silk/silk_VAD.c - platform/external/libopus - Gitiles

 /***********************************************************************
 Copyright (c) 2006-2011, Skype Limited. All rights reserved.
 Redistribution and use in source and binary forms, with or without
 modification, (subject to the limitations in the disclaimer below)
 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 Skype Limited, nor the names of specific
 contributors, may be used to endorse or promote products derived from
 this software without specific prior written permission.
 NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE GRANTED
 BY THIS LICENSE. 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

 #include <stdlib.h>
 #include "silk_main.h"

 /**********************************/
 /* Initialization of the Silk VAD */
 /**********************************/
 opus_int silk_VAD_Init(                              /* O    Return value, 0 if success                  */
     silk_VAD_state              *psSilk_VAD         /* I/O  Pointer to Silk VAD state                   */
 )
 {
     opus_int b, ret = 0;

     /* reset state memory */
     silk_memset( psSilk_VAD, 0, sizeof( silk_VAD_state ) );

     /* init noise levels */
     /* Initialize array with approx pink noise levels (psd proportional to inverse of frequency) */
     for( b = 0; b < VAD_N_BANDS; b++ ) {
         psSilk_VAD->NoiseLevelBias[ b ] = silk_max_32( silk_DIV32_16( VAD_NOISE_LEVELS_BIAS, b + 1 ), 1 );
     }

     /* Initialize state */
     for( b = 0; b < VAD_N_BANDS; b++ ) {
         psSilk_VAD->NL[ b ]     = silk_MUL( 100, psSilk_VAD->NoiseLevelBias[ b ] );
         psSilk_VAD->inv_NL[ b ] = silk_DIV32( silk_int32_MAX, psSilk_VAD->NL[ b ] );
     }
     psSilk_VAD->counter = 15;

     /* init smoothed energy-to-noise ratio*/
     for( b = 0; b < VAD_N_BANDS; b++ ) {
         psSilk_VAD->NrgRatioSmth_Q8[ b ] = 100 * 256;       /* 100 * 256 --> 20 dB SNR */
     }

     return( ret );
 }

 /* Weighting factors for tilt measure */
 static const opus_int32 tiltWeights[ VAD_N_BANDS ] = { 30000, 6000, -12000, -12000 };

 /***************************************/
 /* Get the speech activity level in Q8 */
 /***************************************/
 opus_int silk_VAD_GetSA_Q8(                          /* O    Return value, 0 if success                  */
     silk_encoder_state          *psEncC,            /* I/O  Encoder state                               */
     const opus_int16             pIn[]               /* I    PCM input                                   */
 )
 {
     opus_int   SA_Q15, pSNR_dB_Q7, input_tilt;
     opus_int   decimated_framelength, dec_subframe_length, dec_subframe_offset, SNR_Q7, i, b, s;
     opus_int32 sumSquared, smooth_coef_Q16;
     opus_int16 HPstateTmp;
     opus_int16 X[ VAD_N_BANDS ][ MAX_FRAME_LENGTH / 2 ];
     opus_int32 Xnrg[ VAD_N_BANDS ];
     opus_int32 NrgToNoiseRatio_Q8[ VAD_N_BANDS ];
     opus_int32 speech_nrg, x_tmp;
     opus_int   ret = 0;
     silk_VAD_state *psSilk_VAD = &psEncC->sVAD;

     /* Safety checks */
     silk_assert( VAD_N_BANDS == 4 );
     silk_assert( MAX_FRAME_LENGTH >= psEncC->frame_length );
     silk_assert( psEncC->frame_length <= 512 );
     silk_assert( psEncC->frame_length == 8 * silk_RSHIFT( psEncC->frame_length, 3 ) );

     /***********************/
     /* Filter and Decimate */
     /***********************/
     /* 0-8 kHz to 0-4 kHz and 4-8 kHz */
     silk_ana_filt_bank_1( pIn,          &psSilk_VAD->AnaState[  0 ], &X[ 0 ][ 0 ], &X[ 3 ][ 0 ], psEncC->frame_length );

