You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
135 lines
6.4 KiB
135 lines
6.4 KiB
/*********************************************************************** |
|
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_stride1( frame, B_Q28, A_Q28, psLP->In_LP_State, frame, frame_length); |
|
} |
|
}
|
|
|