diff --git a/codec/decoder/core/inc/decoder.h b/codec/decoder/core/inc/decoder.h
index 4efef7d3..50f91c17 100644
--- a/codec/decoder/core/inc/decoder.h
+++ b/codec/decoder/core/inc/decoder.h
@@ -54,11 +54,6 @@ extern "C" {
  */
 int32_t DecoderConfigParam (PWelsDecoderContext pCtx, const SDecodingParam* kpParam);
 
-/*!
- * \brief   fill in default values of decoder context
- */
-void WelsDecoderDefaults (PWelsDecoderContext pCtx, SLogContext* pLogCtx);
-
 /*!
  *************************************************************************************
  * \brief   Initialize Wels decoder parameters and memory
@@ -73,7 +68,7 @@ void WelsDecoderDefaults (PWelsDecoderContext pCtx, SLogContext* pLogCtx);
  * \note    N/A
  *************************************************************************************
  */
-int32_t WelsInitDecoder (PWelsDecoderContext pCtx, SLogContext* pLogCtx);
+int32_t WelsInitDecoder (PWelsDecoderContext pCtx, const bool bParseOnly, SLogContext* pLogCtx);
 
 /*!
  *************************************************************************************
@@ -115,9 +110,9 @@ int32_t WelsRequestMem (PWelsDecoderContext pCtx, const int32_t kiMbWidth, const
 
 
 /*
- *  free memory dynamically allocated during decoder
+ *  free memory blocks in avc
  */
-  void WelsFreeDynamicMemory (PWelsDecoderContext pCtx);
+void WelsFreeMem (PWelsDecoderContext pCtx);
 
 /*
  * set colorspace format in decoder
@@ -135,19 +130,7 @@ int32_t DecoderSetCsp (PWelsDecoderContext pCtx, const int32_t kiColorFormat);
  */
 int32_t SyncPictureResolutionExt (PWelsDecoderContext pCtx, const int32_t kiMbWidth, const int32_t kiMbHeight);
 
-/*!
- * \brief   init decoder predictive function pointers including ASM functions during MB reconstruction
- * \param   pCtx        Wels decoder context
- * \param   uiCpuFlag   cpu assembly indication
- */
-void InitPredFunc (PWelsDecoderContext pCtx, uint32_t uiCpuFlag);
-
-/*!
- * \brief   init decoder internal function pointers including ASM functions
- * \param   pCtx        Wels decoder context
- * \param   uiCpuFlag   cpu assembly indication
- */
-void InitDecFuncs (PWelsDecoderContext pCtx, uint32_t uiCpuFlag);
+void AssignFuncPointerForRec (PWelsDecoderContext pCtx);
 
 void GetVclNalTemporalId (PWelsDecoderContext pCtx); //get the info that whether or not have VCL NAL in current AU,
 //and if YES, get the temporal ID
diff --git a/codec/decoder/core/inc/decoder_context.h b/codec/decoder/core/inc/decoder_context.h
index 958627f1..8ffb473a 100644
--- a/codec/decoder/core/inc/decoder_context.h
+++ b/codec/decoder/core/inc/decoder_context.h
@@ -376,6 +376,7 @@ typedef struct TagWelsDecoderContext {
   ERROR_CON_IDC eErrorConMethod; //
 
 //for Parse only
+  bool bParseOnly;
   bool bFramePending;
   bool bFrameFinish;
   int32_t iNalNum;
diff --git a/codec/decoder/core/inc/decoder_core.h b/codec/decoder/core/inc/decoder_core.h
index 92e95576..61d96400 100644
--- a/codec/decoder/core/inc/decoder_core.h
+++ b/codec/decoder/core/inc/decoder_core.h
@@ -72,21 +72,21 @@ int32_t ExpandBsBuffer (PWelsDecoderContext pCtx, const int32_t kiSrcLen);
 int32_t CheckBsBuffer (PWelsDecoderContext pCtx, const int32_t kiSrcLen);
 
