/* Convert adaptive Mid/Side representation to Left/Right stereo signal */ void silk_stereo_MS_to_LR( stereo_dec_state *state, /* I/O State */ opus_int16 x1[], /* I/O Left input signal, becomes mid signal */ opus_int16 x2[], /* I/O Right input signal, becomes side signal */ const opus_int32 pred_Q13[], /* I Predictors */ opus_int fs_kHz, /* I Samples rate (kHz) */ opus_int frame_length /* I Number of samples */ ) { opus_int n, denom_Q16, delta0_Q13, delta1_Q13; opus_int32 sum, diff, pred0_Q13, pred1_Q13; /* Buffering */ silk_memcpy( x1, state->sMid, 2 * sizeof( opus_int16 ) ); silk_memcpy( x2, state->sSide, 2 * sizeof( opus_int16 ) ); silk_memcpy( state->sMid, &x1[ frame_length ], 2 * sizeof( opus_int16 ) ); silk_memcpy( state->sSide, &x2[ frame_length ], 2 * sizeof( opus_int16 ) ); /* Interpolate predictors and add prediction to side channel */ pred0_Q13 = state->pred_prev_Q13[ 0 ]; pred1_Q13 = state->pred_prev_Q13[ 1 ]; denom_Q16 = silk_DIV32_16( (opus_int32)1 << 16, STEREO_INTERP_LEN_MS * fs_kHz ); delta0_Q13 = silk_RSHIFT_ROUND( silk_SMULBB( pred_Q13[ 0 ] - state->pred_prev_Q13[ 0 ], denom_Q16 ), 16 ); delta1_Q13 = silk_RSHIFT_ROUND( silk_SMULBB( pred_Q13[ 1 ] - state->pred_prev_Q13[ 1 ], denom_Q16 ), 16 ); for( n = 0; n < STEREO_INTERP_LEN_MS * fs_kHz; n++ ) { pred0_Q13 += delta0_Q13; pred1_Q13 += delta1_Q13; sum = silk_LSHIFT( silk_ADD_LSHIFT( x1[ n ] + x1[ n + 2 ], x1[ n + 1 ], 1 ), 9 ); /* Q11 */ sum = silk_SMLAWB( silk_LSHIFT( (opus_int32)x2[ n + 1 ], 8 ), sum, pred0_Q13 ); /* Q8 */ sum = silk_SMLAWB( sum, silk_LSHIFT( (opus_int32)x1[ n + 1 ], 11 ), pred1_Q13 ); /* Q8 */ x2[ n + 1 ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( sum, 8 ) ); } pred0_Q13 = pred_Q13[ 0 ]; pred1_Q13 = pred_Q13[ 1 ]; for( n = STEREO_INTERP_LEN_MS * fs_kHz; n < frame_length; n++ ) { sum = silk_LSHIFT( silk_ADD_LSHIFT( x1[ n ] + x1[ n + 2 ], x1[ n + 1 ], 1 ), 9 ); /* Q11 */ sum = silk_SMLAWB( silk_LSHIFT( (opus_int32)x2[ n + 1 ], 8 ), sum, pred0_Q13 ); /* Q8 */ sum = silk_SMLAWB( sum, silk_LSHIFT( (opus_int32)x1[ n + 1 ], 11 ), pred1_Q13 ); /* Q8 */ x2[ n + 1 ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( sum, 8 ) ); } state->pred_prev_Q13[ 0 ] = pred_Q13[ 0 ]; state->pred_prev_Q13[ 1 ] = pred_Q13[ 1 ]; /* Convert to left/right signals */ for( n = 0; n < frame_length; n++ ) { sum = x1[ n + 1 ] + (opus_int32)x2[ n + 1 ]; diff = x1[ n + 1 ] - (opus_int32)x2[ n + 1 ]; x1[ n + 1 ] = (opus_int16)silk_SAT16( sum ); x2[ n + 1 ] = (opus_int16)silk_SAT16( diff ); } }
