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NLSF VQ now uses absolute error, and prediction

--- a/silk/NLSF_VQ.c

+++ b/silk/NLSF_VQ.c

@@ -33,36 +33,44 @@

 /* Compute quantization errors for an LPC_order element input vector for a VQ codebook */

 void silk_NLSF_VQ(

-    opus_int32                  err_Q26[],                      /* O    Quantization errors [K]                     */

+    opus_int32                  err_Q24[],                      /* O    Quantization errors [K]                     */

     const opus_int16            in_Q15[],                       /* I    Input vectors to be quantized [LPC_order]   */

     const opus_uint8            pCB_Q8[],                       /* I    Codebook vectors [K*LPC_order]              */

+    const opus_int16            pWght_Q9[],                     /* I    Codebook weights [K*LPC_order]              */

     const opus_int              K,                              /* I    Number of codebook vectors                  */

     const opus_int              LPC_order                       /* I    Number of LPCs                              */

 )

 {

-    opus_int        i, m;

-    opus_int32      diff_Q15, sum_error_Q30, sum_error_Q26;

+    opus_int         i, m;

+    opus_int32       diff_Q15, diffw_Q24, sum_error_Q24, pred_Q24;

+    const opus_int16 *w_Q9_ptr;

+    const opus_uint8 *cb_Q8_ptr;

-    silk_assert( LPC_order <= 16 );

     silk_assert( ( LPC_order & 1 ) == 0 );

     /* Loop over codebook */

+    cb_Q8_ptr = pCB_Q8;

+    w_Q9_ptr = pWght_Q9;

     for( i = 0; i < K; i++ ) {

-        sum_error_Q26 = 0;

-        for( m = 0; m < LPC_order; m += 2 ) {

-            /* Compute weighted squared quantization error for index m */

-            diff_Q15 = silk_SUB_LSHIFT32( in_Q15[ m ], (opus_int32)*pCB_Q8++, 7 ); /* range: [ -32767 : 32767 ]*/

-            sum_error_Q30 = silk_SMULBB( diff_Q15, diff_Q15 );

+        sum_error_Q24 = 0;

+        pred_Q24 = 0;

+        for( m = LPC_order-2; m >= 0; m -= 2 ) {

+            /* Compute weighted absolute predictive quantization error for index m + 1 */

+            diff_Q15 = silk_SUB_LSHIFT32( in_Q15[ m + 1 ], (opus_int32)cb_Q8_ptr[ m + 1 ], 7 ); /* range: [ -32767 : 32767 ]*/

+            diffw_Q24 = silk_SMULBB( diff_Q15, w_Q9_ptr[ m + 1 ] );

+            sum_error_Q24 = silk_ADD32( sum_error_Q24, silk_abs( silk_SUB_RSHIFT32( diffw_Q24, pred_Q24, 1 ) ) );

+            pred_Q24 = diffw_Q24;

-            /* Compute weighted squared quantization error for index m + 1 */

-            diff_Q15 = silk_SUB_LSHIFT32( in_Q15[m + 1], (opus_int32)*pCB_Q8++, 7 ); /* range: [ -32767 : 32767 ]*/

-            sum_error_Q30 = silk_SMLABB( sum_error_Q30, diff_Q15, diff_Q15 );

+            /* Compute weighted absolute predictive quantization error for index m */

+            diff_Q15 = silk_SUB_LSHIFT32( in_Q15[ m ], (opus_int32)cb_Q8_ptr[ m ], 7 ); /* range: [ -32767 : 32767 ]*/

+            diffw_Q24 = silk_SMULBB( diff_Q15, w_Q9_ptr[ m ] );

+            sum_error_Q24 = silk_ADD32( sum_error_Q24, silk_abs( silk_SUB_RSHIFT32( diffw_Q24, pred_Q24, 1 ) ) );

+            pred_Q24 = diffw_Q24;

-            sum_error_Q26 = silk_ADD_RSHIFT32( sum_error_Q26, sum_error_Q30, 4 );

-

-            silk_assert( sum_error_Q26 >= 0 );

-            silk_assert( sum_error_Q30 >= 0 );

+            silk_assert( sum_error_Q24 >= 0 );

         }

-        err_Q26[ i ] = sum_error_Q26;

+        err_Q24[ i ] = sum_error_Q24;

+        cb_Q8_ptr += LPC_order;

+        w_Q9_ptr += LPC_order;

     }

 }

--- a/silk/NLSF_decode.c

+++ b/silk/NLSF_decode.c

@@ -32,7 +32,7 @@

 #include "main.h"

 /* Predictive dequantizer for NLSF residuals */

-static OPUS_INLINE void silk_NLSF_residual_dequant(               /* O    Returns RD value in Q30                     */

+static OPUS_INLINE void silk_NLSF_residual_dequant(          /* O    Returns RD value in Q30                     */

           opus_int16         x_Q10[],                        /* O    Output [ order ]                            */

     const opus_int8          indices[],                      /* I    Quantization indices [ order ]              */

     const opus_uint8         pred_coef_Q8[],                 /* I    Backward predictor coefs [ order ]          */

--- a/silk/NLSF_encode.c

+++ b/silk/NLSF_encode.c

@@ -70,7 +70,7 @@

     /* First stage: VQ */

     ALLOC( err_Q26, psNLSF_CB->nVectors, opus_int32 );

-    silk_NLSF_VQ( err_Q26, pNLSF_Q15, psNLSF_CB->CB1_NLSF_Q8, psNLSF_CB->nVectors, psNLSF_CB->order );

+    silk_NLSF_VQ( err_Q26, pNLSF_Q15, psNLSF_CB->CB1_NLSF_Q8, psNLSF_CB->CB1_Wght_Q9, psNLSF_CB->nVectors, psNLSF_CB->order );

     /* Sort the quantization errors */

     ALLOC( tempIndices1, nSurvivors, opus_int );

--- a/silk/main.h

+++ b/silk/main.h

@@ -346,6 +346,7 @@

     opus_int32                  err_Q26[],                      /* O    Quantization errors [K]                     */

     const opus_int16            in_Q15[],                       /* I    Input vectors to be quantized [LPC_order]   */

     const opus_uint8            pCB_Q8[],                       /* I    Codebook vectors [K*LPC_order]              */

+    const opus_int16            pWght_Q9[],                     /* I    Codebook weights [K*LPC_order]              */

     const opus_int              K,                              /* I    Number of codebook vectors                  */

     const opus_int              LPC_order                       /* I    Number of LPCs                              */

 );