 /*
- * WelsInitStaticMemory
- * Memory request for introduced data at decoder start
+ * WelsInitMemory
+ * Memory request for introduced data
  * Especially for:
  * rbsp_au_buffer, cur_dq_layer_ptr and ref_dq_layer_ptr in MB info cache.
  * return:
  *  0 - success; otherwise returned error_no defined in error_no.h.
  */
-int32_t WelsInitStaticMemory (PWelsDecoderContext pCtx);
+int32_t WelsInitMemory (PWelsDecoderContext pCtx);
 
 /*
- * WelsFreeStaticMemory
- * Free memory introduced in WelsInitStaticMemory at destruction of decoder.
+ * WelsFreeMemory
+ * Free memory introduced in WelsInitMemory at destruction of decoder.
  *
  */
-void WelsFreeStaticMemory (PWelsDecoderContext pCtx);
+void WelsFreeMemory (PWelsDecoderContext pCtx);
 
 /*!
  * \brief   request memory when maximal picture width and height are available
diff --git a/codec/decoder/core/src/au_parser.cpp b/codec/decoder/core/src/au_parser.cpp
index de415457..fe8634f0 100644
--- a/codec/decoder/core/src/au_parser.cpp
+++ b/codec/decoder/core/src/au_parser.cpp
@@ -317,7 +317,7 @@ uint8_t* ParseNalHeader (PWelsDecoderContext pCtx, SNalUnitHeader* pNalUnitHeade
       iNalSize        -= NAL_UNIT_HEADER_EXT_SIZE;
       *pConsumedBytes += NAL_UNIT_HEADER_EXT_SIZE;
 
-      if (pCtx->pParam->bParseOnly) {
+      if (pCtx->bParseOnly) {
         pCurNal->sNalData.sVclNal.pNalPos = pSavedData->pCurPos;
         int32_t iTrailingZeroByte = 0;
         while (pSrcNal[iSrcNalLen - iTrailingZeroByte - 1] == 0x0) //remove final trailing 0 bytes
@@ -346,7 +346,7 @@ uint8_t* ParseNalHeader (PWelsDecoderContext pCtx, SNalUnitHeader* pNalUnitHeade
         pSavedData->pCurPos += iActualLen - iOffset;
       }
     } else {
-      if (pCtx->pParam->bParseOnly) {
+      if (pCtx->bParseOnly) {
         pCurNal->sNalData.sVclNal.pNalPos = pSavedData->pCurPos;
         int32_t iTrailingZeroByte = 0;
         while (pSrcNal[iSrcNalLen - iTrailingZeroByte - 1] == 0x0) //remove final trailing 0 bytes
@@ -1113,7 +1113,7 @@ int32_t ParseSps (PWelsDecoderContext pCtx, PBitStringAux pBsAux, int32_t* pPicW
   WELS_READ_VERIFY (BsGetOneBit (pBs, &uiCode)); //vui_parameters_present_flag
   pSps->bVuiParamPresentFlag = !!uiCode;
 
-  if (pCtx->pParam->bParseOnly) {
+  if (pCtx->bParseOnly) {
     if (kSrcNalLen >= SPS_PPS_BS_SIZE - 4) { //sps bs exceeds!
       pCtx->iErrorCode |= dsOutOfMemory;
       return GENERATE_ERROR_NO (ERR_LEVEL_PARAM_SETS, ERR_INFO_OUT_OF_MEMORY);
@@ -1416,7 +1416,7 @@ int32_t ParsePps (PWelsDecoderContext pCtx, PPps pPpsList, PBitStringAux pBsAux,
     memcpy (&pCtx->sPpsBuffer[uiPpsId], pPps, sizeof (SPps));
     pCtx->bPpsAvailFlags[uiPpsId] = true;
   }
-  if (pCtx->pParam->bParseOnly) {
+  if (pCtx->bParseOnly) {
     if (kSrcNalLen >= SPS_PPS_BS_SIZE - 4) { //pps bs exceeds
       pCtx->iErrorCode |= dsOutOfMemory;
       return GENERATE_ERROR_NO (ERR_LEVEL_PARAM_SETS, ERR_INFO_OUT_OF_MEMORY);
diff --git a/codec/decoder/core/src/decode_slice.cpp b/codec/decoder/core/src/decode_slice.cpp
index bec44c69..a0b0b485 100644
--- a/codec/decoder/core/src/decode_slice.cpp
+++ b/codec/decoder/core/src/decode_slice.cpp
@@ -90,7 +90,7 @@ int32_t WelsTargetSliceConstruction (PWelsDecoderContext pCtx) {
       break;
     }
 
