From 4817473b559d0464e7a695110745690c6f161dd0 Mon Sep 17 00:00:00 2001
From: Sandesh Venkatesh <sandesh.venkatesh@ittiam.com>
Date: Thu, 6 Feb 2025 12:39:29 +0530
Subject: [PATCH] Fix for 3GPP issue 1251: Basop Encoder: Spectral holes
 between 2-4 kHz and spectral differences for Unified Stereo @24kbps

Link #1251
---
 lib_com/stat_com.h   |  2 +-
 lib_enc/fd_cng_enc.c | 42 ++++++++++++++++++++++++++++++------------
 2 files changed, 31 insertions(+), 13 deletions(-)

diff --git a/lib_com/stat_com.h b/lib_com/stat_com.h
index 78d358be5..45a16dc1a 100644
--- a/lib_com/stat_com.h
+++ b/lib_com/stat_com.h
@@ -411,7 +411,7 @@ typedef struct
     Word16 psize_norm[NPART];          /* Partition sizes, fractional variable Q15-psize_norm_exp*/
     Word16 psize_inv[NPART];           /* Inverse of partition sizes Q15*/
                                        // Word16 FFTscalingFactor;  /* Squared ratio between core signal analysis FFT and noise estimator FFT */
-    Word16 scalingFactor;              // Q15
+    Word16 scalingFactor;              // exp = -15
     Word16 invScalingFactor;           // Q15
     Word16 nCLDFBpart;                 /* Number of CLDFB spectral partitions */
     Word16 CLDFBpart[NPARTCLDFB];      /* CLDFB Partition upper boundaries (band indices starting from 0 above the core coder bands) */
diff --git a/lib_enc/fd_cng_enc.c b/lib_enc/fd_cng_enc.c
index 5c493876b..5fdc5e6f0 100644
--- a/lib_enc/fd_cng_enc.c
+++ b/lib_enc/fd_cng_enc.c
@@ -92,10 +92,12 @@ void perform_noise_estimation_enc_ivas_fx(
     move16();
     assert( numSlots == 16 );
 
-    Word32 numSlots_inv_fx = 134217728;
+    Word32 numSlots_inv_fx = 1073741824; // Q34 of .0625
     move32();
     Word32 *periodog = hFdCngEnc->hFdCngCom->periodog; /* exp(peridog_exp) */
     Word32 *ptr_per_fx = periodog;
+    Word64 periodog_64;
+    Word16 periodog_exp[PERIODOGLEN];
     Word16 npart = hFdCngEnc->hFdCngCom->npart; /* Q0 */
     move16();
     Word16 nFFTpart = hFdCngEnc->hFdCngCom->nFFTpart; /* Q0 */
@@ -130,19 +132,19 @@ void perform_noise_estimation_enc_ivas_fx(
         SWITCH( input_Fs )
         {
             case 8000:
-                scaleEB_fx = 62912;
+                scaleEB_fx = 251648; // Q35
                 move32();
                 BREAK;
             case 16000:
-                scaleEB_fx = 15728;
+                scaleEB_fx = 62912; // Q35
                 move32();
                 BREAK;
             case 32000:
-                scaleEB_fx = 3928;
+                scaleEB_fx = 15728; // Q35
                 move32();
                 BREAK;
             case 48000:
-                scaleEB_fx = 1744;
+                scaleEB_fx = 6991; // Q35
                 move32();
                 BREAK;
             default:
@@ -151,8 +153,8 @@ void perform_noise_estimation_enc_ivas_fx(
     }
     ELSE
     {
-        scaleEB_fx = Mpy_32_16_1( numSlots_inv_fx, hFdCngEnc->hFdCngCom->scalingFactor );
-        scaleEB_fx = L_shl( scaleEB_fx, 4 );
+        scaleEB_fx = Mpy_32_32( numSlots_inv_fx, L_deposit_l( hFdCngEnc->hFdCngCom->scalingFactor ) ); // Q34 + Q30 - Q31 = Q33
+        scaleEB_fx = L_shl( scaleEB_fx, 2 );                                                           // Q35
     }
 
     /* preemphasis compensation and grouping of per bin energies into msPeriodog */
@@ -167,22 +169,38 @@ void perform_noise_estimation_enc_ivas_fx(
     hFdCngEnc->msPeriodog_fx_exp_fft = add( band_energies_exp, PREEMPH_COMPENSATION_EXP );
     move16();
 
+    Word16 max_exp = -31;
+    move16();
+    i = 0;
+    move16();
     /* Adjust to the desired time resolution by averaging the periodograms over the time slots */
     FOR( j = numCoreBands; j < regularStopBand; j++ )
     {
-        *ptr_per_fx = Mpy_32_32( enerBuffer[j], scaleEB_fx ); /* exp(enerBuffer_exp) */
+        periodog_64 = W_mult_32_32( enerBuffer[j], scaleEB_fx );
+        Word16 scale = W_norm( periodog_64 );
+        *ptr_per_fx = W_extract_h( W_shl( periodog_64, scale ) );
         move32();
+        periodog_exp[i] = sub( Q31, add( add( sub( Q31, enerBuffer_exp ), 35 - 31 ), scale ) );
+        move16();
+        max_exp = s_max( max_exp, periodog_exp[i] );
 
         ptr_per_fx++;
-        move16();
+        i++;
     }
-
     /* exponent for cldfb part of msPeriodog */
-    hFdCngEnc->hFdCngCom->exp_cldfb_periodog = add( sub( enerBuffer_exp, 4 ), CLDFBscalingFactor_EXP );
-    move16();
+    // hFdCngEnc->hFdCngCom->exp_cldfb_periodog = add( sub( enerBuffer_exp, 4 ), CLDFBscalingFactor_EXP );
+    //  move16();
 
     numBands = sub( regularStopBand, numCoreBands ); /* Q0 */
+    FOR( i = 0; i < numBands; i++ )
+    {
+
+        periodog[i] = L_shr( periodog[i], sub( max_exp, periodog_exp[i] ) );
 
+        move16();
+    }
+    hFdCngEnc->hFdCngCom->exp_cldfb_periodog = max_exp;
+    move16();
     IF( numBands > 0 )
     {
         ///* Adjust CLDFB filterbank to the desired frequency resolution by averaging over spectral partitions for SID transmission */
-- 
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