     /* 0-4 kHz to 0-2 kHz and 2-4 kHz */
     silk_ana_filt_bank_1( &X[ 0 ][ 0 ], &psSilk_VAD->AnaState1[ 0 ], &X[ 0 ][ 0 ], &X[ 2 ][ 0 ], silk_RSHIFT( psEncC->frame_length, 1 ) );

     /* 0-2 kHz to 0-1 kHz and 1-2 kHz */
     silk_ana_filt_bank_1( &X[ 0 ][ 0 ], &psSilk_VAD->AnaState2[ 0 ], &X[ 0 ][ 0 ], &X[ 1 ][ 0 ], silk_RSHIFT( psEncC->frame_length, 2 ) );

     /*********************************************/
     /* HP filter on lowest band (differentiator) */
     /*********************************************/
     decimated_framelength = silk_RSHIFT( psEncC->frame_length, 3 );
     X[ 0 ][ decimated_framelength - 1 ] = silk_RSHIFT( X[ 0 ][ decimated_framelength - 1 ], 1 );
     HPstateTmp = X[ 0 ][ decimated_framelength - 1 ];
     for( i = decimated_framelength - 1; i > 0; i-- ) {
         X[ 0 ][ i - 1 ]  = silk_RSHIFT( X[ 0 ][ i - 1 ], 1 );
         X[ 0 ][ i ]     -= X[ 0 ][ i - 1 ];
     }
     X[ 0 ][ 0 ] -= psSilk_VAD->HPstate;
     psSilk_VAD->HPstate = HPstateTmp;

     /*************************************/
     /* Calculate the energy in each band */
     /*************************************/
     for( b = 0; b < VAD_N_BANDS; b++ ) {
         /* Find the decimated framelength in the non-uniformly divided bands */
         decimated_framelength = silk_RSHIFT( psEncC->frame_length, silk_min_int( VAD_N_BANDS - b, VAD_N_BANDS - 1 ) );

         /* Split length into subframe lengths */
         dec_subframe_length = silk_RSHIFT( decimated_framelength, VAD_INTERNAL_SUBFRAMES_LOG2 );
         dec_subframe_offset = 0;

         /* Compute energy per sub-frame */
         /* initialize with summed energy of last subframe */
         Xnrg[ b ] = psSilk_VAD->XnrgSubfr[ b ];
         for( s = 0; s < VAD_INTERNAL_SUBFRAMES; s++ ) {
             sumSquared = 0;
             for( i = 0; i < dec_subframe_length; i++ ) {
                 /* The energy will be less than dec_subframe_length * ( silk_int16_MIN / 8 ) ^ 2.            */
                 /* Therefore we can accumulate with no risk of overflow (unless dec_subframe_length > 128)  */
                 x_tmp = silk_RSHIFT( X[ b ][ i + dec_subframe_offset ], 3 );
                 sumSquared = silk_SMLABB( sumSquared, x_tmp, x_tmp );

                 /* Safety check */
                 silk_assert( sumSquared >= 0 );
             }

             /* Add/saturate summed energy of current subframe */
             if( s < VAD_INTERNAL_SUBFRAMES - 1 ) {
                 Xnrg[ b ] = silk_ADD_POS_SAT32( Xnrg[ b ], sumSquared );
             } else {
                 /* Look-ahead subframe */
                 Xnrg[ b ] = silk_ADD_POS_SAT32( Xnrg[ b ], silk_RSHIFT( sumSquared, 1 ) );
             }

             dec_subframe_offset += dec_subframe_length;
         }
         psSilk_VAD->XnrgSubfr[ b ] = sumSquared;
     }

     /********************/
     /* Noise estimation */
     /********************/
     silk_VAD_GetNoiseLevels( &Xnrg[ 0 ], psSilk_VAD );