-    if (!pCtx->pParam->bParseOnly) { //for parse only, actual recon MB unnecessary
+    if (!pCtx->bParseOnly) { //for parse only, actual recon MB unnecessary
       if (WelsTargetMbConstruction (pCtx)) {
         WelsLog (& (pCtx->sLogCtx), WELS_LOG_WARNING,
                  "WelsTargetSliceConstruction():::MB(%d, %d) construction error. pCurSlice_type:%d",
@@ -134,7 +134,7 @@ int32_t WelsTargetSliceConstruction (PWelsDecoderContext pCtx) {
   if ((pCurSlice->eSliceType != I_SLICE) && (pCurSlice->eSliceType != P_SLICE))
     return 0;
 
-  if (pCtx->pParam->bParseOnly) //for parse only, deblocking should not go on
+  if (pCtx->bParseOnly) //for parse only, deblocking should not go on
     return 0;
 
   pDeblockMb = WelsDeblockingMb;
diff --git a/codec/decoder/core/src/decoder.cpp b/codec/decoder/core/src/decoder.cpp
index 7e121928..f5291e16 100644
--- a/codec/decoder/core/src/decoder.cpp
+++ b/codec/decoder/core/src/decoder.cpp
@@ -272,13 +272,14 @@ void DestroyPicBuff (PPicBuff* ppPicBuf, CMemoryAlign* pMa) {
   pPicBuf = NULL;
   *ppPicBuf = NULL;
 }
-
 /*
  * fill data fields in default for decoder context
  */
-void WelsDecoderDefaults (PWelsDecoderContext pCtx, SLogContext* pLogCtx) {
+void WelsDecoderDefaults (PWelsDecoderContext pCtx, SLogContext* pLogCtx, CMemoryAlign* pMa) {
   int32_t iCpuCores               = 1;
+  memset (pCtx, 0, sizeof (SWelsDecoderContext));       // fill zero first
   pCtx->sLogCtx = *pLogCtx;
+  pCtx->pMemAlign = pMa;
 
   pCtx->pArgDec                   = NULL;
 
@@ -441,20 +442,18 @@ int32_t WelsRequestMem (PWelsDecoderContext pCtx, const int32_t kiMbWidth, const
 }
 
 /*
- *  free memory dynamically allocated during decoder
+ *  free memory blocks in avc
  */
-void WelsFreeDynamicMemory (PWelsDecoderContext pCtx) {
+void WelsFreeMem (PWelsDecoderContext pCtx) {
   int32_t iListIdx = 0;
   CMemoryAlign* pMa = pCtx->pMemAlign;
 
-  //free dq layer memory
-  UninitialDqLayersContext (pCtx);
-
-  //free FMO memory
+  /* TODO: free memory blocks introduced in avc */
   ResetFmoList (pCtx);
 
