/* Resample with a 2x downsampler (optional), a 2nd order AR filter followed by FIR interpolation */ void SKP_Silk_resampler_private_down_FIR( void *SS, /* I/O: Resampler state */ SKP_int16 out[], /* O: Output signal */ const SKP_int16 in[], /* I: Input signal */ SKP_int32 inLen /* I: Number of input samples */ ) { SKP_Silk_resampler_state_struct *S = (SKP_Silk_resampler_state_struct *)SS; SKP_int32 nSamplesIn; SKP_int32 max_index_Q16, index_increment_Q16; SKP_int16 buf1[ RESAMPLER_MAX_BATCH_SIZE_IN / 2 ]; SKP_int32 buf2[ RESAMPLER_MAX_BATCH_SIZE_IN + RESAMPLER_DOWN_ORDER_FIR ]; const SKP_int16 *FIR_Coefs; /* Copy buffered samples to start of buffer */ SKP_memcpy( buf2, S->sFIR, RESAMPLER_DOWN_ORDER_FIR * sizeof( SKP_int32 ) ); FIR_Coefs = &S->Coefs[ 2 ]; /* Iterate over blocks of frameSizeIn input samples */ index_increment_Q16 = S->invRatio_Q16; while( 1 ) { nSamplesIn = SKP_min( inLen, S->batchSize ); if( S->input2x == 1 ) { /* Downsample 2x */ SKP_Silk_resampler_down2( S->sDown2, buf1, in, nSamplesIn ); nSamplesIn = SKP_RSHIFT32( nSamplesIn, 1 ); /* Second-order AR filter (output in Q8) */ SKP_Silk_resampler_private_AR2( S->sIIR, &buf2[ RESAMPLER_DOWN_ORDER_FIR ], buf1, S->Coefs, nSamplesIn ); } else { /* Second-order AR filter (output in Q8) */ SKP_Silk_resampler_private_AR2( S->sIIR, &buf2[ RESAMPLER_DOWN_ORDER_FIR ], in, S->Coefs, nSamplesIn ); } max_index_Q16 = SKP_LSHIFT32( nSamplesIn, 16 ); /* Interpolate filtered signal */ if( S->FIR_Fracs == 1 ) { out = SKP_Silk_resampler_private_down_FIR_INTERPOL0(out, buf2, FIR_Coefs, max_index_Q16, index_increment_Q16); } else { out = SKP_Silk_resampler_private_down_FIR_INTERPOL1(out, buf2, FIR_Coefs, max_index_Q16, index_increment_Q16, S->FIR_Fracs); } in += nSamplesIn << S->input2x; inLen -= nSamplesIn << S->input2x; if( inLen > S->input2x ) { /* More iterations to do; copy last part of filtered signal to beginning of buffer */ SKP_memcpy( buf2, &buf2[ nSamplesIn ], RESAMPLER_DOWN_ORDER_FIR * sizeof( SKP_int32 ) ); } else { break; } } /* Copy last part of filtered signal to the state for the next call */ SKP_memcpy( S->sFIR, &buf2[ nSamplesIn ], RESAMPLER_DOWN_ORDER_FIR * sizeof( SKP_int32 ) ); }
/* Downsample by a factor 3, low quality */ void SKP_Silk_resampler_down3( SKP_int32 *S, /* I/O: State vector [ 8 ] */ SKP_int16 *out, /* O: Output signal [ floor(inLen/3) ] */ const SKP_int16 *in, /* I: Input signal [ inLen ] */ SKP_int32 inLen /* I: Number of input samples */ ) { SKP_int32 nSamplesIn, counter, res_Q6; SKP_int32 buf[ RESAMPLER_MAX_BATCH_SIZE_IN + ORDER_FIR ]; SKP_int32 *buf_ptr; /* Copy buffered samples to start of buffer */ SKP_memcpy( buf, S, ORDER_FIR * sizeof( SKP_int32 ) ); /* Iterate over blocks of frameSizeIn