SBR encoder improvement

SBR encoder: Introduce coupling energy ratio limitation to prevent undesirable SBR band
     amplification while decoding.

Bug 9428126

Change-Id: I18a77cd1a178fff7531b490779a29a0df7d993af

libAACenc/src/aacenc_lib.cpp

@@ -98,7 +98,7 @@ amm-info@iis.fraunhofer.de
 /* Encoder library info */
 #define AACENCODER_LIB_VL0 3
 #define AACENCODER_LIB_VL1 4
-#define AACENCODER_LIB_VL2 3
+#define AACENCODER_LIB_VL2 4
 #define AACENCODER_LIB_TITLE "AAC Encoder"
 #define AACENCODER_LIB_BUILD_DATE __DATE__
 #define AACENCODER_LIB_BUILD_TIME __TIME__

libSBRenc/src/env_est.cpp

@@ -817,22 +817,22 @@ calculateSbrEnvelope (FIXP_DBL **RESTRICT YBufferLeft,  /*! energy buffer left *
       }
 
       /* ld64 to integer conversion */
-      nrgLeft = fixMin(fixMax(nrgLeft,FL2FXCONST_DBL(0.0f)),FL2FXCONST_DBL(0.5f));
+      nrgLeft = fixMin(fixMax(nrgLeft,FL2FXCONST_DBL(0.0f)),(FL2FXCONST_DBL(0.5f)>>oneBitLess));
       nrgLeft = (FIXP_DBL)(LONG)nrgLeft >> (DFRACT_BITS-1-LD_DATA_SHIFT-1-oneBitLess-1);
       sfb_nrgLeft[m] = ((INT)nrgLeft+1)>>1; /* rounding */
 
       if (stereoMode == SBR_COUPLING) {
         FIXP_DBL scaleFract;
+        int sc0, sc1;
 
-        if (nrgRight != FL2FXCONST_DBL(0.0f)) {
-          int sc0 = CountLeadingBits(nrgLeft2);
-          int sc1 = CountLeadingBits(nrgRight);
+        nrgLeft2 = fixMax((FIXP_DBL)0x1, nrgLeft2);
+        nrgRight = fixMax((FIXP_DBL)0x1, nrgRight);
+
+        sc0 = CountLeadingBits(nrgLeft2);
+        sc1 = CountLeadingBits(nrgRight);
 
         scaleFract = ((FIXP_DBL)(sc0-sc1)) << (DFRACT_BITS-1-LD_DATA_SHIFT); /* scale value in ld64 representation */
         nrgRight = CalcLdData(nrgLeft2<<sc0) - CalcLdData(nrgRight<<sc1) - scaleFract;
-        }
-        else
-          nrgRight =  FL2FXCONST_DBL(0.5f);   /* ld64(4294967296.0f) */
 
         /* ld64 to integer conversion */
         nrgRight = (FIXP_DBL)(LONG)(nrgRight) >> (DFRACT_BITS-1-LD_DATA_SHIFT-1-oneBitLess);

libSBRenc/src/sbr_encoder.cpp

@@ -103,7 +103,7 @@ amm-info@iis.fraunhofer.de
 
 #define SBRENCODER_LIB_VL0 3
 #define SBRENCODER_LIB_VL1 3
-#define SBRENCODER_LIB_VL2 0
+#define SBRENCODER_LIB_VL2 1