     /***********************************************/
     /* Signal-plus-noise to noise ratio estimation */
     /***********************************************/
     sumSquared = 0;
     input_tilt = 0;
     for( b = 0; b < VAD_N_BANDS; b++ ) {
         speech_nrg = Xnrg[ b ] - psSilk_VAD->NL[ b ];
         if( speech_nrg > 0 ) {
             /* Divide, with sufficient resolution */
             if( ( Xnrg[ b ] & 0xFF800000 ) == 0 ) {
                 NrgToNoiseRatio_Q8[ b ] = silk_DIV32( silk_LSHIFT( Xnrg[ b ], 8 ), psSilk_VAD->NL[ b ] + 1 );
             } else {
                 NrgToNoiseRatio_Q8[ b ] = silk_DIV32( Xnrg[ b ], silk_RSHIFT( psSilk_VAD->NL[ b ], 8 ) + 1 );
             }

             /* Convert to log domain */
             SNR_Q7 = silk_lin2log( NrgToNoiseRatio_Q8[ b ] ) - 8 * 128;

             /* Sum-of-squares */
             sumSquared = silk_SMLABB( sumSquared, SNR_Q7, SNR_Q7 );          /* Q14 */

             /* Tilt measure */
             if( speech_nrg < ( 1 << 20 ) ) {
                 /* Scale down SNR value for small subband speech energies */
                 SNR_Q7 = silk_SMULWB( silk_LSHIFT( silk_SQRT_APPROX( speech_nrg ), 6 ), SNR_Q7 );
             }
             input_tilt = silk_SMLAWB( input_tilt, tiltWeights[ b ], SNR_Q7 );
         } else {
             NrgToNoiseRatio_Q8[ b ] = 256;
         }
     }

     /* Mean-of-squares */
     sumSquared = silk_DIV32_16( sumSquared, VAD_N_BANDS ); /* Q14 */

     /* Root-mean-square approximation, scale to dBs, and write to output pointer */
     pSNR_dB_Q7 = ( opus_int16 )( 3 * silk_SQRT_APPROX( sumSquared ) ); /* Q7 */

     /*********************************/
     /* Speech Probability Estimation */
     /*********************************/
     SA_Q15 = silk_sigm_Q15( silk_SMULWB( VAD_SNR_FACTOR_Q16, pSNR_dB_Q7 ) - VAD_NEGATIVE_OFFSET_Q5 );

     /**************************/
     /* Frequency Tilt Measure */
     /**************************/
     psEncC->input_tilt_Q15 = silk_LSHIFT( silk_sigm_Q15( input_tilt ) - 16384, 1 );

     /**************************************************/
     /* Scale the sigmoid output based on power levels */
     /**************************************************/
     speech_nrg = 0;
     for( b = 0; b < VAD_N_BANDS; b++ ) {
         /* Accumulate signal-without-noise energies, higher frequency bands have more weight */
         speech_nrg += ( b + 1 ) * silk_RSHIFT( Xnrg[ b ] - psSilk_VAD->NL[ b ], 4 );
     }

     /* Power scaling */
     if( speech_nrg <= 0 ) {
         SA_Q15 = silk_RSHIFT( SA_Q15, 1 );
     } else if( speech_nrg < 32768 ) {
         if( psEncC->frame_length == 10 * psEncC->fs_kHz ) {
             speech_nrg = silk_LSHIFT_SAT32( speech_nrg, 16 );
         } else {
             speech_nrg = silk_LSHIFT_SAT32( speech_nrg, 15 );
         }

         /* square-root */
         speech_nrg = silk_SQRT_APPROX( speech_nrg );
         SA_Q15 = silk_SMULWB( 32768 + speech_nrg, SA_Q15 );
     }

     /* Copy the resulting speech activity in Q8 */
     psEncC->speech_activity_Q8 = silk_min_int( silk_RSHIFT( SA_Q15, 7 ), silk_uint8_MAX );