input samples */ while( 1 ) { nSamplesIn = SKP_min( inLen, RESAMPLER_MAX_BATCH_SIZE_IN ); /* Second-order AR filter (output in Q8) */ SKP_Silk_resampler_private_AR2( &S[ ORDER_FIR ], &buf[ ORDER_FIR ], in, SKP_Silk_Resampler_1_3_COEFS_LQ, nSamplesIn ); /* Interpolate filtered signal */ buf_ptr = buf; counter = nSamplesIn; while( counter > 2 ) { /* Inner product */ res_Q6 = SKP_SMULWB( SKP_ADD32( buf_ptr[ 0 ], buf_ptr[ 5 ] ), SKP_Silk_Resampler_1_3_COEFS_LQ[ 2 ] ); res_Q6 = SKP_SMLAWB( res_Q6, SKP_ADD32( buf_ptr[ 1 ], buf_ptr[ 4 ] ), SKP_Silk_Resampler_1_3_COEFS_LQ[ 3 ] ); res_Q6 = SKP_SMLAWB( res_Q6, SKP_ADD32( buf_ptr[ 2 ], buf_ptr[ 3 ] ), SKP_Silk_Resampler_1_3_COEFS_LQ[ 4 ] ); /* Scale down, saturate and store in output array */ *out++ = (SKP_int16)SKP_SAT16( SKP_RSHIFT_ROUND( res_Q6, 6 ) ); buf_ptr += 3; counter -= 3; } in += nSamplesIn; inLen -= nSamplesIn; if( inLen > 0 ) { /* More iterations to do; copy last part of filtered signal to beginning of buffer */ SKP_memcpy( buf, &buf[ nSamplesIn ], ORDER_FIR * sizeof( SKP_int32 ) ); } else { break; } } /* Copy last part of filtered signal to the state for the next call */ SKP_memcpy( S, &buf[ nSamplesIn ], ORDER_FIR * sizeof( SKP_int32 ) ); }
/* Resample with a 2x downsampler (optional), a 2nd order AR filter followed by FIR interpolation */ void SKP_Silk_resampler_private_down_FIR( void *SS, /* I/O: Resampler state */ SKP_int16 out[], /* O: Output signal */ const SKP_int16 in[], /* I: Input signal */ SKP_int32 inLen /* I: Number of input samples */ ) { SKP_Silk_resampler_state_struct *S = (SKP_Silk_resampler_state_struct *)SS; SKP_int32 nSamplesIn, interpol_ind; SKP_int32 max_index_Q16, index_Q16, index_increment_Q16, res_Q6; SKP_int16 buf1[ RESAMPLER_MAX_BATCH_SIZE_IN / 2 ]; SKP_int32 buf2[ RESAMPLER_MAX_BATCH_SIZE_IN + RESAMPLER_DOWN_ORDER_FIR ]; SKP_int32 *buf_ptr; const SKP_int16 *interpol_ptr, *FIR_Coefs; /* Copy buffered samples to start of buffer */ SKP_memcpy( buf2, S->sFIR, RESAMPLER_DOWN_ORDER_FIR * sizeof( SKP_int32 ) ); FIR_Coefs = &S->Coefs[ 2 ]; /* Iterate over blocks of frameSizeIn input samples */ index_increment_Q16 = S->invRatio_Q16; while( 1 ) { nSamplesIn = SKP_min( inLen, S->batchSize ); if( S->input2x == 1 ) { /* Downsample 2x */ SKP_Silk_resampler_down2( S->sDown2, buf1, in, nSamplesIn ); nSamplesIn = SKP_RSHIFT32( nSamplesIn, 1 ); /* Second-order AR filter (output in Q8) */ SKP_Silk_resampler_private_AR2( S->sIIR, &buf2[ RESAMPLER_DOWN_ORDER_FIR ], buf1, S->Coefs, nSamplesIn ); } else { /* Second-order AR filter (output in Q8) */ SKP_Silk_resampler_private_AR2( S->sIIR, &buf2[ RESAMPLER_DOWN_ORDER_FIR ], in, S->Coefs, nSamplesIn ); } max_index_Q16 = SKP_LSHIFT32( nSamplesIn, 16 ); /* Interpolate