Chris@69: /*********************************************************************** Chris@69: Copyright (c) 2006-2011, Skype Limited. All rights reserved. Chris@69: Redistribution and use in source and binary forms, with or without Chris@69: modification, are permitted provided that the following conditions Chris@69: are met: Chris@69: - Redistributions of source code must retain the above copyright notice, Chris@69: this list of conditions and the following disclaimer. Chris@69: - Redistributions in binary form must reproduce the above copyright Chris@69: notice, this list of conditions and the following disclaimer in the Chris@69: documentation and/or other materials provided with the distribution. Chris@69: - Neither the name of Internet Society, IETF or IETF Trust, nor the Chris@69: names of specific contributors, may be used to endorse or promote Chris@69: products derived from this software without specific prior written Chris@69: permission. Chris@69: THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" Chris@69: AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE Chris@69: IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE Chris@69: ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE Chris@69: LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR Chris@69: CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF Chris@69: SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS Chris@69: INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN Chris@69: CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) Chris@69: ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE Chris@69: POSSIBILITY OF SUCH DAMAGE. Chris@69: ***********************************************************************/ Chris@69: Chris@69: #ifdef HAVE_CONFIG_H Chris@69: #include "config.h" Chris@69: #endif Chris@69: Chris@69: /* Chris@69: Elliptic/Cauer filters designed with 0.1 dB passband ripple, Chris@69: 80 dB minimum stopband attenuation, and Chris@69: [0.95 : 0.15 : 0.35] normalized cut off frequencies. Chris@69: */ Chris@69: Chris@69: #include "main.h" Chris@69: Chris@69: /* Helper function, interpolates the filter taps */ Chris@69: static OPUS_INLINE void silk_LP_interpolate_filter_taps( Chris@69: opus_int32 B_Q28[ TRANSITION_NB ], Chris@69: opus_int32 A_Q28[ TRANSITION_NA ], Chris@69: const opus_int ind, Chris@69: const opus_int32 fac_Q16 Chris@69: ) Chris@69: { Chris@69: opus_int nb, na; Chris@69: Chris@69: if( ind < TRANSITION_INT_NUM - 1 ) { Chris@69: if( fac_Q16 > 0 ) { Chris@69: if( fac_Q16 < 32768 ) { /* fac_Q16 is in range of a 16-bit int */ Chris@69: /* Piece-wise linear interpolation of B and A */ Chris@69: for( nb = 0; nb < TRANSITION_NB; nb++ ) { Chris@69: B_Q28[ nb ] = silk_SMLAWB( Chris@69: silk_Transition_LP_B_Q28[ ind ][ nb ], Chris@69: silk_Transition_LP_B_Q28[ ind + 1 ][ nb ] - Chris@69: silk_Transition_LP_B_Q28[ ind ][ nb ], Chris@69: fac_Q16 ); Chris@69: } Chris@69: for( na = 0; na < TRANSITION_NA; na++ ) { Chris@69: A_Q28[ na ] = silk_SMLAWB( Chris@69: silk_Transition_LP_A_Q28[ ind ][ na ], Chris@69: silk_Transition_LP_A_Q28[ ind + 1 ][ na ] - Chris@69: silk_Transition_LP_A_Q28[ ind ][ na ], Chris@69: fac_Q16 ); Chris@69: } Chris@69: } else { /* ( fac_Q16 - ( 1 << 16 ) ) is in range of a 16-bit int */ Chris@69: silk_assert( fac_Q16 - ( 1 << 16 ) == silk_SAT16( fac_Q16 - ( 1 << 16 ) ) ); Chris@69: /* Piece-wise linear interpolation of B and A */ Chris@69: for( nb = 0; nb < TRANSITION_NB; nb++ ) { Chris@69: B_Q28[ nb ] = silk_SMLAWB( Chris@69: silk_Transition_LP_B_Q28[ ind + 1 ][ nb ], Chris@69: silk_Transition_LP_B_Q28[ ind + 1 ][ nb ] - Chris@69: silk_Transition_LP_B_Q28[ ind ][ nb ], Chris@69: fac_Q16 - ( (opus_int32)1 << 16 ) ); Chris@69: } Chris@69: for( na = 0; na < TRANSITION_NA; na++ ) { Chris@69: A_Q28[ na ] = silk_SMLAWB( Chris@69: silk_Transition_LP_A_Q28[ ind + 1 ][ na ], Chris@69: silk_Transition_LP_A_Q28[ ind + 1 ][ na ] - Chris@69: silk_Transition_LP_A_Q28[ ind ][ na ], Chris@69: fac_Q16 - ( (opus_int32)1 << 16 ) ); Chris@69: } Chris@69: } Chris@69: } else { Chris@69: silk_memcpy( B_Q28, silk_Transition_LP_B_Q28[ ind ], TRANSITION_NB * sizeof( opus_int32 ) ); Chris@69: silk_memcpy( A_Q28, silk_Transition_LP_A_Q28[ ind ], TRANSITION_NA * sizeof( opus_int32 ) ); Chris@69: } Chris@69: } else { Chris@69: silk_memcpy( B_Q28, silk_Transition_LP_B_Q28[ TRANSITION_INT_NUM - 1 ], TRANSITION_NB * sizeof( opus_int32 ) ); Chris@69: silk_memcpy( A_Q28, silk_Transition_LP_A_Q28[ TRANSITION_INT_NUM - 1 ], TRANSITION_NA * sizeof( opus_int32 ) ); Chris@69: } Chris@69: } Chris@69: Chris@69: /* Low-pass filter with variable cutoff frequency based on */ Chris@69: /* piece-wise linear interpolation between elliptic filters */ Chris@69: /* Start by setting psEncC->mode <> 0; */ Chris@69: /* Deactivate by setting psEncC->mode = 0; */ Chris@69: void silk_LP_variable_cutoff( Chris@69: silk_LP_state *psLP, /* I/O LP filter state */ Chris@69: opus_int16 *frame, /* I/O Low-pass filtered output signal */ Chris@69: const opus_int frame_length /* I Frame length */ Chris@69: ) Chris@69: { Chris@69: opus_int32 B_Q28[ TRANSITION_NB ], A_Q28[ TRANSITION_NA ], fac_Q16 = 0; Chris@69: opus_int ind = 0; Chris@69: Chris@69: silk_assert( psLP->transition_frame_no >= 0 && psLP->transition_frame_no <= TRANSITION_FRAMES ); Chris@69: Chris@69: /* Run filter if needed */ Chris@69: if( psLP->mode != 0 ) { Chris@69: /* Calculate index and interpolation factor for interpolation */ Chris@69: #if( TRANSITION_INT_STEPS == 64 ) Chris@69: fac_Q16 = silk_LSHIFT( TRANSITION_FRAMES - psLP->transition_frame_no, 16 - 6 ); Chris@69: #else Chris@69: fac_Q16 = silk_DIV32_16( silk_LSHIFT( TRANSITION_FRAMES - psLP->transition_frame_no, 16 ), TRANSITION_FRAMES ); Chris@69: #endif Chris@69: ind = silk_RSHIFT( fac_Q16, 16 ); Chris@69: fac_Q16 -= silk_LSHIFT( ind, 16 ); Chris@69: Chris@69: silk_assert( ind >= 0 ); Chris@69: silk_assert( ind < TRANSITION_INT_NUM ); Chris@69: Chris@69: /* Interpolate filter coefficients */ Chris@69: silk_LP_interpolate_filter_taps( B_Q28, A_Q28, ind, fac_Q16 ); Chris@69: Chris@69: /* Update transition frame number for next frame */ Chris@69: psLP->transition_frame_no = silk_LIMIT( psLP->transition_frame_no + psLP->mode, 0, TRANSITION_FRAMES ); Chris@69: Chris@69: /* ARMA low-pass filtering */ Chris@69: silk_assert( TRANSITION_NB == 3 && TRANSITION_NA == 2 ); Chris@69: silk_biquad_alt_stride1( frame, B_Q28, A_Q28, psLP->In_LP_State, frame, frame_length); Chris@69: } Chris@69: }