) {
51 0 : if( fac_Q16 > 0 ) {
52 0 : if( fac_Q16 < 32768 ) { /* fac_Q16 is in range of a 16-bit int */
53 : /* Piece-wise linear interpolation of B and A */
54 0 : for( nb = 0; nb < TRANSITION_NB; nb++ ) {
55 0 : B_Q28[ nb ] = silk_SMLAWB(
56 : silk_Transition_LP_B_Q28[ ind ][ nb ],
57 : silk_Transition_LP_B_Q28[ ind + 1 ][ nb ] -
58 : silk_Transition_LP_B_Q28[ ind ][ nb ],
59 : fac_Q16 );
60 : }
61 0 : for( na = 0; na < TRANSITION_NA; na++ ) {
62 0 : A_Q28[ na ] = silk_SMLAWB(
63 : silk_Transition_LP_A_Q28[ ind ][ na ],
64 : silk_Transition_LP_A_Q28[ ind + 1 ][ na ] -
65 : silk_Transition_LP_A_Q28[ ind ][ na ],
66 : fac_Q16 );
67 : }
68 : } else { /* ( fac_Q16 - ( 1 << 16 ) ) is in range of a 16-bit int */
69 0 : silk_assert( fac_Q16 - ( 1 << 16 ) == silk_SAT16( fac_Q16 - ( 1 << 16 ) ) );
70 : /* Piece-wise linear interpolation of B and A */
71 0 : for( nb = 0; nb < TRANSITION_NB; nb++ ) {
72 0 : B_Q28[ nb ] = silk_SMLAWB(
73 : silk_Transition_LP_B_Q28[ ind + 1 ][ nb ],
74 : silk_Transition_LP_B_Q28[ ind + 1 ][ nb ] -
75 : silk_Transition_LP_B_Q28[ ind ][ nb ],
76 : fac_Q16 - ( (opus_int32)1 << 16 ) );
77 : }
78 0 : for( na = 0; na < TRANSITION_NA; na++ ) {
79 0 : A_Q28[ na ] = silk_SMLAWB(
80 : silk_Transition_LP_A_Q28[ ind + 1 ][ na ],
81 : silk_Transition_LP_A_Q28[ ind + 1 ][ na ] -
82 : silk_Transition_LP_A_Q28[ ind ][ na ],
83 : fac_Q16 - ( (opus_int32)1 << 16 ) );
84 : }
85 : }
86 : } else {
87 0 : silk_memcpy( B_Q28, silk_Transition_LP_B_Q28[ ind ], TRANSITION_NB * sizeof( opus_int32 ) );
88 0 : silk_memcpy( A_Q28, silk_Transition_LP_A_Q28[ ind ], TRANSITION_NA * sizeof( opus_int32 ) );
89 : }
90 : } else {
91 0 : silk_memcpy( B_Q28, silk_Transition_LP_B_Q28[ TRANSITION_INT_NUM - 1 ], TRANSITION_NB * sizeof( opus_int32 ) );
92 0 : silk_memcpy( A_Q28, silk_Transition_LP_A_Q28[ TRANSITION_INT_NUM - 1 ], TRANSITION_NA * sizeof( opus_int32 ) );
93 : }
94 0 : }
95 :
96 : /* Low-pass filter with variable cutoff frequency based on */
97 : /* piece-wise linear interpolation between elliptic filters */
98 : /* Start by setting psEncC->mode <> 0; */
99 : /* Deactivate by setting psEncC->mode = 0; */
100 0 : void silk_LP_variable_cutoff(
101 : silk_LP_state *psLP, /* I/O LP filter state */
102 : opus_int16 *frame, /* I/O Low-pass filtered output signal */
103 : const opus_int frame_length /* I Frame length */
104 : )
105 : {
106 0 : opus_int32 B_Q28[ TRANSITION_NB ], A_Q28[ TRANSITION_NA ], fac_Q16 = 0;
107 0 : opus_int ind = 0;
108 :
109 0 : silk_assert( psLP->transition_frame_no >= 0 && psLP->transition_frame_no <= TRANSITION_FRAMES );
110 :
111 : /* Run filter if needed */
112 0 : if( psLP->mode != 0 ) {
113 : /* Calculate index and interpolation factor for interpolation */
114 : #if( TRANSITION_INT_STEPS == 64 )
115 0 : fac_Q16 = silk_LSHIFT( TRANSITION_FRAMES - psLP->transition_frame_no, 16 - 6 );
116 : #else
117 : fac_Q16 = silk_DIV32_16( silk_LSHIFT( TRANSITION_FRAMES - psLP->transition_frame_no, 16 ), TRANSITION_FRAMES );
118 : #endif
119 0 : ind = silk_RSHIFT( fac_Q16, 16 );
120 0 : fac_Q16 -= silk_LSHIFT( ind, 16 );
121 :
122 0 : silk_assert( ind >= 0 );
123 0 : silk_assert( ind < TRANSITION_INT_NUM );
124 :
125 : /* Interpolate filter coefficients */
126 0 : silk_LP_interpolate_filter_taps( B_Q28, A_Q28, ind, fac_Q16 );
127 :
128 : /* Update transition frame number for next frame */
129 0 : psLP->transition_frame_no = silk_LIMIT( psLP->transition_frame_no + psLP->mode, 0, TRANSITION_FRAMES );
130 :
131 : /* ARMA low-pass filtering */
132 : silk_assert( TRANSITION_NB == 3 && TRANSITION_NA == 2 );
133 0 : silk_biquad_alt_stride1( frame, B_Q28, A_Q28, psLP->In_LP_State, frame, frame_length);
134 : }
135 0 : }
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