     /***********************************/
     /* Energy Level and SNR estimation */
     /***********************************/
     /* Smoothing coefficient */
     smooth_coef_Q16 = silk_SMULWB( VAD_SNR_SMOOTH_COEF_Q18, silk_SMULWB( SA_Q15, SA_Q15 ) );

     if( psEncC->frame_length == 10 * psEncC->fs_kHz ) {
         smooth_coef_Q16 >>= 1;
     }

     for( b = 0; b < VAD_N_BANDS; b++ ) {
         /* compute smoothed energy-to-noise ratio per band */
         psSilk_VAD->NrgRatioSmth_Q8[ b ] = silk_SMLAWB( psSilk_VAD->NrgRatioSmth_Q8[ b ],
             NrgToNoiseRatio_Q8[ b ] - psSilk_VAD->NrgRatioSmth_Q8[ b ], smooth_coef_Q16 );

         /* signal to noise ratio in dB per band */
         SNR_Q7 = 3 * ( silk_lin2log( psSilk_VAD->NrgRatioSmth_Q8[b] ) - 8 * 128 );
         /* quality = sigmoid( 0.25 * ( SNR_dB - 16 ) ); */
         psEncC->input_quality_bands_Q15[ b ] = silk_sigm_Q15( silk_RSHIFT( SNR_Q7 - 16 * 128, 4 ) );
     }

     return( ret );
 }

 /**************************/
 /* Noise level estimation */
 /**************************/
 void silk_VAD_GetNoiseLevels(
     const opus_int32                 pX[ VAD_N_BANDS ],  /* I    subband energies                            */
     silk_VAD_state              *psSilk_VAD         /* I/O  Pointer to Silk VAD state                   */
 )
 {
     opus_int   k;
     opus_int32 nl, nrg, inv_nrg;
     opus_int   coef, min_coef;

     /* Initially faster smoothing */
     if( psSilk_VAD->counter < 1000 ) { /* 1000 = 20 sec */
         min_coef = silk_DIV32_16( silk_int16_MAX, silk_RSHIFT( psSilk_VAD->counter, 4 ) + 1 );
     } else {
         min_coef = 0;
     }

     for( k = 0; k < VAD_N_BANDS; k++ ) {
         /* Get old noise level estimate for current band */
         nl = psSilk_VAD->NL[ k ];
         silk_assert( nl >= 0 );

         /* Add bias */
         nrg = silk_ADD_POS_SAT32( pX[ k ], psSilk_VAD->NoiseLevelBias[ k ] );
         silk_assert( nrg > 0 );

         /* Invert energies */
         inv_nrg = silk_DIV32( silk_int32_MAX, nrg );
         silk_assert( inv_nrg >= 0 );

         /* Less update when subband energy is high */
         if( nrg > silk_LSHIFT( nl, 3 ) ) {
             coef = VAD_NOISE_LEVEL_SMOOTH_COEF_Q16 >> 3;
         } else if( nrg < nl ) {
             coef = VAD_NOISE_LEVEL_SMOOTH_COEF_Q16;
         } else {
             coef = silk_SMULWB( silk_SMULWW( inv_nrg, nl ), VAD_NOISE_LEVEL_SMOOTH_COEF_Q16 << 1 );
         }

         /* Initially faster smoothing */
         coef = silk_max_int( coef, min_coef );

         /* Smooth inverse energies */
         psSilk_VAD->inv_NL[ k ] = silk_SMLAWB( psSilk_VAD->inv_NL[ k ], inv_nrg - psSilk_VAD->inv_NL[ k ], coef );
         silk_assert( psSilk_VAD->inv_NL[ k ] >= 0 );

         /* Compute noise level by inverting again */
         nl = silk_DIV32( silk_int32_MAX, psSilk_VAD->inv_NL[ k ] );
         silk_assert( nl >= 0 );

         /* Limit noise levels (guarantee 7 bits of head room) */
         nl = silk_min( nl, 0x00FFFFFF );

