[x265] [PATCH] rc: fixes inconsistent output in linux because of RC Lock in CQP/CRF

[aarthi at multicorewareinc.com]

# HG changeset patch
# User Aarthi Thirumalai
# Date 1435312791 -19800
#      Fri Jun 26 15:29:51 2015 +0530
# Node ID 2dac97717742d6187df7798bdfbd8a9f04e6f446
# Parent  f7bbb04e1992a238aee739a0e21777932c1dfa57
rc: fixes inconsistent output in linux because of RC Lock in CQP/CRF

the inconsistency is due to a race hazrd in slice context initializations when 2 Frame Encoders complete
RateControlStart in correct order but slice context initializations in the wrong order in CRF/CQP.

diff -r f7bbb04e1992 -r 2dac97717742 source/encoder/frameencoder.cpp
--- a/source/encoder/frameencoder.cpp	Fri Jun 26 10:16:29 2015 +0530
+++ b/source/encoder/frameencoder.cpp	Fri Jun 26 15:29:51 2015 +0530
@@ -474,6 +474,19 @@
         m_nalList.serialize(NAL_UNIT_PREFIX_SEI, m_bs);
     }
 
+    /* CQP and CRF (without capped VBV) doesn't use mid-frame statistics to 
+     * tune RateControl parameters for other frames.
+     * Hence, for these modes, update m_startEndOrder and unlock RC for previous threads waiting in
+     * RateControlEnd here, after the slicecontexts are initialized. For the rest - ABR
+     * and VBV, unlock only after rateControlUpdateStats of this frame is called */
+    if (m_param->rc.rateControlMode != X265_RC_ABR && !m_top->m_rateControl->m_isVbv)
+    {
+        m_top->m_rateControl->m_startEndOrder.incr();
+
+        if (m_rce.encodeOrder < m_param->frameNumThreads - 1)
+            m_top->m_rateControl->m_startEndOrder.incr(); // faked rateControlEnd calls for negative frames
+    }
+
     /* Analyze CTU rows, most of the hard work is done here.  Frame is
      * compressed in a wave-front pattern if WPP is enabled. Row based loop
      * filters runs behind the CTU compression and reconstruction */
diff -r f7bbb04e1992 -r 2dac97717742 source/encoder/ratecontrol.cpp
--- a/source/encoder/ratecontrol.cpp	Fri Jun 26 10:16:29 2015 +0530
+++ b/source/encoder/ratecontrol.cpp	Fri Jun 26 15:29:51 2015 +0530
@@ -1087,18 +1087,6 @@
     }
     m_framesDone++;
 
-    /* CQP and CRF (without capped VBV) doesn't use mid-frame statistics to 
-     * tune RateControl parameters for other frames.
-     * Hence, for these modes, update m_startEndOrder and unlock RC for previous threads waiting in
-     * RateControlEnd here.those modes here. For the rest - ABR
-     * and VBV, unlock only after rateControlUpdateStats of this frame is called */
-    if (m_param->rc.rateControlMode != X265_RC_ABR && !m_isVbv)
-    {
-        m_startEndOrder.incr();
-
-        if (rce->encodeOrder < m_param->frameNumThreads - 1)
-            m_startEndOrder.incr(); // faked rateControlEnd calls for negative frames
-    }
     return m_qp;
 }