[x265] [PATCH] rc: fix chroma qp and chroma lambda derivations

[aarthi at multicorewareinc.com]

# HG changeset patch
# User Aarthi Thirumalai
# Date 1417675781 -19800
#      Thu Dec 04 12:19:41 2014 +0530
# Node ID 23061220a5fe287cac893320d8ee0a782d6767c0
# Parent  511dde5ac1deee96a0105bb87e14670ef5ed72a6
rc: fix chroma qp and chroma lambda derivations.

fix the chroma qp values for Main10 profile, derive chroma qp from luma qp values
according to the HEVC spec.
improves quality at high qps.

diff -r 511dde5ac1de -r 23061220a5fe source/common/constants.cpp
--- a/source/common/constants.cpp	Thu Dec 04 12:43:06 2014 +0530
+++ b/source/common/constants.cpp	Thu Dec 04 12:19:41 2014 +0530
@@ -289,11 +289,21 @@
     {  4, -13, 22, -31, 38, -46, 54, -61, 67, -73, 78, -82, 85, -88, 90, -90, 90, -90, 88, -85, 82, -78, 73, -67, 61, -54, 46, -38, 31, -22, 13, -4 }
 };
 
+
+#if HIGH_BIT_DEPTH
+const uint8_t g_chromaScale[ChromaQPMappingTableSize] =
+{
+    0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,
+    51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51
+};
+
+#else
 const uint8_t g_chromaScale[ChromaQPMappingTableSize] =
 {
     0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 29, 30, 31, 32, 33, 33, 34, 34, 35, 35, 36, 36, 37, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,
     51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51
-};
+}; 
+#endif
 
 const uint8_t g_chroma422IntraAngleMappingTable[AngleMapping422TableSize] =
 { 0, 1, 2, 2, 2, 2, 3, 5, 7, 8, 10, 12, 13, 15, 17, 18, 19, 20, 21, 22, 23, 23, 24, 24, 25, 25, 26, 27, 27, 28, 28, 29, 29, 30, 31, DM_CHROMA_IDX };
diff -r 511dde5ac1de -r 23061220a5fe source/encoder/rdcost.h
--- a/source/encoder/rdcost.h	Thu Dec 04 12:43:06 2014 +0530
+++ b/source/encoder/rdcost.h	Thu Dec 04 12:19:41 2014 +0530
@@ -57,12 +57,12 @@
 
         setLambda(x265_lambda2_tab[qp], x265_lambda_tab[qp]);
 
-        int qpCb = Clip3(QP_MIN, QP_MAX_MAX, qp + slice.m_pps->chromaQpOffset[0]);
+        int qpCb = Clip3(QP_MIN, QP_MAX_MAX, (int)g_chromaScale[qp + slice.m_pps->chromaQpOffset[0]]);
         int chroma_offset_idx = X265_MIN(qp - qpCb + 12, MAX_CHROMA_LAMBDA_OFFSET);
         uint16_t lambdaOffset = m_psyRd ? x265_chroma_lambda2_offset_tab[chroma_offset_idx] : 256;
         setCbDistortionWeight(lambdaOffset);
 
-        int qpCr = Clip3(QP_MIN, QP_MAX_MAX, qp + slice.m_pps->chromaQpOffset[1]);
+        int qpCr = Clip3(QP_MIN, QP_MAX_MAX, (int)g_chromaScale[qp + slice.m_pps->chromaQpOffset[0]]);
         chroma_offset_idx = X265_MIN(qp - qpCr + 12, MAX_CHROMA_LAMBDA_OFFSET);
         lambdaOffset = m_psyRd ? x265_chroma_lambda2_offset_tab[chroma_offset_idx] : 256;
         setCrDistortionWeight(lambdaOffset);
diff -r 511dde5ac1de -r 23061220a5fe source/encoder/sao.cpp
--- a/source/encoder/sao.cpp	Thu Dec 04 12:43:06 2014 +0530
+++ b/source/encoder/sao.cpp	Thu Dec 04 12:19:41 2014 +0530
@@ -177,7 +177,7 @@
 {
     Slice* slice = frame->m_encData->m_slice;
 
-    int qpCb = Clip3(0, QP_MAX_MAX, qp + slice->m_pps->chromaQpOffset[0]);
+    int qpCb = Clip3(QP_MIN, QP_MAX_MAX, (int)g_chromaScale[qp + slice->m_pps->chromaQpOffset[0]]);
     m_lumaLambda = x265_lambda2_tab[qp];
     m_chromaLambda = x265_lambda2_tab[qpCb]; // Use Cb QP for SAO chroma
     m_frame = frame;