From 63b919d2426d0fbab0aba880a1220aed63fc5397 Mon Sep 17 00:00:00 2001
From: "Christian R. Helmrich" <c.helmrich@ecodis.de>
Date: Sat, 30 May 2020 18:00:00 +0200
Subject: [PATCH] check common_tns flag

---
 src/lib/bitStreamWriter.cpp | 21 +++++++++++++++++----
 src/lib/bitStreamWriter.h   |  2 +-
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/src/lib/bitStreamWriter.cpp b/src/lib/bitStreamWriter.cpp
index 3219cc0..ad08740 100644
--- a/src/lib/bitStreamWriter.cpp
+++ b/src/lib/bitStreamWriter.cpp
@@ -346,7 +346,7 @@ unsigned BitStreamWriter::writeFDChannelStream (const CoreCoderData& elData, Ent
 
 unsigned BitStreamWriter::writeStereoCoreToolInfo (const CoreCoderData& elData, EntropyCoder& entrCoder,
 #if !RESTRICT_TO_AAC
-                                                   const bool timeWarping,
+                                                   const bool timeWarping, bool* const commonTnsFlag,
 #endif
                                                    const bool indepFlag /*= false*/)
 {
@@ -466,14 +466,27 @@ unsigned BitStreamWriter::writeStereoCoreToolInfo (const CoreCoderData& elData,
 #endif
   if (elData.tnsActive)
   {
+    bool commonTns = elData.commonTnsData;
+
     if (elData.commonWindow)
     {
-      m_auBitStream.write (elData.commonTnsData ? 1 : 0, 1);
+#if !RESTRICT_TO_AAC
+      if ((commonTnsFlag != nullptr) && !commonTns)  // common_tns
+      {
+        const uint8_t* data1 = (uint8_t*) &tnsData0; // fast comp.
+        const uint8_t* data2 = (uint8_t*) &tnsData1; // portable??
+
+        commonTns = true;
+        for (b = 0; b < sizeof (TnsData); b++) commonTns &= (data1[b] == data2[b]);
+        *commonTnsFlag = commonTns;
+      }
+#endif
+      m_auBitStream.write (/*optim.*/commonTns ? 1 : 0, 1);
       bitCount++;
     }
     m_auBitStream.write (elData.tnsOnLeftRight ? 1 : 0, 1);
     bitCount++;
-    if (elData.commonTnsData)
+    if (commonTns)
     {
       bitCount += writeChannelWiseTnsData (tnsData0, icsInfo0.windowSequence == EIGHT_SHORT);
     }
@@ -641,7 +654,7 @@ unsigned BitStreamWriter::createAudioFrame (CoreCoderData** const elementData,
         bitCount += 2;
         bitCount += writeStereoCoreToolInfo (*elData, entropyCoder[ci], // L
 #if !RESTRICT_TO_AAC
-                                             tw_mdct[el],
+                                             tw_mdct[el], &elementData[el]->commonTnsData,
 #endif
                                              usacIndependencyFlag);
         bitCount += writeFDChannelStream (*elData, entropyCoder[ci], 0, // L
diff --git a/src/lib/bitStreamWriter.h b/src/lib/bitStreamWriter.h
index 2fc28de..25c0287 100644
--- a/src/lib/bitStreamWriter.h
+++ b/src/lib/bitStreamWriter.h
@@ -43,7 +43,7 @@ private:
                                     const bool indepFlag = false);
   unsigned writeStereoCoreToolInfo (const CoreCoderData& elData, EntropyCoder& entrCoder,
 #if !RESTRICT_TO_AAC
-                                    const bool timeWarping,
+                                    const bool timeWarping, bool* const commonTnsFlag,
 #endif
                                     const bool indepFlag = false);