         /* Store as part of state */
         psSilk_VAD->NL[ k ] = nl;
     }

     /* Increment frame counter */
     psSilk_VAD->counter++;
 }
	/***********************************************************************
	Copyright (c) 2006-2011, Skype Limited. All rights reserved.
	Redistribution and use in source and binary forms, with or without
	modification, (subject to the limitations in the disclaimer below)
	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 Skype Limited, nor the names of specific
	contributors, may be used to endorse or promote products derived from
	this software without specific prior written permission.
	NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE GRANTED
	BY THIS LICENSE. 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

	#include <stdlib.h>
	#include "silk_main.h"

	/**********************************/
	/* Initialization of the Silk VAD */
	/**********************************/
	opus_int silk_VAD_Init( /* O Return value, 0 if success */
	silk_VAD_state psSilk_VAD / I/O Pointer to Silk VAD state */
	)
	{
	opus_int b, ret = 0;

	/* reset state memory */
	silk_memset( psSilk_VAD, 0, sizeof( silk_VAD_state ) );

	/* init noise levels */
	/* Initialize array with approx pink noise levels (psd proportional to inverse of frequency) */
	for( b = 0; b < VAD_N_BANDS; b++ ) {
	psSilk_VAD->NoiseLevelBias[ b ] = silk_max_32( silk_DIV32_16( VAD_NOISE_LEVELS_BIAS, b + 1 ), 1 );
	}

	/* Initialize state */
	for( b = 0; b < VAD_N_BANDS; b++ ) {
	psSilk_VAD->NL[ b ] = silk_MUL( 100, psSilk_VAD->NoiseLevelBias[ b ] );
	psSilk_VAD->inv_NL[ b ] = silk_DIV32( silk_int32_MAX, psSilk_VAD->NL[ b ] );
	}
	psSilk_VAD->counter = 15;

	/* init smoothed energy-to-noise ratio*/
	for( b = 0; b < VAD_N_BANDS; b++ ) {
	psSilk_VAD->NrgRatioSmth_Q8[ b ] = 100 * 256; /* 100 * 256 --> 20 dB SNR */
	}

	return( ret );
	}

	/* Weighting factors for tilt measure */
	static const opus_int32 tiltWeights[ VAD_N_BANDS ] = { 30000, 6000, -12000, -12000 };

	/***************************************/
	/* Get the speech activity level in Q8 */
	/***************************************/
	opus_int silk_VAD_GetSA_Q8( /* O Return value, 0 if success */
	silk_encoder_state psEncC, / I/O Encoder state */
	const opus_int16 pIn[] /* I PCM input */
	)
	{
	opus_int SA_Q15, pSNR_dB_Q7, input_tilt;
	opus_int decimated_framelength, dec_subframe_length, dec_subframe_offset, SNR_Q7, i, b, s;
	opus_int32 sumSquared, smooth_coef_Q16;
	opus_int16 HPstateTmp;
	opus_int16 X[ VAD_N_BANDS ][ MAX_FRAME_LENGTH / 2 ];
	opus_int32 Xnrg[ VAD_N_BANDS ];
	opus_int32 NrgToNoiseRatio_Q8[ VAD_N_BANDS ];
	opus_int32 speech_nrg, x_tmp;
	opus_int ret = 0;
	silk_VAD_state *psSilk_VAD = &psEncC->sVAD;

	/* Safety checks */
	silk_assert( VAD_N_BANDS == 4 );
	silk_assert( MAX_FRAME_LENGTH >= psEncC->frame_length );
	silk_assert( psEncC->frame_length <= 512 );
	silk_assert( psEncC->frame_length == 8 * silk_RSHIFT( psEncC->frame_length, 3 ) );

	/***********************/
	/* Filter and Decimate */
	/***********************/
	/* 0-8 kHz to 0-4 kHz and 4-8 kHz */
	silk_ana_filt_bank_1( pIn, &psSilk_VAD->AnaState[ 0 ], &X[ 0 ][ 0 ], &X[ 3 ][ 0 ], psEncC->frame_length );

