[x265] [PATCH] rc: improve loop in clipQscale

[Ximing Cheng]

# HG changeset patch
# User Ximing Cheng <ximingcheng at tencent.com>
# Date 1446797063 -28800
#      Fri Nov 06 16:04:23 2015 +0800
# Node ID f11b17b4656a85a15dc82fd04485fbf920848e4d
# Parent  45ea73c63c12c66e5e5e777e80853c8b3cadf101
rc: improve loop in clipQscale

diff -r 45ea73c63c12 -r f11b17b4656a source/encoder/ratecontrol.cpp
--- a/source/encoder/ratecontrol.cpp	Fri Nov 06 11:55:27 2015 +0530
+++ b/source/encoder/ratecontrol.cpp	Fri Nov 06 16:04:23 2015 +0800
@@ -1756,6 +1756,7 @@
             * is in a reasonable state by the end of the lookahead. */
             int loopTerminate = 0;
             /* Avoid an infinite loop. */
+            double pSliceFactor = m_sliceType == I_SLICE ? m_param->rc.ipFactor : (m_sliceType == B_SLICE ? 1 / m_param->rc.pbFactor : 1);
             for (int iterations = 0; iterations < 1000 && loopTerminate != 3; iterations++)
             {
                 double frameQ[3];
@@ -1764,7 +1765,7 @@
                 double bufferFillCur = m_bufferFill - curBits;
                 double targetFill;
                 double totalDuration = m_frameDuration;
-                frameQ[P_SLICE] = m_sliceType == I_SLICE ? q * m_param->rc.ipFactor : (m_sliceType == B_SLICE ? q / m_param->rc.pbFactor : q);
+                frameQ[P_SLICE] = q * pSliceFactor;
                 frameQ[B_SLICE] = frameQ[P_SLICE] * m_param->rc.pbFactor;
                 frameQ[I_SLICE] = frameQ[P_SLICE] / m_param->rc.ipFactor;
                 /* Loop over the planned future frames. */
@@ -1798,12 +1799,15 @@
                     continue;
                 }
                 /* Try to get the buffer not more than 80% filled, but don't set an impossible goal. */
-                targetFill = x265_clip3(m_bufferSize * (1 - 0.2 * finalDur), m_bufferSize, m_bufferFill - totalDuration * m_vbvMaxRate * 0.5);
-                if (m_isCbr && bufferFillCur > targetFill && !m_isSceneTransition)
+                if (m_isCbr && !m_isSceneTransition)
                 {
-                    q /= 1.01;
-                    loopTerminate |= 2;
-                    continue;
+                    targetFill = x265_clip3(m_bufferSize * (1 - 0.2 * finalDur), m_bufferSize, m_bufferFill - totalDuration * m_vbvMaxRate * 0.5);
+                    if (bufferFillCur > targetFill)
+                    {
+                        q /= 1.01;
+                        loopTerminate |= 2;
+                        continue;
+                    }
                 }
                 break;
             }
@@ -1857,7 +1861,7 @@
         if (m_rateFactorMaxIncrement)
         {
             double qpNoVbv = x265_qScale2qp(q0);
-            double qmax = X265_MIN(MAX_MAX_QPSCALE,x265_qp2qScale(qpNoVbv + m_rateFactorMaxIncrement));
+            double qmax = X265_MIN(MAX_MAX_QPSCALE, x265_qp2qScale(qpNoVbv + m_rateFactorMaxIncrement));
             return x265_clip3(MIN_QPSCALE, qmax, q);
         }
     }