1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/media/libopus/silk/LP_variable_cutoff.c Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,135 @@
1.4 +/***********************************************************************
1.5 +Copyright (c) 2006-2011, Skype Limited. All rights reserved.
1.6 +Redistribution and use in source and binary forms, with or without
1.7 +modification, are permitted provided that the following conditions
1.8 +are met:
1.9 +- Redistributions of source code must retain the above copyright notice,
1.10 +this list of conditions and the following disclaimer.
1.11 +- Redistributions in binary form must reproduce the above copyright
1.12 +notice, this list of conditions and the following disclaimer in the
1.13 +documentation and/or other materials provided with the distribution.
1.14 +- Neither the name of Internet Society, IETF or IETF Trust, nor the
1.15 +names of specific contributors, may be used to endorse or promote
1.16 +products derived from this software without specific prior written
1.17 +permission.
1.18 +THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
1.19 +AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
1.20 +IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
1.21 +ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
1.22 +LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
1.23 +CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
1.24 +SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
1.25 +INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
1.26 +CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
1.27 +ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
1.28 +POSSIBILITY OF SUCH DAMAGE.
1.29 +***********************************************************************/
1.30 +
1.31 +#ifdef HAVE_CONFIG_H
1.32 +#include "config.h"
1.33 +#endif
1.34 +
1.35 +/*
1.36 + Elliptic/Cauer filters designed with 0.1 dB passband ripple,
1.37 + 80 dB minimum stopband attenuation, and
1.38 + [0.95 : 0.15 : 0.35] normalized cut off frequencies.
1.39 +*/
1.40 +
1.41 +#include "main.h"
1.42 +
1.43 +/* Helper function, interpolates the filter taps */
1.44 +static OPUS_INLINE void silk_LP_interpolate_filter_taps(
1.45 + opus_int32 B_Q28[ TRANSITION_NB ],
1.46 + opus_int32 A_Q28[ TRANSITION_NA ],
1.47 + const opus_int ind,
1.48 + const opus_int32 fac_Q16
1.49 +)
1.50 +{
1.51 + opus_int nb, na;
1.52 +
1.53 + if( ind < TRANSITION_INT_NUM - 1 ) {
1.54 + if( fac_Q16 > 0 ) {
1.55 + if( fac_Q16 < 32768 ) { /* fac_Q16 is in range of a 16-bit int */
1.56 + /* Piece-wise linear interpolation of B and A */
1.57 + for( nb = 0; nb < TRANSITION_NB; nb++ ) {
1.58 + B_Q28[ nb ] = silk_SMLAWB(
1.59 + silk_Transition_LP_B_Q28[ ind ][ nb ],
1.60 + silk_Transition_LP_B_Q28[ ind + 1 ][ nb ] -
1.61 + silk_Transition_LP_B_Q28[ ind ][ nb ],
1.62 + fac_Q16 );
1.63 + }
1.64 + for( na = 0; na < TRANSITION_NA; na++ ) {
1.65 + A_Q28[ na ] = silk_SMLAWB(
1.66 + silk_Transition_LP_A_Q28[ ind ][ na ],
1.67 + silk_Transition_LP_A_Q28[ ind + 1 ][ na ] -
1.68 + silk_Transition_LP_A_Q28[ ind ][ na ],
1.69 + fac_Q16 );
1.70 + }