/* Encodes signs of excitation */ void silk_encode_signs( ec_enc *psRangeEnc, /* I/O Compressor data structure */ const opus_int8 pulses[], /* I pulse signal */ opus_int length, /* I length of input */ const opus_int signalType, /* I Signal type */ const opus_int quantOffsetType, /* I Quantization offset type */ const opus_int sum_pulses[ MAX_NB_SHELL_BLOCKS ] /* I Sum of absolute pulses per block */ ) { opus_int i, j, p; opus_uint8 icdf[ 2 ]; const opus_int8 *q_ptr; const opus_uint8 *icdf_ptr; icdf[ 1 ] = 0; q_ptr = pulses; i = silk_SMULBB( 7, silk_ADD_LSHIFT( quantOffsetType, signalType, 1 ) ); icdf_ptr = &silk_sign_iCDF[ i ]; length = silk_RSHIFT( length + SHELL_CODEC_FRAME_LENGTH/2, LOG2_SHELL_CODEC_FRAME_LENGTH ); for( i = 0; i < length; i++ ) { p = sum_pulses[ i ]; if( p > 0 ) { icdf[ 0 ] = icdf_ptr[ silk_min( p & 0x1F, 6 ) ]; for( j = 0; j < SHELL_CODEC_FRAME_LENGTH; j++ ) { if( q_ptr[ j ] != 0 ) { ec_enc_icdf( psRangeEnc, silk_enc_map( q_ptr[ j ]), icdf, 8 ); } } } q_ptr += SHELL_CODEC_FRAME_LENGTH; } }
/* Decodes signs of excitation */ void silk_decode_signs( ec_dec *psRangeDec, /* I/O Compressor data structure */ opus_int pulses[], /* I/O pulse signal */ opus_int length, /* I length of input */ const opus_int signalType, /* I Signal type */ const opus_int quantOffsetType, /* I Quantization offset type */ const opus_int sum_pulses[ MAX_NB_SHELL_BLOCKS ] /* I Sum of absolute pulses per block */ ) { opus_int i, j, p; opus_uint8 icdf[ 2 ]; opus_int *q_ptr; const opus_uint8 *icdf_ptr; icdf[ 1 ] = 0; q_ptr = pulses; i = silk_SMULBB( 7, silk_ADD_LSHIFT( quantOffsetType, signalType, 1 ) ); icdf_ptr = &silk_sign_iCDF[ i ]; length = silk_RSHIFT( length + SHELL_CODEC_FRAME_LENGTH/2, LOG2_SHELL_CODEC_FRAME_LENGTH ); for( i = 0; i < length; i++ ) { p = sum_pulses[ i ]; if( p > 0 ) { icdf[ 0 ] = icdf_ptr[ silk_min( p & 0x1F, 6 ) ]; for( j = 0; j < SHELL_CODEC_FRAME_LENGTH; j++ ) { if( q_ptr[ j ] > 0 ) { /* attach sign */ #if 0 /* conditional implementation */ if( ec_dec_icdf( psRangeDec, icdf, 8 ) == 0 ) { q_ptr[ j ] = -q_ptr[ j ]; } #else /* implementation with shift, subtraction, multiplication */ q_ptr[ j ] *= silk_dec_map( ec_dec_icdf( psRangeDec, icdf, 8 ) ); #endif } } } q_ptr += SHELL_CODEC_FRAME_LENGTH; } }
/* Convert Left/Right stereo signal to adaptive Mid/Side representation */ void silk_stereo_LR_to_MS( stereo_enc_state *state, /* I/O State */ opus_int16 x1[], /* I/O Left input signal, becomes mid signal */ opus_int16 x2[], /* I/O Right input signal, becomes side signal */ opus_int8 ix[ 2 ][ 3 ], /* O Quantization indices */ opus_int8 *mid_only_flag, /* O Flag: only mid signal coded */ opus_int32 mid_side_rates_bps[], /* O Bitrates for mid and side signals */ opus_int32 total_rate_bps, /* I Total bitrate */ opus_int prev_speech_act_Q8, /* I Speech activity level in previous frame */ opus_int toMono, /* I Last frame before a stereo->mono transition */ opus_int fs_kHz, /* I Sample rate (kHz) */ opus_int frame_length /* I