-  //free ref-pic list & picture memory
   WelsResetRefPic (pCtx);
+
+  // for sPicBuff
   for (iListIdx = LIST_0; iListIdx < LIST_A; ++ iListIdx) {
     PPicBuff* pPicBuff = &pCtx->pPicBuff[iListIdx];
     if (NULL != pPicBuff && NULL != *pPicBuff) {
@@ -469,8 +468,6 @@ void WelsFreeDynamicMemory (PWelsDecoderContext pCtx) {
   pCtx->iLastImgHeightInPixel = 0;
   pCtx->bFreezeOutput = true;
   pCtx->bHaveGotMemory = false;
-
-  //free CABAC memory
   pMa->WelsFree (pCtx->pCabacDecEngine, "pCtx->pCabacDecEngine");
 }
 
@@ -478,15 +475,19 @@ void WelsFreeDynamicMemory (PWelsDecoderContext pCtx) {
  * \brief   Open decoder
  */
 int32_t WelsOpenDecoder (PWelsDecoderContext pCtx) {
-  int iRet = ERR_NONE;
   // function pointers
-  InitDecFuncs (pCtx, pCtx->uiCpuFlag);
+  //initial MC function pointer--
+  int iRet = ERR_NONE;
+  InitMcFunc (& (pCtx->sMcFunc), pCtx->uiCpuFlag);
+
+  InitExpandPictureFunc (& (pCtx->sExpandPicFunc), pCtx->uiCpuFlag);
+  AssignFuncPointerForRec (pCtx);
 
   // vlc tables
   InitVlcTable (&pCtx->sVlcTable);
 
-  // static memory
-  iRet = WelsInitStaticMemory (pCtx);
+  // startup memory
+  iRet = WelsInitMemory (pCtx);
   if (ERR_NONE != iRet)
     return iRet;
 
@@ -506,9 +507,11 @@ int32_t WelsOpenDecoder (PWelsDecoderContext pCtx) {
  * \brief   Close decoder
  */
 void WelsCloseDecoder (PWelsDecoderContext pCtx) {
-  WelsFreeDynamicMemory (pCtx);
+  WelsFreeMem (pCtx);
 
-  WelsFreeStaticMemory (pCtx);
+  WelsFreeMemory (pCtx);
+
+  UninitialDqLayersContext (pCtx);
 
 #ifdef LONG_TERM_REF
   pCtx->bParamSetsLostFlag       = false;
@@ -528,7 +531,7 @@ int32_t DecoderConfigParam (PWelsDecoderContext pCtx, const SDecodingParam* kpPa
 
   memcpy (pCtx->pParam, kpParam, sizeof (SDecodingParam));
   pCtx->eOutputColorFormat = pCtx->pParam->eOutputColorFormat;
-  if (!pCtx->pParam->bParseOnly) {
+  if (!pCtx->bParseOnly) {
     int32_t iRet = DecoderSetCsp (pCtx, pCtx->pParam->eOutputColorFormat);
     if (iRet)
       return iRet;
@@ -543,7 +546,7 @@ int32_t DecoderConfigParam (PWelsDecoderContext pCtx, const SDecodingParam* kpPa
   }
   pCtx->eErrorConMethod = pCtx->pParam->eEcActiveIdc;
 
-  if (pCtx->pParam->bParseOnly) //parse only, disable EC method
+  if (pCtx->bParseOnly) //parse only, disable EC method
     pCtx->eErrorConMethod = ERROR_CON_DISABLE;
   InitErrorCon (pCtx);
 
@@ -571,11 +574,15 @@ int32_t DecoderConfigParam (PWelsDecoderContext pCtx, const SDecodingParam* kpPa
  * \note    N/A
  *************************************************************************************
  */
-int32_t WelsInitDecoder (PWelsDecoderContext pCtx, SLogContext* pLogCtx) {
+int32_t WelsInitDecoder (PWelsDecoderContext pCtx, const bool bParseOnly, SLogContext* pLogCtx) {
   if (pCtx == NULL) {
     return ERR_INFO_INVALID_PTR;
   }
 
