cannam@154: /*********************************************************************** cannam@154: Copyright (c) 2006-2011, Skype Limited. All rights reserved. cannam@154: Redistribution and use in source and binary forms, with or without cannam@154: modification, are permitted provided that the following conditions cannam@154: are met: cannam@154: - Redistributions of source code must retain the above copyright notice, cannam@154: this list of conditions and the following disclaimer. cannam@154: - Redistributions in binary form must reproduce the above copyright cannam@154: notice, this list of conditions and the following disclaimer in the cannam@154: documentation and/or other materials provided with the distribution. cannam@154: - Neither the name of Internet Society, IETF or IETF Trust, nor the cannam@154: names of specific contributors, may be used to endorse or promote cannam@154: products derived from this software without specific prior written cannam@154: permission. cannam@154: THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" cannam@154: AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE cannam@154: IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE cannam@154: ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE cannam@154: LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR cannam@154: CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF cannam@154: SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS cannam@154: INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN cannam@154: CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) cannam@154: ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE cannam@154: POSSIBILITY OF SUCH DAMAGE. cannam@154: ***********************************************************************/ cannam@154: cannam@154: #ifdef HAVE_CONFIG_H cannam@154: #include "config.h" cannam@154: #endif cannam@154: cannam@154: /* cannam@154: Elliptic/Cauer filters designed with 0.1 dB passband ripple, cannam@154: 80 dB minimum stopband attenuation, and cannam@154: [0.95 : 0.15 : 0.35] normalized cut off frequencies. cannam@154: */ cannam@154: cannam@154: #include "main.h" cannam@154: cannam@154: /* Helper function, interpolates the filter taps */ cannam@154: static OPUS_INLINE void silk_LP_interpolate_filter_taps( cannam@154: opus_int32 B_Q28[ TRANSITION_NB ], cannam@154: opus_int32 A_Q28[ TRANSITION_NA ], cannam@154: const opus_int ind, cannam@154: const opus_int32 fac_Q16 cannam@154: ) cannam@154: { cannam@154: opus_int nb, na; cannam@154: cannam@154: if( ind < TRANSITION_INT_NUM - 1 ) { cannam@154: if( fac_Q16 > 0 ) { cannam@154: if( fac_Q16 < 32768 ) { /* fac_Q16 is in range of a 16-bit int */ cannam@154: /* Piece-wise linear interpolation of B and A */ cannam@154: for( nb = 0; nb < TRANSITION_NB; nb++ ) { cannam@154: B_Q28[ nb ] = silk_SMLAWB( cannam@154: silk_Transition_LP_B_Q28[ ind ][ nb ], cannam@154: silk_Transition_LP_B_Q28[ ind + 1 ][ nb ] - cannam@154: silk_Transition_LP_B_Q28[ ind ][ nb ], cannam@154: fac_Q16 ); cannam@154: } cannam@154: for( na = 0; na < TRANSITION_NA; na++ ) { cannam@154: A_Q28[ na ] = silk_SMLAWB( cannam@154: silk_Transition_LP_A_Q28[ ind ][ na ], cannam@154: silk_Transition_LP_A_Q28[ ind + 1 ][ na ] - cannam@154: silk_Transition_LP_A_Q28[ ind ][ na ], cannam@154: fac_Q16 ); cannam@154: } cannam@154: } else { /* ( fac_Q16 - ( 1 << 16 ) ) is in range of a 16-bit int */ cannam@154: silk_assert( fac_Q16 - ( 1 << 16 ) == silk_SAT16( fac_Q16 - ( 1 << 16 ) ) ); cannam@154: /* Piece-wise linear interpolation of B and A */ cannam@154: for( nb = 0; nb < TRANSITION_NB; nb++ ) { cannam@154: B_Q28[ nb ] = silk_SMLAWB( cannam@154: silk_Transition_LP_B_Q28[ ind + 1 ][ nb ], cannam@154: silk_Transition_LP_B_Q28[ ind + 1 ][ nb ] - cannam@154: silk_Transition_LP_B_Q28[ ind ][ nb ], cannam@154: fac_Q16 - ( (opus_int32)1 << 16 ) ); cannam@154: } cannam@154: for( na = 0; na < TRANSITION_NA; na++ ) { cannam@154: A_Q28[ na ] = silk_SMLAWB( cannam@154: silk_Transition_LP_A_Q28[ ind + 1 ][ na ], cannam@154: silk_Transition_LP_A_Q28[ ind + 1 ][ na ] - cannam@154: silk_Transition_LP_A_Q28[ ind ][ na ], cannam@154: fac_Q16 - ( (opus_int32)1 << 16 ) ); cannam@154: } cannam@154: } cannam@154: } else { cannam@154: silk_memcpy( B_Q28, silk_Transition_LP_B_Q28[ ind ], TRANSITION_NB * sizeof( opus_int32 ) ); cannam@154: silk_memcpy( A_Q28, silk_Transition_LP_A_Q28[ ind ], TRANSITION_NA * sizeof( opus_int32 ) ); cannam@154: } cannam@154: } else { cannam@154: silk_memcpy( B_Q28, silk_Transition_LP_B_Q28[ TRANSITION_INT_NUM - 1 ], TRANSITION_NB * sizeof( opus_int32 ) ); cannam@154: silk_memcpy( A_Q28, silk_Transition_LP_A_Q28[ TRANSITION_INT_NUM - 1 ], TRANSITION_NA * sizeof( opus_int32 ) ); cannam@154: } cannam@154: } cannam@154: cannam@154: /* Low-pass filter with variable cutoff frequency based on */ cannam@154: /* piece-wise linear interpolation between elliptic filters */ cannam@154: /* Start by setting psEncC->mode <> 0; */ cannam@154: /* Deactivate by setting psEncC->mode = 0; */ cannam@154: void silk_LP_variable_cutoff( cannam@154: silk_LP_state *psLP, /* I/O LP filter state */ cannam@154: opus_int16 *frame, /* I/O Low-pass filtered output signal */ cannam@154: const opus_int frame_length /* I Frame length */ cannam@154: ) cannam@154: { cannam@154: opus_int32 B_Q28[ TRANSITION_NB ], A_Q28[ TRANSITION_NA ], fac_Q16 = 0; cannam@154: opus_int ind = 0; cannam@154: cannam@154: silk_assert( psLP->transition_frame_no >= 0 && psLP->transition_frame_no <= TRANSITION_FRAMES ); cannam@154: cannam@154: /* Run filter if needed */ cannam@154: if( psLP->mode != 0 ) { cannam@154: /* Calculate index and interpolation factor for interpolation */ cannam@154: #if( TRANSITION_INT_STEPS == 64 ) cannam@154: fac_Q16 = silk_LSHIFT( TRANSITION_FRAMES - psLP->transition_frame_no, 16 - 6 ); cannam@154: #else cannam@154: fac_Q16 = silk_DIV32_16( silk_LSHIFT( TRANSITION_FRAMES - psLP->transition_frame_no, 16 ), TRANSITION_FRAMES ); cannam@154: #endif cannam@154: ind = silk_RSHIFT( fac_Q16, 16 ); cannam@154: fac_Q16 -= silk_LSHIFT( ind, 16 ); cannam@154: cannam@154: silk_assert( ind >= 0 ); cannam@154: silk_assert( ind < TRANSITION_INT_NUM ); cannam@154: cannam@154: /* Interpolate filter coefficients */ cannam@154: silk_LP_interpolate_filter_taps( B_Q28, A_Q28, ind, fac_Q16 ); cannam@154: cannam@154: /* Update transition frame number for next frame */ cannam@154: psLP->transition_frame_no = silk_LIMIT( psLP->transition_frame_no + psLP->mode, 0, TRANSITION_FRAMES ); cannam@154: cannam@154: /* ARMA low-pass filtering */ cannam@154: silk_assert( TRANSITION_NB == 3 && TRANSITION_NA == 2 ); cannam@154: silk_biquad_alt_stride1( frame, B_Q28, A_Q28, psLP->In_LP_State, frame, frame_length); cannam@154: } cannam@154: }