	/* 0-4 kHz to 0-2 kHz and 2-4 kHz */
	silk_ana_filt_bank_1( &X[ 0 ][ 0 ], &psSilk_VAD->AnaState1[ 0 ], &X[ 0 ][ 0 ], &X[ 2 ][ 0 ], silk_RSHIFT( psEncC->frame_length, 1 ) );

	/* 0-2 kHz to 0-1 kHz and 1-2 kHz */
	silk_ana_filt_bank_1( &X[ 0 ][ 0 ], &psSilk_VAD->AnaState2[ 0 ], &X[ 0 ][ 0 ], &X[ 1 ][ 0 ], silk_RSHIFT( psEncC->frame_length, 2 ) );

	/*********************************************/
	/* HP filter on lowest band (differentiator) */
	/*********************************************/
	decimated_framelength = silk_RSHIFT( psEncC->frame_length, 3 );
	X[ 0 ][ decimated_framelength - 1 ] = silk_RSHIFT( X[ 0 ][ decimated_framelength - 1 ], 1 );
	HPstateTmp = X[ 0 ][ decimated_framelength - 1 ];
	for( i = decimated_framelength - 1; i > 0; i-- ) {
	X[ 0 ][ i - 1 ] = silk_RSHIFT( X[ 0 ][ i - 1 ], 1 );
	X[ 0 ][ i ] -= X[ 0 ][ i - 1 ];
	}
	X[ 0 ][ 0 ] -= psSilk_VAD->HPstate;
	psSilk_VAD->HPstate = HPstateTmp;

	/*************************************/
	/* Calculate the energy in each band */
	/*************************************/
	for( b = 0; b < VAD_N_BANDS; b++ ) {
	/* Find the decimated framelength in the non-uniformly divided bands */
	decimated_framelength = silk_RSHIFT( psEncC->frame_length, silk_min_int( VAD_N_BANDS - b, VAD_N_BANDS - 1 ) );

	/* Split length into subframe lengths */
	dec_subframe_length = silk_RSHIFT( decimated_framelength, VAD_INTERNAL_SUBFRAMES_LOG2 );
	dec_subframe_offset = 0;

	/* Compute energy per sub-frame */
	/* initialize with summed energy of last subframe */
	Xnrg[ b ] = psSilk_VAD->XnrgSubfr[ b ];
	for( s = 0; s < VAD_INTERNAL_SUBFRAMES; s++ ) {
	sumSquared = 0;
	for( i = 0; i < dec_subframe_length; i++ ) {
	/* The energy will be less than dec_subframe_length * ( silk_int16_MIN / 8 ) ^ 2. */
	/* Therefore we can accumulate with no risk of overflow (unless dec_subframe_length > 128) */
	x_tmp = silk_RSHIFT( X[ b ][ i + dec_subframe_offset ], 3 );
	sumSquared = silk_SMLABB( sumSquared, x_tmp, x_tmp );

	/* Safety check */
	silk_assert( sumSquared >= 0 );
	}

	/* Add/saturate summed energy of current subframe */
	if( s < VAD_INTERNAL_SUBFRAMES - 1 ) {
	Xnrg[ b ] = silk_ADD_POS_SAT32( Xnrg[ b ], sumSquared );
	} else {
	/* Look-ahead subframe */
	Xnrg[ b ] = silk_ADD_POS_SAT32( Xnrg[ b ], silk_RSHIFT( sumSquared, 1 ) );
	}

	dec_subframe_offset += dec_subframe_length;
	}
	psSilk_VAD->XnrgSubfr[ b ] = sumSquared;
	}

	/********************/
	/* Noise estimation */
	/********************/
	silk_VAD_GetNoiseLevels( &Xnrg[ 0 ], psSilk_VAD );

