From 2e17beffc4463d5de3ad112cf023ed511658d5b9 Mon Sep 17 00:00:00 2001
From: "Christian R. Helmrich" <c.helmrich@ecodis.de>
Date: Thu, 12 Mar 2020 02:00:00 +0100
Subject: [PATCH] low-rate tuning

---
 src/lib/exhaleEnc.cpp      |  2 +-
 src/lib/quantization.cpp   | 23 +++++++++++++++++++++--
 src/lib/specGapFilling.cpp |  2 +-
 3 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/src/lib/exhaleEnc.cpp b/src/lib/exhaleEnc.cpp
index e6b89b8..d4b75ef 100644
--- a/src/lib/exhaleEnc.cpp
+++ b/src/lib/exhaleEnc.cpp
@@ -535,7 +535,7 @@ unsigned ExhaleEncoder::psychBitAllocation () // perceptual bit-allocation via s
   const unsigned samplingRate    = toSamplingRate (m_frequencyIdx);
   const unsigned lfeChannelIndex = (m_channelConf >= CCI_6_CH ? __max (5, nChannels - 1) : USAC_MAX_NUM_CHANNELS);
   const uint32_t maxSfbLong      = (samplingRate < 37566 ? 51 /*32 kHz*/ : brModeAndFsToMaxSfbLong (m_bitRateMode, samplingRate));
-  const uint64_t scaleSr         = (samplingRate < 27713 ? 37 - m_bitRateMode : 38 - (m_bitRateMode > 2 ? 1 : 0));
+  const uint64_t scaleSr         = (samplingRate < 27713 ? 38 - m_bitRateMode : 38 - (m_bitRateMode > 2 ? 1 : 0));
   const uint64_t scaleBr         = (m_bitRateMode == 0 ? 32 : scaleSr - eightTimesSqrt256Minus[256 - m_bitRateMode] - ((m_bitRateMode - 1) >> 1));
   uint32_t* sfbStepSizes = (uint32_t*) m_tempIntBuf;
   uint8_t  meanSpecFlat[USAC_MAX_NUM_CHANNELS];
diff --git a/src/lib/quantization.cpp b/src/lib/quantization.cpp
index f28514c..33645a3 100644
--- a/src/lib/quantization.cpp
+++ b/src/lib/quantization.cpp
@@ -38,7 +38,7 @@ static inline short getBitCount (EntropyCoder& entrCoder, const int sfIndex, con
 #if EC_TRELLIS_OPT_CODING && !EC_TRAIN
 static inline double getLagrangeValue (const uint16_t rateIndex) // RD optimization constant
 {
-  return (108.0 + rateIndex * rateIndex) * 0.0009765625; // /1024
+  return (95.0 + rateIndex * rateIndex) * 0.0009765625; // / 1024
 }
 #endif
 
@@ -191,14 +191,33 @@ uint8_t SfbQuantizer::quantizeMagnSfb (const unsigned* const coeffMagn, const ui
 
         // re-compute least-squares optimal scale factor modifier
         if (dNum > SF_THRESH_POS * dDen) sf++;
+#if !SFB_QUANT_PERCEPT_OPT
         else
-        if (dNum < SF_THRESH_NEG * dDen) sf--;
+        if (dNum < SF_THRESH_NEG * dDen) sf--; // reduces SFB RMS
+#endif
       } // if nonzero
 
       if (sigMaxQ) *sigMaxQ = (numQ > 0 ? maxQ : 0); // a new max
       if (sigNumQ) *sigNumQ = numQ; // a new nonzero coeff. count
     }
   }
+#endif // EC_TRELLIS_OPT_CODING
+
+#if SFB_QUANT_PERCEPT_OPT
+  if ((numQ > 0) && (sf > 0 && sf <= scaleFactor)) // recover RMS
+  {
+    const double magnNormDiv = m_lutSfNorm[sf];
+
+    dNum = 0.0;  // dDen has normalized energy after quantization
+    for (int i = numCoeffs - 1; i >= 0; i--)
+    {
+      const double normalizedMagn = (double) coeffMagn[i] * magnNormDiv;
+
+      dNum += normalizedMagn * normalizedMagn; // TODO: use SIMD?
+    }
+
+    if (dNum > SF_THRESH_POS * SF_THRESH_POS * dDen) sf++;
+  }
 #endif
   return (uint8_t) __max (0, sf); // optimized scale factor index
 }
diff --git a/src/lib/specGapFilling.cpp b/src/lib/specGapFilling.cpp
index 72299d8..b501018 100644
--- a/src/lib/specGapFilling.cpp
+++ b/src/lib/specGapFilling.cpp
@@ -165,7 +165,7 @@ uint8_t SpecGapFiller::getSpecGapFillParams (const SfbQuantizer& sfbQuantizer, c
   }
   s = 0;
 #endif
-  u = __min (7, uint16_t (14.47118288 + 9.965784285 * log10 (magnSum / (double) u)));
+  u = __min (7 + (specFlat >> 5), uint16_t (14.47118288 + 9.965784285 * log10 (magnSum / (double) u)));
   u = __max (1, u - int (specFlat >> 5)); // SFM-adaptive reduction
 
   magnSum = pow (2.0, (14 - u) / 3.0); // noiseVal^-1, 23003-3, 7.2