195 lines
9.3 KiB
C
195 lines
9.3 KiB
C
/***********************************************************************
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Copyright (c) 2006-2011, Skype Limited. All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, (subject to the limitations in the disclaimer below)
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are permitted provided that the following conditions are met:
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- Redistributions of source code must retain the above copyright notice,
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this list of conditions and the following disclaimer.
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- Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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- Neither the name of Skype Limited, nor the names of specific
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contributors, may be used to endorse or promote products derived from
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this software without specific prior written permission.
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NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE GRANTED
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BY THIS LICENSE. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
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CONTRIBUTORS ''AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
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BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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***********************************************************************/
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/*
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Elliptic/Cauer filters designed with 0.1 dB passband ripple,
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80 dB minimum stopband attenuation, and
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[0.95 : 0.15 : 0.35] normalized cut off frequencies.
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*/
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#include "SKP_Silk_main.h"
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#if SWITCH_TRANSITION_FILTERING
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/* Helper function, that interpolates the filter taps */
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SKP_INLINE void SKP_Silk_LP_interpolate_filter_taps(
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SKP_int32 B_Q28[ TRANSITION_NB ],
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SKP_int32 A_Q28[ TRANSITION_NA ],
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const SKP_int ind,
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const SKP_int32 fac_Q16
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)
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{
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SKP_int nb, na;
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if( ind < TRANSITION_INT_NUM - 1 ) {
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if( fac_Q16 > 0 ) {
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if( fac_Q16 == SKP_SAT16( fac_Q16 ) ) { /* fac_Q16 is in range of a 16-bit int */
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/* Piece-wise linear interpolation of B and A */
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for( nb = 0; nb < TRANSITION_NB; nb++ ) {
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B_Q28[ nb ] = SKP_SMLAWB(
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SKP_Silk_Transition_LP_B_Q28[ ind ][ nb ],
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SKP_Silk_Transition_LP_B_Q28[ ind + 1 ][ nb ] -
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SKP_Silk_Transition_LP_B_Q28[ ind ][ nb ],
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fac_Q16 );
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}
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for( na = 0; na < TRANSITION_NA; na++ ) {
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A_Q28[ na ] = SKP_SMLAWB(
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SKP_Silk_Transition_LP_A_Q28[ ind ][ na ],
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SKP_Silk_Transition_LP_A_Q28[ ind + 1 ][ na ] -
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SKP_Silk_Transition_LP_A_Q28[ ind ][ na ],
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fac_Q16 );
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}
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} else if( fac_Q16 == ( 1 << 15 ) ) { /* Neither fac_Q16 nor ( ( 1 << 16 ) - fac_Q16 ) is in range of a 16-bit int */
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/* Piece-wise linear interpolation of B and A */
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for( nb = 0; nb < TRANSITION_NB; nb++ ) {
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B_Q28[ nb ] = SKP_RSHIFT(
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SKP_Silk_Transition_LP_B_Q28[ ind ][ nb ] +
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SKP_Silk_Transition_LP_B_Q28[ ind + 1 ][ nb ],
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1 );
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}
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for( na = 0; na < TRANSITION_NA; na++ ) {
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A_Q28[ na ] = SKP_RSHIFT(
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SKP_Silk_Transition_LP_A_Q28[ ind ][ na ] +
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SKP_Silk_Transition_LP_A_Q28[ ind + 1 ][ na ],
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1 );
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}
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} else { /* ( ( 1 << 16 ) - fac_Q16 ) is in range of a 16-bit int */
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SKP_assert( ( ( 1 << 16 ) - fac_Q16 ) == SKP_SAT16( ( ( 1 << 16 ) - fac_Q16) ) );
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/* Piece-wise linear interpolation of B and A */
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for( nb = 0; nb < TRANSITION_NB; nb++ ) {
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B_Q28[ nb ] = SKP_SMLAWB(
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SKP_Silk_Transition_LP_B_Q28[ ind + 1 ][ nb ],
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SKP_Silk_Transition_LP_B_Q28[ ind ][ nb ] -
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SKP_Silk_Transition_LP_B_Q28[ ind + 1 ][ nb ],
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( 1 << 16 ) - fac_Q16 );
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}
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for( na = 0; na < TRANSITION_NA; na++ ) {
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A_Q28[ na ] = SKP_SMLAWB(
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SKP_Silk_Transition_LP_A_Q28[ ind + 1 ][ na ],
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SKP_Silk_Transition_LP_A_Q28[ ind ][ na ] -
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SKP_Silk_Transition_LP_A_Q28[ ind + 1 ][ na ],
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( 1 << 16 ) - fac_Q16 );
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}
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}
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} else {
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SKP_memcpy( B_Q28, SKP_Silk_Transition_LP_B_Q28[ ind ], TRANSITION_NB * sizeof( SKP_int32 ) );