Number of samples */ ) { opus_int n, is10msFrame, denom_Q16, delta0_Q13, delta1_Q13; opus_int32 sum, diff, smooth_coef_Q16, pred_Q13[ 2 ], pred0_Q13, pred1_Q13; opus_int32 LP_ratio_Q14, HP_ratio_Q14, frac_Q16, frac_3_Q16, min_mid_rate_bps, width_Q14, w_Q24, deltaw_Q24; VARDECL( opus_int16, side ); VARDECL( opus_int16, LP_mid ); VARDECL( opus_int16, HP_mid ); VARDECL( opus_int16, LP_side ); VARDECL( opus_int16, HP_side ); opus_int16 *mid = &x1[ -2 ]; SAVE_STACK; ALLOC( side, frame_length + 2, opus_int16 ); /* Convert to basic mid/side signals */ for( n = 0; n < frame_length + 2; n++ ) { sum = x1[ n - 2 ] + (opus_int32)x2[ n - 2 ]; diff = x1[ n - 2 ] - (opus_int32)x2[ n - 2 ]; mid[ n ] = (opus_int16)silk_RSHIFT_ROUND( sum, 1 ); side[ n ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( diff, 1 ) ); } /* Buffering */ silk_memcpy( mid, state->sMid, 2 * sizeof( opus_int16 ) ); silk_memcpy( side, state->sSide, 2 * sizeof( opus_int16 ) ); silk_memcpy( state->sMid, &mid[ frame_length ], 2 * sizeof( opus_int16 ) ); silk_memcpy( state->sSide, &side[ frame_length ], 2 * sizeof( opus_int16 ) ); /* LP and HP filter mid signal */ ALLOC( LP_mid, frame_length, opus_int16 ); ALLOC( HP_mid, frame_length, opus_int16 ); for( n = 0; n < frame_length; n++ ) { sum = silk_RSHIFT_ROUND( silk_ADD_LSHIFT( mid[ n ] + mid[ n + 2 ], mid[ n + 1 ], 1 ), 2 ); LP_mid[ n ] = sum; HP_mid[ n ] = mid[ n + 1 ] - sum; } /* LP and HP filter side signal */ ALLOC( LP_side, frame_length, opus_int16 ); ALLOC( HP_side, frame_length, opus_int16 ); for( n = 0; n < frame_length; n++ ) { sum = silk_RSHIFT_ROUND( silk_ADD_LSHIFT( side[ n ] + side[ n + 2 ], side[ n + 1 ], 1 ), 2 ); LP_side[ n ] = sum; HP_side[ n ] = side[ n + 1 ] - sum; } /* Find energies and predictors */ is10msFrame = frame_length == 10 * fs_kHz; smooth_coef_Q16 = is10msFrame ? SILK_FIX_CONST( STEREO_RATIO_SMOOTH_COEF / 2, 16 ) : SILK_FIX_CONST( STEREO_RATIO_SMOOTH_COEF, 16 ); smooth_coef_Q16 = silk_SMULWB( silk_SMULBB( prev_speech_act_Q8, prev_speech_act_Q8 ), smooth_coef_Q16 ); pred_Q13[ 0 ] = silk_stereo_find_predictor( &LP_ratio_Q14, LP_mid, LP_side, &state->mid_side_amp_Q0[ 0 ], frame_length, smooth_coef_Q16 ); pred_Q13[ 1 ] = silk_stereo_find_predictor( &HP_ratio_Q14, HP_mid, HP_side, &state->mid_side_amp_Q0[ 2 ], frame_length, smooth_coef_Q16 ); /* Ratio of the norms of residual and mid signals */ frac_Q16 = silk_SMLABB( HP_ratio_Q14, LP_ratio_Q14, 3 ); frac_Q16 = silk_min( frac_Q16, SILK_FIX_CONST( 1, 16 ) ); /* Determine bitrate distribution between mid and side, and possibly reduce stereo width */ total_rate_bps -= is10msFrame ? 