[x265] [PATCH RFC] rc: define function for updating rate control statistics in processRowEncoder

[santhoshini at multicorewareinc.com]

# HG changeset patch
# User Santhoshini Sekar <santhoshini at multicorewareinc.com>
# Date 1405416189 -19800
#      Tue Jul 15 14:53:09 2014 +0530
# Node ID 8f7ef1fd08bd4e045921e8831b3c57b1ea866c4d
# Parent  e171ad8bc8a3611b75e084587f4c07c41427c73d
rc: define function for updating rate control statistics in processRowEncoder

Rate control updates its statistics like bits in RateControlEnd. With
frame parallelsim enabled and N parallel frames running, the feedback given to
rate control is delayed until rateControlStart of N frames are called. To avoid
this delay, update rate control statistics for every frame after encode of few
frames are done in processRowEncoder.By updating statistics for every frame we
make ABR to function more accurately(predicts more accurate QP) making use of
latest data rather than stale values.

diff -r e171ad8bc8a3 -r 8f7ef1fd08bd source/encoder/ratecontrol.cpp
--- a/source/encoder/ratecontrol.cpp	Fri Jul 11 01:44:43 2014 -0500
+++ b/source/encoder/ratecontrol.cpp	Tue Jul 15 14:53:09 2014 +0530
@@ -781,6 +781,32 @@
     }
 }
 
+void RateControl::rateControlUpdateStats(RateControlEntry* rce)
+{
+    if (rce->sliceType == I_SLICE)
+    {
+        /* previous I still had a residual; roll it into the new loan */
+        if (m_residualFrames)
+            rce->rowTotalBits += m_residualCost * m_residualFrames;
+
+        m_residualFrames = X265_MIN(s_amortizeFrames, m_param->keyframeMax);
+        m_residualCost = (int)((rce->rowTotalBits * s_amortizeFraction) / m_residualFrames);
+        rce->rowTotalBits -= m_residualCost * m_residualFrames;
+    }
+    else if (m_residualFrames)
+    {
+         rce->rowTotalBits += m_residualCost;
+    }
+
+    if (rce->sliceType != B_SLICE)
+        rce->rowCplxrSum =  rce->rowTotalBits * x265_qp2qScale(rce->qpaRc) / rce->qRceq;
+    else
+        rce->rowCplxrSum = rce->rowTotalBits * x265_qp2qScale(rce->qpaRc) / (rce->qRceq * fabs(m_param->rc.pbFactor));
+
+    m_cplxrSum += rce->rowCplxrSum;
+    m_totalBits += rce->rowTotalBits;
+}
+
 void RateControl::checkAndResetABR(RateControlEntry* rce, bool isFrameDone)
 {
     double abrBuffer = 2 * m_param->rc.rateTolerance * m_bitrate;
diff -r e171ad8bc8a3 -r 8f7ef1fd08bd source/encoder/ratecontrol.h
--- a/source/encoder/ratecontrol.h	Fri Jul 11 01:44:43 2014 -0500
+++ b/source/encoder/ratecontrol.h	Tue Jul 15 14:53:09 2014 +0530
@@ -68,6 +68,8 @@
     double frameSizePlanned;  /* frame Size decided by RateCotrol before encoding the frame */
     double bufferRate;
     double movingAvgSum;
+    double   rowCplxrSum;
+    int64_t  rowTotalBits;  /* update cplxrsum and totalbits at the end of 2 rows */
     double qpNoVbv;
     double bufferFill;
     Predictor rowPreds[3][2];
@@ -158,6 +160,7 @@
     // to be called for each frame to process RateControl and set QP
     void rateControlStart(Frame* pic, Lookahead *, RateControlEntry* rce, Encoder* enc);
     void calcAdaptiveQuantFrame(Frame *pic);
+    void rateControlUpdateStats(RateControlEntry* rce);
     int rateControlEnd(Frame* pic, int64_t bits, RateControlEntry* rce, FrameStats* stats);
     int rowDiagonalVbvRateControl(Frame* pic, uint32_t row, RateControlEntry* rce, double& qpVbv);
     void hrdFullness(SEIBufferingPeriod* sei);