1.71 + } else { /* ( fac_Q16 - ( 1 << 16 ) ) is in range of a 16-bit int */
1.72 + silk_assert( fac_Q16 - ( 1 << 16 ) == silk_SAT16( fac_Q16 - ( 1 << 16 ) ) );
1.73 + /* Piece-wise linear interpolation of B and A */
1.74 + for( nb = 0; nb < TRANSITION_NB; nb++ ) {
1.75 + B_Q28[ nb ] = silk_SMLAWB(
1.76 + silk_Transition_LP_B_Q28[ ind + 1 ][ nb ],
1.77 + silk_Transition_LP_B_Q28[ ind + 1 ][ nb ] -
1.78 + silk_Transition_LP_B_Q28[ ind ][ nb ],
1.79 + fac_Q16 - ( (opus_int32)1 << 16 ) );
1.80 + }
1.81 + for( na = 0; na < TRANSITION_NA; na++ ) {
1.82 + A_Q28[ na ] = silk_SMLAWB(
1.83 + silk_Transition_LP_A_Q28[ ind + 1 ][ na ],
1.84 + silk_Transition_LP_A_Q28[ ind + 1 ][ na ] -
1.85 + silk_Transition_LP_A_Q28[ ind ][ na ],
1.86 + fac_Q16 - ( (opus_int32)1 << 16 ) );
1.87 + }
1.88 + }
1.89 + } else {
1.90 + silk_memcpy( B_Q28, silk_Transition_LP_B_Q28[ ind ], TRANSITION_NB * sizeof( opus_int32 ) );
1.91 + silk_memcpy( A_Q28, silk_Transition_LP_A_Q28[ ind ], TRANSITION_NA * sizeof( opus_int32 ) );
1.92 + }
1.93 + } else {
1.94 + silk_memcpy( B_Q28, silk_Transition_LP_B_Q28[ TRANSITION_INT_NUM - 1 ], TRANSITION_NB * sizeof( opus_int32 ) );
1.95 + silk_memcpy( A_Q28, silk_Transition_LP_A_Q28[ TRANSITION_INT_NUM - 1 ], TRANSITION_NA * sizeof( opus_int32 ) );
1.96 + }
1.97 +}
1.98 +
1.99 +/* Low-pass filter with variable cutoff frequency based on */
1.100 +/* piece-wise linear interpolation between elliptic filters */
1.101 +/* Start by setting psEncC->mode <> 0; */
1.102 +/* Deactivate by setting psEncC->mode = 0; */
1.103 +void silk_LP_variable_cutoff(
1.104 + silk_LP_state *psLP, /* I/O LP filter state */
1.105 + opus_int16 *frame, /* I/O Low-pass filtered output signal */
1.106 + const opus_int frame_length /* I Frame length */
1.107 +)
1.108 +{
1.109 + opus_int32 B_Q28[ TRANSITION_NB ], A_Q28[ TRANSITION_NA ], fac_Q16 = 0;
1.110 + opus_int ind = 0;
1.111 +
1.112 + silk_assert( psLP->transition_frame_no >= 0 && psLP->transition_frame_no <= TRANSITION_FRAMES );
1.113 +
1.114 + /* Run filter if needed */
1.115 + if( psLP->mode != 0 ) {
1.116 + /* Calculate index and interpolation factor for interpolation */
1.117 +#if( TRANSITION_INT_STEPS == 64 )
1.118 + fac_Q16 = silk_LSHIFT( TRANSITION_FRAMES - psLP->transition_frame_no, 16 - 6 );
1.119 +#else
1.120 + fac_Q16 = silk_DIV32_16( silk_LSHIFT( TRANSITION_FRAMES - psLP->transition_frame_no, 16 ), TRANSITION_FRAMES );
1.121 +#endif
1.122 + ind = silk_RSHIFT( fac_Q16, 16 );
1.123 + fac_Q16 -= silk_LSHIFT( ind, 16 );
1.124 +
1.125 + silk_assert( ind >= 0 );
1.126 + silk_assert( ind < TRANSITION_INT_NUM );
1.127 +
1.128 + /* Interpolate filter coefficients */
1.129 + silk_LP_interpolate_filter_taps( B_Q28, A_Q28, ind, fac_Q16 );
1.130 +
1.131 + /* Update transition frame number for next frame */
1.132 + psLP->transition_frame_no = silk_LIMIT( psLP->transition_frame_no + psLP->mode, 0, TRANSITION_FRAMES );
1.133 +
1.134 + /* ARMA low-pass filtering */
1.135 + silk_assert( TRANSITION_NB == 3 && TRANSITION_NA == 2 );
1.136 + silk_biquad_alt( frame, B_Q28, A_Q28, psLP->In_LP_State, frame, frame_length, 1);
1.137 + }
1.138 +}