+  // default
+  WelsDecoderDefaults (pCtx, pLogCtx, pCtx->pMemAlign);
+
+  pCtx->bParseOnly = bParseOnly;
   // open decoder
   return WelsOpenDecoder (pCtx);
 }
@@ -652,7 +659,7 @@ int32_t WelsDecodeBs (PWelsDecoderContext pCtx, const uint8_t* kpBsBuf, const in
       pRawData->pCurPos = pRawData->pHead;
     }
 
-    if (pCtx->pParam->bParseOnly) {
+    if (pCtx->bParseOnly) {
       pSavedData = &pCtx->sSavedData;
       if ((kiBsLen + 4) > (pSavedData->pEnd - pSavedData->pCurPos)) {
         pSavedData->pCurPos = pSavedData->pHead;
@@ -857,15 +864,7 @@ int32_t SyncPictureResolutionExt (PWelsDecoderContext pCtx, const int32_t kiMbWi
   return iErr;
 }
 
-void InitDecFuncs (PWelsDecoderContext pCtx, uint32_t uiCpuFlag) {
-  WelsBlockFuncInit (&pCtx->sBlockFunc, uiCpuFlag);
-  InitPredFunc (pCtx, uiCpuFlag);
-  InitMcFunc (& (pCtx->sMcFunc), uiCpuFlag);
-  InitExpandPictureFunc (& (pCtx->sExpandPicFunc), uiCpuFlag);
-  DeblockingInit (&pCtx->sDeblockingFunc, uiCpuFlag);
-}
-
-void InitPredFunc (PWelsDecoderContext pCtx, uint32_t uiCpuFlag) {
+void AssignFuncPointerForRec (PWelsDecoderContext pCtx) {
   pCtx->pGetI16x16LumaPredFunc[I16_PRED_V     ] = WelsI16x16LumaPredV_c;
   pCtx->pGetI16x16LumaPredFunc[I16_PRED_H     ] = WelsI16x16LumaPredH_c;
   pCtx->pGetI16x16LumaPredFunc[I16_PRED_DC    ] = WelsI16x16LumaPredDc_c;
@@ -917,7 +916,7 @@ void InitPredFunc (PWelsDecoderContext pCtx, uint32_t uiCpuFlag) {
   pCtx->pIdctResAddPredFunc8x8  = IdctResAddPred8x8_c;
 
 #if defined(HAVE_NEON)
-  if (uiCpuFlag & WELS_CPU_NEON) {
+  if (pCtx->uiCpuFlag & WELS_CPU_NEON) {
     pCtx->pIdctResAddPredFunc   = IdctResAddPred_neon;
 
     pCtx->pGetI16x16LumaPredFunc[I16_PRED_DC] = WelsDecoderI16x16LumaPredDc_neon;
@@ -942,7 +941,7 @@ void InitPredFunc (PWelsDecoderContext pCtx, uint32_t uiCpuFlag) {
 #endif//HAVE_NEON
 
 #if defined(HAVE_NEON_AARCH64)
-  if (uiCpuFlag & WELS_CPU_NEON) {
+  if (pCtx->uiCpuFlag & WELS_CPU_NEON) {
     pCtx->pIdctResAddPredFunc   = IdctResAddPred_AArch64_neon;
 
     pCtx->pGetI16x16LumaPredFunc[I16_PRED_DC] = WelsDecoderI16x16LumaPredDc_AArch64_neon;
@@ -972,7 +971,7 @@ void InitPredFunc (PWelsDecoderContext pCtx, uint32_t uiCpuFlag) {
 #endif//HAVE_NEON_AARCH64
 
 #if defined(X86_ASM)
-  if (uiCpuFlag & WELS_CPU_MMXEXT) {
+  if (pCtx->uiCpuFlag & WELS_CPU_MMXEXT) {
     pCtx->pIdctResAddPredFunc   = IdctResAddPred_mmx;
 
