mirror of
https://github.com/musix-org/musix-oss
synced 2024-11-14 06:40:21 +00:00
136 lines
6.4 KiB
C
136 lines
6.4 KiB
C
/***********************************************************************
|
|
Copyright (c) 2006-2011, Skype Limited. All rights reserved.
|
|
Redistribution and use in source and binary forms, with or without
|
|
modification, are permitted provided that the following conditions
|
|
are met:
|
|
- Redistributions of source code must retain the above copyright notice,
|
|
this list of conditions and the following disclaimer.
|
|
- Redistributions in binary form must reproduce the above copyright
|
|
notice, this list of conditions and the following disclaimer in the
|
|
documentation and/or other materials provided with the distribution.
|
|
- Neither the name of Internet Society, IETF or IETF Trust, nor the
|
|
names of specific contributors, may be used to endorse or promote
|
|
products derived from this software without specific prior written
|
|
permission.
|
|
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
|
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
|
|
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
|
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
|
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
|
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
|
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
POSSIBILITY OF SUCH DAMAGE.
|
|
***********************************************************************/
|
|
|
|
#ifdef HAVE_CONFIG_H
|
|
#include "config.h"
|
|
#endif
|
|
|
|
/*
|
|
Elliptic/Cauer filters designed with 0.1 dB passband ripple,
|
|
80 dB minimum stopband attenuation, and
|
|
[0.95 : 0.15 : 0.35] normalized cut off frequencies.
|
|
*/
|
|
|
|
#include "main.h"
|
|
|
|
/* Helper function, interpolates the filter taps */
|
|
static OPUS_INLINE void silk_LP_interpolate_filter_taps(
|
|
opus_int32 B_Q28[ TRANSITION_NB ],
|
|
opus_int32 A_Q28[ TRANSITION_NA ],
|
|
const opus_int ind,
|
|
const opus_int32 fac_Q16
|
|
)
|
|
{
|
|
opus_int nb, na;
|
|
|
|
if( ind < TRANSITION_INT_NUM - 1 ) {
|
|
if( fac_Q16 > 0 ) {
|
|
if( fac_Q16 < 32768 ) { /* fac_Q16 is in range of a 16-bit int */
|
|
/* Piece-wise linear interpolation of B and A */
|
|
for( nb = 0; nb < TRANSITION_NB; nb++ ) {
|
|
B_Q28[ nb ] = silk_SMLAWB(
|
|
silk_Transition_LP_B_Q28[ ind ][ nb ],
|
|
silk_Transition_LP_B_Q28[ ind + 1 ][ nb ] -
|
|
silk_Transition_LP_B_Q28[ ind ][ nb ],
|
|
fac_Q16 );
|
|
}
|
|
for( na = 0; na < TRANSITION_NA; na++ ) {
|
|
A_Q28[ na ] = silk_SMLAWB(
|
|
silk_Transition_LP_A_Q28[ ind ][ na ],
|
|
silk_Transition_LP_A_Q28[ ind + 1 ][ na ] -
|
|
silk_Transition_LP_A_Q28[ ind ][ na ],
|
|
fac_Q16 );
|
|
}
|
|
} else { /* ( fac_Q16 - ( 1 << 16 ) ) is in range of a 16-bit int */
|
|
silk_assert( fac_Q16 - ( 1 << 16 ) == silk_SAT16( fac_Q16 - ( 1 << 16 ) ) );
|
|
/* Piece-wise linear interpolation of B and A */
|
|
for( nb = 0; nb < TRANSITION_NB; nb++ ) {
|
|
B_Q28[ nb ] = silk_SMLAWB(
|
|
silk_Transition_LP_B_Q28[ ind + 1 ][ nb ],
|
|
silk_Transition_LP_B_Q28[ ind + 1 ][ nb ] -
|
|
silk_Transition_LP_B_Q28[ ind ][ nb ],
|
|
fac_Q16 - ( (opus_int32)1 << 16 ) );
|
|
}
|
|
for( na = 0; na < TRANSITION_NA; na++ ) {
|
|
A_Q28[ na ] = silk_SMLAWB(
|
|
silk_Transition_LP_A_Q28[ ind + 1 ][ na ],
|
|
silk_Transition_LP_A_Q28[ ind + 1 ][ na ] -
|
|
silk_Transition_LP_A_Q28[ ind ][ na ],
|
|
fac_Q16 - ( (opus_int32)1 << 16 ) );
|
|
}
|
|
}
|
|
} else {
|
|
silk_memcpy( B_Q28, silk_Transition_LP_B_Q28[ ind ], TRANSITION_NB * sizeof( opus_int32 ) );
|
|
silk_memcpy( A_Q28, silk_Transition_LP_A_Q28[ ind ], TRANSITION_NA * sizeof( opus_int32 ) );
|
|
}
|
|
} else {
|
|
silk_memcpy( B_Q28, silk_Transition_LP_B_Q28[ TRANSITION_INT_NUM - 1 ], TRANSITION_NB * sizeof( opus_int32 ) );
|
|
silk_memcpy( A_Q28, silk_Transition_LP_A_Q28[ TRANSITION_INT_NUM - 1 ], TRANSITION_NA * sizeof( opus_int32 ) );
|
|
}
|
|
}
|
|
|
|
/* Low-pass filter with variable cutoff frequency based on */
|
|
/* piece-wise linear interpolation between elliptic filters */
|
|
/* Start by setting psEncC->mode <> 0; */
|
|
/* Deactivate by setting psEncC->mode = 0; */
|
|
void silk_LP_variable_cutoff(
|
|
silk_LP_state *psLP, /* I/O LP filter state */
|
|
opus_int16 *frame, /* I/O Low-pass filtered output signal */
|
|
const opus_int frame_length /* I Frame length */
|
|
)
|
|
{
|
|
opus_int32 B_Q28[ TRANSITION_NB ], A_Q28[ TRANSITION_NA ], fac_Q16 = 0;
|
|
opus_int ind = 0;
|
|
|
|
silk_assert( psLP->transition_frame_no >= 0 && psLP->transition_frame_no <= TRANSITION_FRAMES );
|
|
|
|
/* Run filter if needed */
|
|
if( psLP->mode != 0 ) {
|
|
/* Calculate index and interpolation factor for interpolation */
|
|
#if( TRANSITION_INT_STEPS == 64 )
|
|
fac_Q16 = silk_LSHIFT( TRANSITION_FRAMES - psLP->transition_frame_no, 16 - 6 );
|
|
#else
|
|
fac_Q16 = silk_DIV32_16( silk_LSHIFT( TRANSITION_FRAMES - psLP->transition_frame_no, 16 ), TRANSITION_FRAMES );
|
|
#endif
|
|
ind = silk_RSHIFT( fac_Q16, 16 );
|
|
fac_Q16 -= silk_LSHIFT( ind, 16 );
|
|
|
|
silk_assert( ind >= 0 );
|
|
silk_assert( ind < TRANSITION_INT_NUM );
|
|
|
|
/* Interpolate filter coefficients */
|
|
silk_LP_interpolate_filter_taps( B_Q28, A_Q28, ind, fac_Q16 );
|
|
|
|
/* Update transition frame number for next frame */
|
|
psLP->transition_frame_no = silk_LIMIT( psLP->transition_frame_no + psLP->mode, 0, TRANSITION_FRAMES );
|
|
|
|
/* ARMA low-pass filtering */
|
|
silk_assert( TRANSITION_NB == 3 && TRANSITION_NA == 2 );
|
|
silk_biquad_alt( frame, B_Q28, A_Q28, psLP->In_LP_State, frame, frame_length, 1);
|
|
}
|
|
}
|