diff options
author | Koen Vos <koen.vos@skype.net> | 2011-12-13 23:50:12 +0400 |
---|---|---|
committer | Jean-Marc Valin <jmvalin@jmvalin.ca> | 2011-12-13 23:50:12 +0400 |
commit | bbfc9c9ee5de680320aeae2f8bd981ebe7af6861 (patch) | |
tree | 0b1f05721de43ea51d17034e6383447f892dabf7 /silk/decode_core.c | |
parent | bf75c8ec4d0dded188bc7793de6da56c7ff0be1c (diff) |
Improves the accuracy such that it matches a float decoder much better
Diffstat (limited to 'silk/decode_core.c')
-rw-r--r-- | silk/decode_core.c | 31 |
1 files changed, 18 insertions, 13 deletions
diff --git a/silk/decode_core.c b/silk/decode_core.c index 6633143d..4b36aa07 100644 --- a/silk/decode_core.c +++ b/silk/decode_core.c @@ -45,12 +45,12 @@ void silk_decode_core( opus_int16 *A_Q12, *B_Q14, *pxq, A_Q12_tmp[ MAX_LPC_ORDER ]; opus_int16 sLTP[ MAX_FRAME_LENGTH ]; opus_int32 sLTP_Q15[ 2 * MAX_FRAME_LENGTH ]; - opus_int32 LTP_pred_Q13, LPC_pred_Q10, Gain_Q10, inv_gain_Q16, inv_gain_Q31, gain_adj_Q16, rand_seed, offset_Q10; + opus_int32 LTP_pred_Q13, LPC_pred_Q10, Gain_Q10, inv_gain_Q31, gain_adj_Q16, rand_seed, offset_Q10; opus_int32 *pred_lag_ptr, *pexc_Q10, *pres_Q10; opus_int32 res_Q10[ MAX_SUB_FRAME_LENGTH ]; opus_int32 sLPC_Q14[ MAX_SUB_FRAME_LENGTH + MAX_LPC_ORDER ]; - silk_assert( psDec->prev_inv_gain_Q16 != 0 ); + silk_assert( psDec->prev_inv_gain_Q31 != 0 ); offset_Q10 = silk_Quantization_Offsets_Q10[ psDec->indices.signalType >> 1 ][ psDec->indices.quantOffsetType ]; @@ -94,22 +94,23 @@ void silk_decode_core( signalType = psDec->indices.signalType; Gain_Q10 = silk_RSHIFT( psDecCtrl->Gains_Q16[ k ], 6 ); - inv_gain_Q16 = silk_INVERSE32_varQ( psDecCtrl->Gains_Q16[ k ], 32 ); + inv_gain_Q31 = silk_INVERSE32_varQ( psDecCtrl->Gains_Q16[ k ], 47 ); - /* Calculate Gain adjustment factor */ - gain_adj_Q16 = 1 << 16; - if( inv_gain_Q16 != psDec->prev_inv_gain_Q16 ) { - gain_adj_Q16 = silk_DIV32_varQ( inv_gain_Q16, psDec->prev_inv_gain_Q16, 16 ); + /* Calculate gain adjustment factor */ + if( inv_gain_Q31 != psDec->prev_inv_gain_Q31 ) { + gain_adj_Q16 = silk_DIV32_varQ( inv_gain_Q31, psDec->prev_inv_gain_Q31, 16 ); /* Scale short term state */ for( i = 0; i < MAX_LPC_ORDER; i++ ) { sLPC_Q14[ i ] = silk_SMULWW( gain_adj_Q16, sLPC_Q14[ i ] ); } + } else { + gain_adj_Q16 = 1 << 16; } /* Save inv_gain */ - silk_assert( inv_gain_Q16 != 0 ); - psDec->prev_inv_gain_Q16 = inv_gain_Q16; + silk_assert( inv_gain_Q31 != 0 ); + psDec->prev_inv_gain_Q31 = inv_gain_Q31; /* Avoid abrupt transition from voiced PLC to unvoiced normal decoding */ if( psDec->lossCnt && psDec->prevSignalType == TYPE_VOICED && @@ -140,7 +141,6 @@ void silk_decode_core( A_Q12, psDec->ltp_mem_length - start_idx, psDec->LPC_order ); /* After rewhitening the LTP state is unscaled */ - inv_gain_Q31 = silk_LSHIFT( inv_gain_Q16, 15 ); if( k == 0 ) { /* Do LTP downscaling to reduce inter-packet dependency */ inv_gain_Q31 = silk_LSHIFT( silk_SMULWB( inv_gain_Q31, psDecCtrl->LTP_scale_Q14 ), 2 ); @@ -164,7 +164,9 @@ void silk_decode_core( pred_lag_ptr = &sLTP_Q15[ sLTP_buf_idx - lag + LTP_ORDER / 2 ]; for( i = 0; i < psDec->subfr_length; i++ ) { /* Unrolled loop */ - LTP_pred_Q13 = silk_SMULWB( pred_lag_ptr[ 0 ], B_Q14[ 0 ] ); + /* Avoids introducing a bias because silk_SMLAWB() always rounds to -inf */ + LTP_pred_Q13 = 2; + LTP_pred_Q13 = silk_SMLAWB( LTP_pred_Q13, pred_lag_ptr[ 0 ], B_Q14[ 0 ] ); LTP_pred_Q13 = silk_SMLAWB( LTP_pred_Q13, pred_lag_ptr[ -1 ], B_Q14[ 1 ] ); LTP_pred_Q13 = silk_SMLAWB( LTP_pred_Q13, pred_lag_ptr[ -2 ], B_Q14[ 2 ] ); LTP_pred_Q13 = silk_SMLAWB( LTP_pred_Q13, pred_lag_ptr[ -3 ], B_Q14[ 3 ] ); @@ -185,7 +187,9 @@ void silk_decode_core( for( i = 0; i < psDec->subfr_length; i++ ) { /* Short-term prediction */ silk_assert( psDec->LPC_order == 10 || psDec->LPC_order == 16 ); - LPC_pred_Q10 = silk_SMULWB( sLPC_Q14[ MAX_LPC_ORDER + i - 1 ], A_Q12_tmp[ 0 ] ); + /* Avoids introducing a bias because silk_SMLAWB() always rounds to -inf */ + LPC_pred_Q10 = silk_RSHIFT( psDec->LPC_order, 1 ); + LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14[ MAX_LPC_ORDER + i - 1 ], A_Q12_tmp[ 0 ] ); LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14[ MAX_LPC_ORDER + i - 2 ], A_Q12_tmp[ 1 ] ); LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14[ MAX_LPC_ORDER + i - 3 ], A_Q12_tmp[ 2 ] ); LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14[ MAX_LPC_ORDER + i - 4 ], A_Q12_tmp[ 3 ] ); @@ -207,11 +211,12 @@ void silk_decode_core( /* Add prediction to LPC excitation */ sLPC_Q14[ MAX_LPC_ORDER + i ] = silk_LSHIFT( silk_ADD32( pres_Q10[ i ], LPC_pred_Q10 ), 4 ); - /* Scale with Gain */ + /* Scale with gain */ pxq[ i ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( silk_SMULWW( sLPC_Q14[ MAX_LPC_ORDER + i ], Gain_Q10 ), 8 ) ); } /* DEBUG_STORE_DATA( dec.pcm, pxq, psDec->subfr_length * sizeof( opus_int16 ) ) */ + /* Update LPC filter state */ silk_memcpy( sLPC_Q14, &sLPC_Q14[ psDec->subfr_length ], MAX_LPC_ORDER * sizeof( opus_int32 ) ); pexc_Q10 += psDec->subfr_length; |