	/***********************************************/
	/* Signal-plus-noise to noise ratio estimation */
	/***********************************************/
	sumSquared = 0;
	input_tilt = 0;
	for( b = 0; b < VAD_N_BANDS; b++ ) {
	speech_nrg = Xnrg[ b ] - psSilk_VAD->NL[ b ];
	if( speech_nrg > 0 ) {
	/* Divide, with sufficient resolution */
	if( ( Xnrg[ b ] & 0xFF800000 ) == 0 ) {
	NrgToNoiseRatio_Q8[ b ] = silk_DIV32( silk_LSHIFT( Xnrg[ b ], 8 ), psSilk_VAD->NL[ b ] + 1 );
	} else {
	NrgToNoiseRatio_Q8[ b ] = silk_DIV32( Xnrg[ b ], silk_RSHIFT( psSilk_VAD->NL[ b ], 8 ) + 1 );
	}

	/* Convert to log domain */
	SNR_Q7 = silk_lin2log( NrgToNoiseRatio_Q8[ b ] ) - 8 * 128;

	/* Sum-of-squares */
	sumSquared = silk_SMLABB( sumSquared, SNR_Q7, SNR_Q7 ); /* Q14 */

	/* Tilt measure */
	if( speech_nrg < ( 1 << 20 ) ) {
	/* Scale down SNR value for small subband speech energies */
	SNR_Q7 = silk_SMULWB( silk_LSHIFT( silk_SQRT_APPROX( speech_nrg ), 6 ), SNR_Q7 );
	}
	input_tilt = silk_SMLAWB( input_tilt, tiltWeights[ b ], SNR_Q7 );
	} else {
	NrgToNoiseRatio_Q8[ b ] = 256;
	}
	}

	/* Mean-of-squares */
	sumSquared = silk_DIV32_16( sumSquared, VAD_N_BANDS ); /* Q14 */

	/* Root-mean-square approximation, scale to dBs, and write to output pointer */
	pSNR_dB_Q7 = ( opus_int16 )( 3 * silk_SQRT_APPROX( sumSquared ) ); /* Q7 */

	/*********************************/
	/* Speech Probability Estimation */
	/*********************************/
	SA_Q15 = silk_sigm_Q15( silk_SMULWB( VAD_SNR_FACTOR_Q16, pSNR_dB_Q7 ) - VAD_NEGATIVE_OFFSET_Q5 );

	/**************************/
	/* Frequency Tilt Measure */
	/**************************/
	psEncC->input_tilt_Q15 = silk_LSHIFT( silk_sigm_Q15( input_tilt ) - 16384, 1 );

	/**************************************************/
	/* Scale the sigmoid output based on power levels */
	/**************************************************/
	speech_nrg = 0;
	for( b = 0; b < VAD_N_BANDS; b++ ) {
	/* Accumulate signal-without-noise energies, higher frequency bands have more weight */
	speech_nrg += ( b + 1 ) * silk_RSHIFT( Xnrg[ b ] - psSilk_VAD->NL[ b ], 4 );
	}

	/* Power scaling */
	if( speech_nrg <= 0 ) {
	SA_Q15 = silk_RSHIFT( SA_Q15, 1 );
	} else if( speech_nrg < 32768 ) {
	if( psEncC->frame_length == 10 * psEncC->fs_kHz ) {
	speech_nrg = silk_LSHIFT_SAT32( speech_nrg, 16 );
	} else {
	speech_nrg = silk_LSHIFT_SAT32( speech_nrg, 15 );
	}

	/* square-root */
	speech_nrg = silk_SQRT_APPROX( speech_nrg );
	SA_Q15 = silk_SMULWB( 32768 + speech_nrg, SA_Q15 );
	}

	/* Copy the resulting speech activity in Q8 */
	psEncC->speech_activity_Q8 = silk_min_int( silk_RSHIFT( SA_Q15, 7 ), silk_uint8_MAX );