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SKP_memcpy( A_Q28, SKP_Silk_Transition_LP_A_Q28[ ind ], TRANSITION_NA * sizeof( SKP_int32 ) );
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}
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} else {
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SKP_memcpy( B_Q28, SKP_Silk_Transition_LP_B_Q28[ TRANSITION_INT_NUM - 1 ], TRANSITION_NB * sizeof( SKP_int32 ) );
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SKP_memcpy( A_Q28, SKP_Silk_Transition_LP_A_Q28[ TRANSITION_INT_NUM - 1 ], TRANSITION_NA * sizeof( SKP_int32 ) );
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}
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}
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/* Low-pass filter with variable cutoff frequency based on */
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/* piece-wise linear interpolation between elliptic filters */
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/* Start by setting psEncC->transition_frame_no = 1; */
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/* Deactivate by setting psEncC->transition_frame_no = 0; */
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void SKP_Silk_LP_variable_cutoff(
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SKP_Silk_LP_state *psLP, /* I/O LP filter state */
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SKP_int16 *out, /* O Low-pass filtered output signal */
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const SKP_int16 *in, /* I Input signal */
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const SKP_int frame_length /* I Frame length */
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)
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{
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SKP_int32 B_Q28[ TRANSITION_NB ], A_Q28[ TRANSITION_NA ], fac_Q16 = 0;
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SKP_int ind = 0;
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SKP_assert( psLP->transition_frame_no >= 0 );
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SKP_assert( ( ( ( psLP->transition_frame_no <= TRANSITION_FRAMES_DOWN ) && ( psLP->mode == 0 ) ) ||
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( ( psLP->transition_frame_no <= TRANSITION_FRAMES_UP ) && ( psLP->mode == 1 ) ) ) );
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/* Interpolate filter coefficients if needed */
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if( psLP->transition_frame_no > 0 ) {
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if( psLP->mode == 0 ) {
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if( psLP->transition_frame_no < TRANSITION_FRAMES_DOWN ) {
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/* Calculate index and interpolation factor for interpolation */
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#if( TRANSITION_INT_STEPS_DOWN == 32 )
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fac_Q16 = SKP_LSHIFT( psLP->transition_frame_no, 16 - 5 );
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#else
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fac_Q16 = SKP_DIV32_16( SKP_LSHIFT( psLP->transition_frame_no, 16 ), TRANSITION_INT_STEPS_DOWN );
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#endif
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ind = SKP_RSHIFT( fac_Q16, 16 );
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fac_Q16 -= SKP_LSHIFT( ind, 16 );
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SKP_assert( ind >= 0 );
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SKP_assert( ind < TRANSITION_INT_NUM );
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/* Interpolate filter coefficients */
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SKP_Silk_LP_interpolate_filter_taps( B_Q28, A_Q28, ind, fac_Q16 );
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/* Increment transition frame number for next frame */
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psLP->transition_frame_no++;
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} else {
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SKP_assert( psLP->transition_frame_no == TRANSITION_FRAMES_DOWN );
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/* End of transition phase */
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SKP_Silk_LP_interpolate_filter_taps( B_Q28, A_Q28, TRANSITION_INT_NUM - 1, 0 );
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}
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} else {
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SKP_assert( psLP->mode == 1 );
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if( psLP->transition_frame_no < TRANSITION_FRAMES_UP ) {
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/* Calculate index and interpolation factor for interpolation */
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#if( TRANSITION_INT_STEPS_UP == 64 )
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fac_Q16 = SKP_LSHIFT( TRANSITION_FRAMES_UP - psLP->transition_frame_no, 16 - 6 );
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#else
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fac_Q16 = SKP_DIV32_16( SKP_LSHIFT( TRANSITION_FRAMES_UP - psLP->transition_frame_no, 16 ), TRANSITION_INT_STEPS_UP );
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#endif
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ind = SKP_RSHIFT( fac_Q16, 16 );
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fac_Q16 -= SKP_LSHIFT( ind, 16 );
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SKP_assert( ind >= 0 );
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SKP_assert( ind < TRANSITION_INT_NUM );
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/* Interpolate filter coefficients */
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SKP_Silk_LP_interpolate_filter_taps( B_Q28, A_Q28, ind, fac_Q16 );
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/* Increment transition frame number for next frame */
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psLP->transition_frame_no++;
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} else {
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SKP_assert( psLP->transition_frame_no == TRANSITION_FRAMES_UP );
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/* End of transition phase */
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SKP_Silk_LP_interpolate_filter_taps( B_Q28, A_Q28, 0, 0 );
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}
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}
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}
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if( psLP->transition_frame_no > 0 ) {
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/* ARMA low-pass filtering */
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SKP_assert( TRANSITION_NB == 3 && TRANSITION_NA == 2 );
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SKP_Silk_biquad_alt( in, B_Q28, A_Q28, psLP->In_LP_State, out, frame_length );
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} else {
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/* Instead of using the filter, copy input directly to output */
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SKP_memcpy( out, in, frame_length * sizeof( SKP_int16 ) );
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}
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}
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#endif
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