1200 : 600; /* Subtract approximate bitrate for coding stereo parameters */ if( total_rate_bps < 1 ) { total_rate_bps = 1; } min_mid_rate_bps = silk_SMLABB( 2000, fs_kHz, 900 ); silk_assert( min_mid_rate_bps < 32767 ); /* Default bitrate distribution: 8 parts for Mid and (5+3*frac) parts for Side. so: mid_rate = ( 8 / ( 13 + 3 * frac ) ) * total_ rate */ frac_3_Q16 = silk_MUL( 3, frac_Q16 ); mid_side_rates_bps[ 0 ] = silk_DIV32_varQ( total_rate_bps, SILK_FIX_CONST( 8 + 5, 16 ) + frac_3_Q16, 16+3 ); /* If Mid bitrate below minimum, reduce stereo width */ if( mid_side_rates_bps[ 0 ] < min_mid_rate_bps ) { mid_side_rates_bps[ 0 ] = min_mid_rate_bps; mid_side_rates_bps[ 1 ] = total_rate_bps - mid_side_rates_bps[ 0 ]; /* width = 4 * ( 2 * side_rate - min_rate ) / ( ( 1 + 3 * frac ) * min_rate ) */ width_Q14 = silk_DIV32_varQ( silk_LSHIFT( mid_side_rates_bps[ 1 ], 1 ) - min_mid_rate_bps, silk_SMULWB( SILK_FIX_CONST( 1, 16 ) + frac_3_Q16, min_mid_rate_bps ), 14+2 ); width_Q14 = silk_LIMIT( width_Q14, 0, SILK_FIX_CONST( 1, 14 ) ); } else { mid_side_rates_bps[ 1 ] = total_rate_bps - mid_side_rates_bps[ 0 ]; width_Q14 = SILK_FIX_CONST( 1, 14 ); } /* Smoother */ state->smth_width_Q14 = (opus_int16)silk_SMLAWB( state->smth_width_Q14, width_Q14 - state->smth_width_Q14, smooth_coef_Q16 ); /* At very low bitrates or for inputs that are nearly amplitude panned, switch to panned-mono coding */ *mid_only_flag = 0; if( toMono ) { /* Last frame before stereo->mono transition; collapse stereo width */ width_Q14 = 0; pred_Q13[ 0 ] = 0; pred_Q13[ 1 ] = 0; silk_stereo_quant_pred( pred_Q13, ix ); } else if( state->width_prev_Q14 == 0 && ( 8 * total_rate_bps < 13 * min_mid_rate_bps || silk_SMULWB( frac_Q16, state->smth_width_Q14 ) < SILK_FIX_CONST( 0.05, 14 ) ) ) { /* Code as panned-mono; previous frame already had zero width */ /* Scale down and quantize predictors */ pred_Q13[ 0 ] = silk_RSHIFT( silk_SMULBB( state->smth_width_Q14, pred_Q13[ 0 ] ), 14 ); pred_Q13[ 1 ] = silk_RSHIFT( silk_SMULBB( state->smth_width_Q14, pred_Q13[ 1 ] ), 14 ); silk_stereo_quant_pred( pred_Q13, ix ); /* Collapse stereo width */ width_Q14 = 0; pred_Q13[ 0 ] = 0; pred_Q13[ 1 ] = 0; mid_side_rates_bps[ 0 ] = total_rate_bps; mid_side_rates_bps[ 1 ] = 0; *mid_only_flag = 1; } else if( state->width_prev_Q14 != 0 && ( 8 * total_rate_bps < 11 * min_mid_rate_bps || silk_SMULWB( frac_Q16, state->smth_width_Q14 ) < SILK_FIX_CONST( 0.02, 14 ) ) ) { /* Transition to zero-width stereo */ /* Scale down and quantize predictors */ pred_Q13[ 0 ] = silk_RSHIFT( silk_SMULBB( state->smth_width_Q14, pred_Q13[ 0 ] ), 14 ); pred_Q13[ 1 ] = silk_RSHIFT( silk_SMULBB( state->smth_width_Q14, pred_Q13[ 1 ] ), 14 ); silk_stereo_quant_pred( pred_Q13, ix ); /* Collapse stereo width */ width_Q14 = 0; pred_Q13[ 0 ] = 0; pred_Q13[ 1 ] = 0; } else if( state->smth_width_Q14 > SILK_FIX_CONST( 0.95, 14 ) ) { /* Full-width stereo coding */ silk_stereo_quant_pred( pred_Q13, ix ); width_Q14 = SILK_FIX_CONST( 1, 14 ); } else { /* Reduced-width stereo coding; scale down and quantize predictors */ pred_Q13[ 0 ] = silk_RSHIFT( silk_SMULBB( state->smth_width_Q14, pred_Q13[ 0 ] ), 14 ); pred_Q13[ 1 ] = silk_RSHIFT( silk_SMULBB( state->smth_width_Q14, pred_Q13[ 1 ] ), 14 ); silk_stereo_quant_pred( pred_Q13, ix ); width_Q14 = state->smth_width_Q14; } /* Make sure to keep on encoding until the tapered output has been transmitted */ if( *mid_only_flag == 1 ) { state->silent_side_len += frame_length - STEREO_INTERP_LEN_MS * fs_kHz; if( state->silent_side_len < LA_SHAPE_MS * fs_kHz ) { *mid_only_flag = 0; } else { /* Limit to avoid wrapping around */ state->silent_side_len = 10000; } } else { state->silent_side_len = 0; } if( *mid_only_flag == 0 && mid_side_rates_bps[ 1 ] < 1 ) { mid_side_rates_bps[ 1 ] = 1; mid_side_rates_bps[ 0 ] = silk_max_int( 1, total_rate_bps - mid_side_rates_bps[ 1 ]); } /* Interpolate predictors and subtract prediction from side channel */ pred0_Q13 = -state->pred_prev_Q13[ 0 ]; pred1_Q13 = -state->pred_prev_Q13[ 1 ]; w_Q24 = silk_LSHIFT( state->width_prev_Q14, 10 ); denom_Q16 = silk_DIV32_16( (opus_int32)1 << 16, STEREO_INTERP_LEN_MS * fs_kHz ); delta0_Q13 = -silk_RSHIFT_ROUND( silk_SMULBB( pred_Q13[ 0 ] - state->pred_prev_Q13[ 0 ], denom_Q16 ), 16 ); delta1_Q13 = -silk_RSHIFT_ROUND( silk_SMULBB( pred_Q13[ 1 ] - state->pred_prev_Q13[ 1 ], denom_Q16 ), 16 ); deltaw_Q24 = silk_LSHIFT( silk_SMULWB( width_Q14 - state->width_prev_Q14, denom_Q16 ), 10 ); for( n = 0; n < STEREO_INTERP_LEN_MS * fs_kHz; n++ ) { pred0_Q13 += delta0_Q13; pred1_Q13 += delta1_Q13; w_Q24 += deltaw_Q24; sum = silk_LSHIFT( silk_ADD_LSHIFT( mid[ n ] + mid[ n + 2 ], mid[ n + 1 ], 1 ), 9 ); /* Q11 */ sum = silk_SMLAWB( silk_SMULWB( w_Q24, side[ n + 1 ] ), sum, pred0_Q13 ); /* Q8 */ sum = silk_SMLAWB( sum, silk_LSHIFT( (opus_int32)mid[ n + 1 ], 11 ), pred1_Q13 ); /* Q8 */ x2[ n - 1 ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( sum, 8 ) ); } pred0_Q13 = -pred_Q13[ 0 ]; pred1_Q13 = -pred_Q13[ 1 ]; w_Q24 = silk_LSHIFT( width_Q14, 10 ); for( n = STEREO_INTERP_LEN_MS * fs_kHz; n < frame_length; n++ ) { sum = silk_LSHIFT( silk_ADD_LSHIFT( mid[ n ] + mid[ n + 2 ], mid[ n + 1 ], 1 ), 9 ); /* Q11 */ sum = silk_SMLAWB( silk_SMULWB( w_Q24, side[ n + 1 ] ), sum, pred0_Q13 ); /* Q8 */ sum = silk_SMLAWB( sum, silk_LSHIFT( (opus_int32)mid[ n + 1 ], 11 ), pred1_Q13 ); /* Q8 */ x2[ n - 1 ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( sum, 8 ) ); } state->pred_prev_Q13[ 0 ] = (opus_int16)pred_Q13[ 0 ]; state->pred_prev_Q13[ 1 ] = (opus_int16)pred_Q13[ 1 ]; state->width_prev_Q14 = (opus_int16)width_Q14; RESTORE_STACK; }