105 lines
5.1 KiB
C
Executable File
105 lines
5.1 KiB
C
Executable File
/***********************************************************************
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Copyright (c) 2006-2012, 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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#include "SKP_Silk_main_FLP.h"
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#include "SKP_Silk_tuning_parameters.h"
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#if HIGH_PASS_INPUT
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/* High-pass filter with cutoff frequency adaptation based on pitch lag statistics */
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void SKP_Silk_HP_variable_cutoff_FLP(
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SKP_Silk_encoder_state_FLP *psEnc, /* I/O Encoder state FLP */
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SKP_Silk_encoder_control_FLP *psEncCtrl, /* I/O Encoder control FLP */
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SKP_int16 *out, /* O High-pass filtered output signal */
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const SKP_int16 *in /* I Input signal */
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)
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{
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SKP_float pitch_freq_Hz, pitch_freq_log, quality, delta_freq, smth_coef, Fc, r;
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SKP_int32 B_Q28[ 3 ], A_Q28[ 2 ];
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/*********************************************/
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/* Estimate low end of pitch frequency range */
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/*********************************************/
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if( psEnc->sCmn.prev_sigtype == SIG_TYPE_VOICED ) {
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/* Difference, in log domain */
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pitch_freq_Hz = 1e3f * psEnc->sCmn.fs_kHz / psEnc->sCmn.prevLag;
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pitch_freq_log = SKP_Silk_log2( pitch_freq_Hz );
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/* Adjustment based on quality */
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quality = psEncCtrl->input_quality_bands[ 0 ];
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pitch_freq_log -= quality * quality * ( pitch_freq_log - SKP_Silk_log2( VARIABLE_HP_MIN_FREQ ) );
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pitch_freq_log += 0.5f * ( 0.6f - quality );
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delta_freq = pitch_freq_log - psEnc->variable_HP_smth1;
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if( delta_freq < 0.0 ) {
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/* Less smoothing for decreasing pitch frequency, to track something close to the minimum */
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delta_freq *= 3.0f;
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}
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/* Limit delta, to reduce impact of outliers */
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delta_freq = SKP_LIMIT_float( delta_freq, -VARIABLE_HP_MAX_DELTA_FREQ, VARIABLE_HP_MAX_DELTA_FREQ );
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/* Update smoother */
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smth_coef = VARIABLE_HP_SMTH_COEF1 * psEnc->speech_activity;
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psEnc->variable_HP_smth1 += smth_coef * delta_freq;
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}
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/* Second smoother */
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psEnc->variable_HP_smth2 += VARIABLE_HP_SMTH_COEF2 * ( psEnc->variable_HP_smth1 - psEnc->variable_HP_smth2 );
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/* Convert from log scale to Hertz */
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psEncCtrl->pitch_freq_low_Hz = ( SKP_float )pow( 2.0f, psEnc->variable_HP_smth2 );
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/* Limit frequency range */
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psEncCtrl->pitch_freq_low_Hz = SKP_LIMIT_float( psEncCtrl->pitch_freq_low_Hz, VARIABLE_HP_MIN_FREQ, VARIABLE_HP_MAX_FREQ );
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/*******************************/
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/* Compute filter coefficients */
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/*******************************/
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/* Compute cut-off frequency, in radians */
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Fc = ( SKP_float )( 0.45f * 2.0f * 3.14159265359 * psEncCtrl->pitch_freq_low_Hz / ( 1e3f * psEnc->sCmn.fs_kHz ) );
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/* 2nd order ARMA coefficients */
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r = 1.0f - 0.92f * Fc;
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/* b = r * [1; -2; 1]; */
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/* a = [1; -2 * r * (1 - 0.5 * Fc^2); r^2]; */
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B_Q28[ 0 ] = SKP_float2int( ( 1 << 28 ) * r );
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B_Q28[ 1 ] = SKP_float2int( ( 1 << 28 ) * -2.0f * r );
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B_Q28[ 2 ] = B_Q28[ 0 ];
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A_Q28[ 0 ] = SKP_float2int( ( 1 << 28 ) * -2.0f * r * ( 1.0f - 0.5f * Fc * Fc ) );
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A_Q28[ 1 ] = SKP_float2int( ( 1 << 28 ) * r * r );
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/********************/
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/* High-pass filter */
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/********************/
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SKP_Silk_biquad_alt( in, B_Q28, A_Q28, psEnc->sCmn.In_HP_State, out, psEnc->sCmn.frame_length );
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}
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#endif // HIGH_PASS_INPUT
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