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annotate src/opus-1.3/silk/LP_variable_cutoff.c @ 83:ae30d91d2ffe

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Replace these with versions built using an older toolset (so as to avoid ABI compatibilities when linking on Ubuntu 14.04 for packaging purposes)
author Chris Cannam
date Fri, 07 Feb 2020 11:51:13 +0000
parents 7aeed7906520
children
rev   line source
Chris@69 1 /***********************************************************************
Chris@69 2 Copyright (c) 2006-2011, Skype Limited. All rights reserved.
Chris@69 3 Redistribution and use in source and binary forms, with or without
Chris@69 4 modification, are permitted provided that the following conditions
Chris@69 5 are met:
Chris@69 6 - Redistributions of source code must retain the above copyright notice,
Chris@69 7 this list of conditions and the following disclaimer.
Chris@69 8 - Redistributions in binary form must reproduce the above copyright
Chris@69 9 notice, this list of conditions and the following disclaimer in the
Chris@69 10 documentation and/or other materials provided with the distribution.
Chris@69 11 - Neither the name of Internet Society, IETF or IETF Trust, nor the
Chris@69 12 names of specific contributors, may be used to endorse or promote
Chris@69 13 products derived from this software without specific prior written
Chris@69 14 permission.
Chris@69 15 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
Chris@69 16 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
Chris@69 17 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
Chris@69 18 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
Chris@69 19 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
Chris@69 20 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
Chris@69 21 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
Chris@69 22 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
Chris@69 23 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
Chris@69 24 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
Chris@69 25 POSSIBILITY OF SUCH DAMAGE.
Chris@69 26 ***********************************************************************/
Chris@69 27
Chris@69 28 #ifdef HAVE_CONFIG_H
Chris@69 29 #include "config.h"
Chris@69 30 #endif
Chris@69 31
Chris@69 32 /*
Chris@69 33 Elliptic/Cauer filters designed with 0.1 dB passband ripple,
Chris@69 34 80 dB minimum stopband attenuation, and
Chris@69 35 [0.95 : 0.15 : 0.35] normalized cut off frequencies.
Chris@69 36 */
Chris@69 37
Chris@69 38 #include "main.h"
Chris@69 39
Chris@69 40 /* Helper function, interpolates the filter taps */
Chris@69 41 static OPUS_INLINE void silk_LP_interpolate_filter_taps(
Chris@69 42 opus_int32 B_Q28[ TRANSITION_NB ],
Chris@69 43 opus_int32 A_Q28[ TRANSITION_NA ],
Chris@69 44 const opus_int ind,
Chris@69 45 const opus_int32 fac_Q16
Chris@69 46 )
Chris@69 47 {
Chris@69 48 opus_int nb, na;
Chris@69 49
Chris@69 50 if( ind < TRANSITION_INT_NUM - 1 ) {
Chris@69 51 if( fac_Q16 > 0 ) {
Chris@69 52 if( fac_Q16 < 32768 ) { /* fac_Q16 is in range of a 16-bit int */
Chris@69 53 /* Piece-wise linear interpolation of B and A */
Chris@69 54 for( nb = 0; nb < TRANSITION_NB; nb++ ) {
Chris@69 55 B_Q28[ nb ] = silk_SMLAWB(
Chris@69 56 silk_Transition_LP_B_Q28[ ind ][ nb ],
Chris@69 57 silk_Transition_LP_B_Q28[ ind + 1 ][ nb ] -
Chris@69 58 silk_Transition_LP_B_Q28[ ind ][ nb ],
Chris@69 59 fac_Q16 );
Chris@69 60 }
Chris@69 61 for( na = 0; na < TRANSITION_NA; na++ ) {
Chris@69 62 A_Q28[ na ] = silk_SMLAWB(
Chris@69 63 silk_Transition_LP_A_Q28[ ind ][ na ],