	/***********************************/
	/* Energy Level and SNR estimation */
	/***********************************/
	/* Smoothing coefficient */
	smooth_coef_Q16 = silk_SMULWB( VAD_SNR_SMOOTH_COEF_Q18, silk_SMULWB( SA_Q15, SA_Q15 ) );

	if( psEncC->frame_length == 10 * psEncC->fs_kHz ) {
	smooth_coef_Q16 >>= 1;
	}

	for( b = 0; b < VAD_N_BANDS; b++ ) {
	/* compute smoothed energy-to-noise ratio per band */
	psSilk_VAD->NrgRatioSmth_Q8[ b ] = silk_SMLAWB( psSilk_VAD->NrgRatioSmth_Q8[ b ],
	NrgToNoiseRatio_Q8[ b ] - psSilk_VAD->NrgRatioSmth_Q8[ b ], smooth_coef_Q16 );

	/* signal to noise ratio in dB per band */
	SNR_Q7 = 3 * ( silk_lin2log( psSilk_VAD->NrgRatioSmth_Q8[b] ) - 8 * 128 );
	/* quality = sigmoid( 0.25 * ( SNR_dB - 16 ) ); */
	psEncC->input_quality_bands_Q15[ b ] = silk_sigm_Q15( silk_RSHIFT( SNR_Q7 - 16 * 128, 4 ) );
	}

	return( ret );
	}

	/**************************/
	/* Noise level estimation */
	/**************************/
	void silk_VAD_GetNoiseLevels(
	const opus_int32 pX[ VAD_N_BANDS ], /* I subband energies */
	silk_VAD_state psSilk_VAD / I/O Pointer to Silk VAD state */
	)
	{
	opus_int k;
	opus_int32 nl, nrg, inv_nrg;
	opus_int coef, min_coef;

	/* Initially faster smoothing */
	if( psSilk_VAD->counter < 1000 ) { /* 1000 = 20 sec */
	min_coef = silk_DIV32_16( silk_int16_MAX, silk_RSHIFT( psSilk_VAD->counter, 4 ) + 1 );
	} else {
	min_coef = 0;
	}

	for( k = 0; k < VAD_N_BANDS; k++ ) {
	/* Get old noise level estimate for current band */
	nl = psSilk_VAD->NL[ k ];
	silk_assert( nl >= 0 );

	/* Add bias */
	nrg = silk_ADD_POS_SAT32( pX[ k ], psSilk_VAD->NoiseLevelBias[ k ] );
	silk_assert( nrg > 0 );

	/* Invert energies */
	inv_nrg = silk_DIV32( silk_int32_MAX, nrg );
	silk_assert( inv_nrg >= 0 );

	/* Less update when subband energy is high */
	if( nrg > silk_LSHIFT( nl, 3 ) ) {
	coef = VAD_NOISE_LEVEL_SMOOTH_COEF_Q16 >> 3;
	} else if( nrg < nl ) {
	coef = VAD_NOISE_LEVEL_SMOOTH_COEF_Q16;
	} else {
	coef = silk_SMULWB( silk_SMULWW( inv_nrg, nl ), VAD_NOISE_LEVEL_SMOOTH_COEF_Q16 << 1 );
	}

	/* Initially faster smoothing */
	coef = silk_max_int( coef, min_coef );

	/* Smooth inverse energies */
	psSilk_VAD->inv_NL[ k ] = silk_SMLAWB( psSilk_VAD->inv_NL[ k ], inv_nrg - psSilk_VAD->inv_NL[ k ], coef );
	silk_assert( psSilk_VAD->inv_NL[ k ] >= 0 );

	/* Compute noise level by inverting again */
	nl = silk_DIV32( silk_int32_MAX, psSilk_VAD->inv_NL[ k ] );
	silk_assert( nl >= 0 );

	/* Limit noise levels (guarantee 7 bits of head room) */
	nl = silk_min( nl, 0x00FFFFFF );

	/* Store as part of state */
	psSilk_VAD->NL[ k ] = nl;
	}

	/* Increment frame counter */
	psSilk_VAD->counter++;
	}