filtered signal */ if( S->FIR_Fracs == 1 ) { for( index_Q16 = 0; index_Q16 < max_index_Q16; index_Q16 += index_increment_Q16 ) { /* Integer part gives pointer to buffered input */ buf_ptr = buf2 + SKP_RSHIFT( index_Q16, 16 ); /* Inner product */ res_Q6 = SKP_SMULWB( SKP_ADD32( buf_ptr[ 0 ], buf_ptr[ 11 ] ), FIR_Coefs[ 0 ] ); res_Q6 = SKP_SMLAWB( res_Q6, SKP_ADD32( buf_ptr[ 1 ], buf_ptr[ 10 ] ), FIR_Coefs[ 1 ] ); res_Q6 = SKP_SMLAWB( res_Q6, SKP_ADD32( buf_ptr[ 2 ], buf_ptr[ 9 ] ), FIR_Coefs[ 2 ] ); res_Q6 = SKP_SMLAWB( res_Q6, SKP_ADD32( buf_ptr[ 3 ], buf_ptr[ 8 ] ), FIR_Coefs[ 3 ] ); res_Q6 = SKP_SMLAWB( res_Q6, SKP_ADD32( buf_ptr[ 4 ], buf_ptr[ 7 ] ), FIR_Coefs[ 4 ] ); res_Q6 = SKP_SMLAWB( res_Q6, SKP_ADD32( buf_ptr[ 5 ], buf_ptr[ 6 ] ), FIR_Coefs[ 5 ] ); /* Scale down, saturate and store in output array */ *out++ = (SKP_int16)SKP_SAT16( SKP_RSHIFT_ROUND( res_Q6, 6 ) ); } } else { for( index_Q16 = 0; index_Q16 < max_index_Q16; index_Q16 += index_increment_Q16 ) { /* Integer part gives pointer to buffered input */ buf_ptr = buf2 + SKP_RSHIFT( index_Q16, 16 ); /* Fractional part gives interpolation coefficients */ interpol_ind = SKP_SMULWB( index_Q16 & 0xFFFF, S->FIR_Fracs ); /* Inner product */ interpol_ptr = &FIR_Coefs[ RESAMPLER_DOWN_ORDER_FIR / 2 * interpol_ind ]; res_Q6 = SKP_SMULWB( buf_ptr[ 0 ], interpol_ptr[ 0 ] ); res_Q6 = SKP_SMLAWB( res_Q6, buf_ptr[ 1 ], interpol_ptr[ 1 ] ); res_Q6 = SKP_SMLAWB( res_Q6, buf_ptr[ 2 ], interpol_ptr[ 2 ] ); res_Q6 = SKP_SMLAWB( res_Q6, buf_ptr[ 3 ], interpol_ptr[ 3 ] ); res_Q6 = SKP_SMLAWB( res_Q6, buf_ptr[ 4 ], interpol_ptr[ 4 ] ); res_Q6 = SKP_SMLAWB( res_Q6, buf_ptr[ 5 ], interpol_ptr[ 5 ] ); interpol_ptr = &FIR_Coefs[ RESAMPLER_DOWN_ORDER_FIR / 2 * ( S->FIR_Fracs - 1 - interpol_ind ) ]; res_Q6 = SKP_SMLAWB( res_Q6, buf_ptr[ 11 ], interpol_ptr[ 0 ] ); res_Q6 = SKP_SMLAWB( res_Q6, buf_ptr[ 10 ], interpol_ptr[ 1 ] ); res_Q6 = SKP_SMLAWB( res_Q6, buf_ptr[ 9 ], interpol_ptr[ 2 ] ); res_Q6 = SKP_SMLAWB( res_Q6, buf_ptr[ 8 ], interpol_ptr[ 3 ] ); res_Q6 = SKP_SMLAWB( res_Q6, buf_ptr[ 7 ], interpol_ptr[ 4 ] ); res_Q6 = SKP_SMLAWB( res_Q6, buf_ptr[ 6 ], interpol_ptr[ 5 ] ); /* Scale down, saturate and store in output array */ *out++ = (SKP_int16)SKP_SAT16( SKP_RSHIFT_ROUND( res_Q6, 6 ) ); } } in += nSamplesIn << S->input2x; inLen -= nSamplesIn << S->input2x; if( inLen > S->input2x ) { /* More iterations to do; copy last part of filtered signal to beginning of buffer */ SKP_memcpy( buf2, &buf2[ nSamplesIn ], RESAMPLER_DOWN_ORDER_FIR * sizeof( SKP_int32 ) ); } else { break; } } /* Copy last part of filtered signal to the state for the next call */ SKP_memcpy( S->sFIR, &buf2[ nSamplesIn ], RESAMPLER_DOWN_ORDER_FIR * sizeof( SKP_int32 ) ); }