Chris@69 64 silk_Transition_LP_A_Q28[ ind + 1 ][ na ] -
Chris@69 65 silk_Transition_LP_A_Q28[ ind ][ na ],
Chris@69 66 fac_Q16 );
Chris@69 67 }
Chris@69 68 } else { /* ( fac_Q16 - ( 1 << 16 ) ) is in range of a 16-bit int */
Chris@69 69 silk_assert( fac_Q16 - ( 1 << 16 ) == silk_SAT16( fac_Q16 - ( 1 << 16 ) ) );
Chris@69 70 /* Piece-wise linear interpolation of B and A */
Chris@69 71 for( nb = 0; nb < TRANSITION_NB; nb++ ) {
Chris@69 72 B_Q28[ nb ] = silk_SMLAWB(
Chris@69 73 silk_Transition_LP_B_Q28[ ind + 1 ][ nb ],
Chris@69 74 silk_Transition_LP_B_Q28[ ind + 1 ][ nb ] -
Chris@69 75 silk_Transition_LP_B_Q28[ ind ][ nb ],
Chris@69 76 fac_Q16 - ( (opus_int32)1 << 16 ) );
Chris@69 77 }
Chris@69 78 for( na = 0; na < TRANSITION_NA; na++ ) {
Chris@69 79 A_Q28[ na ] = silk_SMLAWB(
Chris@69 80 silk_Transition_LP_A_Q28[ ind + 1 ][ na ],
Chris@69 81 silk_Transition_LP_A_Q28[ ind + 1 ][ na ] -
Chris@69 82 silk_Transition_LP_A_Q28[ ind ][ na ],
Chris@69 83 fac_Q16 - ( (opus_int32)1 << 16 ) );
Chris@69 84 }
Chris@69 85 }
Chris@69 86 } else {
Chris@69 87 silk_memcpy( B_Q28, silk_Transition_LP_B_Q28[ ind ], TRANSITION_NB * sizeof( opus_int32 ) );
Chris@69 88 silk_memcpy( A_Q28, silk_Transition_LP_A_Q28[ ind ], TRANSITION_NA * sizeof( opus_int32 ) );
Chris@69 89 }
Chris@69 90 } else {
Chris@69 91 silk_memcpy( B_Q28, silk_Transition_LP_B_Q28[ TRANSITION_INT_NUM - 1 ], TRANSITION_NB * sizeof( opus_int32 ) );
Chris@69 92 silk_memcpy( A_Q28, silk_Transition_LP_A_Q28[ TRANSITION_INT_NUM - 1 ], TRANSITION_NA * sizeof( opus_int32 ) );
Chris@69 93 }
Chris@69 94 }
Chris@69 95
Chris@69 96 /* Low-pass filter with variable cutoff frequency based on */
Chris@69 97 /* piece-wise linear interpolation between elliptic filters */
Chris@69 98 /* Start by setting psEncC->mode <> 0; */
Chris@69 99 /* Deactivate by setting psEncC->mode = 0; */
Chris@69 100 void silk_LP_variable_cutoff(
Chris@69 101 silk_LP_state *psLP, /* I/O LP filter state */
Chris@69 102 opus_int16 *frame, /* I/O Low-pass filtered output signal */
Chris@69 103 const opus_int frame_length /* I Frame length */
Chris@69 104 )
Chris@69 105 {
Chris@69 106 opus_int32 B_Q28[ TRANSITION_NB ], A_Q28[ TRANSITION_NA ], fac_Q16 = 0;
Chris@69 107 opus_int ind = 0;
Chris@69 108
Chris@69 109 silk_assert( psLP->transition_frame_no >= 0 && psLP->transition_frame_no <= TRANSITION_FRAMES );
Chris@69 110
Chris@69 111 /* Run filter if needed */
Chris@69 112 if( psLP->mode != 0 ) {
Chris@69 113 /* Calculate index and interpolation factor for interpolation */
Chris@69 114 #if( TRANSITION_INT_STEPS == 64 )
Chris@69 115 fac_Q16 = silk_LSHIFT( TRANSITION_FRAMES - psLP->transition_frame_no, 16 - 6 );
Chris@69 116 #else
Chris@69 117 fac_Q16 = silk_DIV32_16( silk_LSHIFT( TRANSITION_FRAMES - psLP->transition_frame_no, 16 ), TRANSITION_FRAMES );
Chris@69 118 #endif
Chris@69 119 ind = silk_RSHIFT( fac_Q16, 16 );
Chris@69 120 fac_Q16 -= silk_LSHIFT( ind, 16 );
Chris@69 121
Chris@69 122 silk_assert( ind >= 0 );
Chris@69 123 silk_assert( ind < TRANSITION_INT_NUM );
Chris@69 124
Chris@69 125 /* Interpolate filter coefficients */
Chris@69 126 silk_LP_interpolate_filter_taps( B_Q28, A_Q28, ind, fac_Q16 );
Chris@69 127
Chris@69 128 /* Update transition frame number for next frame */
Chris@69 129 psLP->transition_frame_no = silk_LIMIT( psLP->transition_frame_no + psLP->mode, 0, TRANSITION_FRAMES );
Chris@69 130
Chris@69 131 /* ARMA low-pass filtering */
Chris@69 132 silk_assert( TRANSITION_NB == 3 && TRANSITION_NA == 2 );
Chris@69 133 silk_biquad_alt_stride1( frame, B_Q28, A_Q28, psLP->In_LP_State, frame, frame_length);
Chris@69 134 }
Chris@69 135 }