     ///////mmx code opt---
@@ -987,7 +986,7 @@ void InitPredFunc (PWelsDecoderContext pCtx, uint32_t uiCpuFlag) {
     pCtx->pGetI4x4LumaPredFunc[I4_PRED_DDL]  = WelsDecoderI4x4LumaPredDDL_mmx;
     pCtx->pGetI4x4LumaPredFunc[I4_PRED_VL ]  = WelsDecoderI4x4LumaPredVL_mmx;
   }
-  if (uiCpuFlag & WELS_CPU_SSE2) {
+  if (pCtx->uiCpuFlag & WELS_CPU_SSE2) {
     /////////sse2 code opt---
     pCtx->pGetI16x16LumaPredFunc[I16_PRED_DC] = WelsDecoderI16x16LumaPredDc_sse2;
     pCtx->pGetI16x16LumaPredFunc[I16_PRED_P]  = WelsDecoderI16x16LumaPredPlane_sse2;
@@ -1001,6 +1000,9 @@ void InitPredFunc (PWelsDecoderContext pCtx, uint32_t uiCpuFlag) {
     pCtx->pGetI4x4LumaPredFunc[I4_PRED_H]     = WelsDecoderI4x4LumaPredH_sse2;
   }
 #endif
+  DeblockingInit (&pCtx->sDeblockingFunc, pCtx->uiCpuFlag);
+
+  WelsBlockFuncInit (&pCtx->sBlockFunc, pCtx->uiCpuFlag);
 }
 
 //reset decoder number related statistics info
diff --git a/codec/decoder/core/src/decoder_core.cpp b/codec/decoder/core/src/decoder_core.cpp
index 63bc75f6..03e8ce06 100644
--- a/codec/decoder/core/src/decoder_core.cpp
+++ b/codec/decoder/core/src/decoder_core.cpp
@@ -72,7 +72,7 @@ static inline int32_t DecodeFrameConstruction (PWelsDecoderContext pCtx, uint8_t
     }
   }
 
-  if (pCtx->pParam->bParseOnly) { //should exit for parse only to prevent access NULL pDstInfo
+  if (pCtx->bParseOnly) { //should exit for parse only to prevent access NULL pDstInfo
     PAccessUnit pCurAu = pCtx->pAccessUnitList;
     if (dsErrorFree == pCtx->iErrorCode) { //correct decoding, add to data buffer
       SParserBsInfo* pParser = pCtx->pParserBsInfo;
@@ -467,7 +467,7 @@ int32_t InitBsBuffer (PWelsDecoderContext pCtx) {
   }
   pCtx->sRawData.pStartPos = pCtx->sRawData.pCurPos = pCtx->sRawData.pHead;
   pCtx->sRawData.pEnd = pCtx->sRawData.pHead + pCtx->iMaxBsBufferSizeInByte;
-  if (pCtx->pParam->bParseOnly) {
+  if (pCtx->bParseOnly) {
     pCtx->pParserBsInfo = static_cast<SParserBsInfo*> (pMa->WelsMallocz (sizeof (SParserBsInfo), "pCtx->pParserBsInfo"));
     if (pCtx->pParserBsInfo == NULL) {
       return ERR_INFO_OUT_OF_MEMORY;
@@ -538,14 +538,14 @@ int32_t CheckBsBuffer (PWelsDecoderContext pCtx, const int32_t kiSrcLen) {
 }
 
 /*
- * WelsInitStaticMemory
+ * WelsInitMemory
  * Memory request for new introduced data
  * Especially for:
  * rbsp_au_buffer, cur_dq_layer_ptr and ref_dq_layer_ptr in MB info cache.
  * return:
  *  0 - success; otherwise returned error_no defined in error_no.h.
 */
-int32_t WelsInitStaticMemory (PWelsDecoderContext pCtx) {
+int32_t WelsInitMemory (PWelsDecoderContext pCtx) {
   if (pCtx == NULL) {
     return ERR_INFO_INVALID_PTR;
   }
@@ -563,16 +563,22 @@ int32_t WelsInitStaticMemory (PWelsDecoderContext pCtx) {
 }
 
 /*
- * WelsFreeStaticMemory
- * Free memory introduced in WelsInitStaticMemory at destruction of decoder.
+ * WelsFreeMemory
+ * Free memory introduced in WelsInitMemory at destruction of decoder.
  *
  */
-void WelsFreeStaticMemory (PWelsDecoderContext pCtx) {
+void WelsFreeMemory (PWelsDecoderContext pCtx) {
   if (pCtx == NULL)
     return;
 
   CMemoryAlign* pMa = pCtx->pMemAlign;
 
+  if (NULL != pCtx->pParam) {
+    pMa->WelsFree (pCtx->pParam, "pCtx->pParam");
+
+    pCtx->pParam = NULL;
+  }
+
   MemFreeNalList (&pCtx->pAccessUnitList, pMa);
 
   if (pCtx->sRawData.pHead) {
@@ -582,7 +588,7 @@ void WelsFreeStaticMemory (PWelsDecoderContext pCtx) {
   pCtx->sRawData.pEnd                 = NULL;
   pCtx->sRawData.pStartPos            = NULL;
   pCtx->sRawData.pCurPos              = NULL;
-  if (pCtx->pParam->bParseOnly) {
+  if (pCtx->bParseOnly) {
     if (pCtx->sSavedData.pHead) {
       pMa->WelsFree (pCtx->sSavedData.pHead, "pCtx->sSavedData->pHead");
     }
@@ -599,12 +605,6 @@ void WelsFreeStaticMemory (PWelsDecoderContext pCtx) {
       pCtx->pParserBsInfo = NULL;
     }
   }
-
-  if (NULL != pCtx->pParam) {
-    pMa->WelsFree (pCtx->pParam, "pCtx->pParam");
-
-    pCtx->pParam = NULL;
-  }
 }
 /*
  *  DecodeNalHeaderExt
@@ -723,9 +723,8 @@ int32_t ParseSliceHeaderSyntaxs (PWelsDecoderContext pCtx, PBitStringAux pBs, co
   pSliceHead->eSliceType = static_cast <EWelsSliceType> (uiSliceType);
 
   WELS_READ_VERIFY (BsGetUe (pBs, &uiCode)); //pic_parameter_set_id
-  WELS_CHECK_SE_UPPER_ERROR (uiCode, (MAX_PPS_COUNT - 1), "iPpsId out of range",
-                             GENERATE_ERROR_NO (ERR_LEVEL_SLICE_HEADER,
-                                 ERR_INFO_PPS_ID_OVERFLOW));
+  WELS_CHECK_SE_UPPER_ERROR (uiCode, (MAX_PPS_COUNT - 1), "iPpsId out of range", GENERATE_ERROR_NO (ERR_LEVEL_SLICE_HEADER,
+                             ERR_INFO_PPS_ID_OVERFLOW));
   iPpsId = uiCode;
 
   //add check PPS available here
@@ -1975,7 +1974,7 @@ int32_t ConstructAccessUnit (PWelsDecoderContext pCtx, uint8_t** ppDst, SBufferI
 
   if (ERR_NONE != iErr) {
     ForceResetCurrentAccessUnit (pCtx->pAccessUnitList);
-    if (!pCtx->pParam->bParseOnly)
+    if (!pCtx->bParseOnly)
       pDstInfo->iBufferStatus = 0;
     pCtx->bNewSeqBegin = pCtx->bNewSeqBegin || pCtx->bNextNewSeqBegin;
     pCtx->bNextNewSeqBegin = false; // reset it
@@ -2340,7 +2339,7 @@ int32_t DecodeCurrentAccessUnit (PWelsDecoderContext pCtx, uint8_t** ppDst, SBuf
 
     if (dq_cur->uiLayerDqId == kuiTargetLayerDqId) {
       if (!pCtx->bInstantDecFlag) {
-        if (!pCtx->pParam->bParseOnly) {
+        if (!pCtx->bParseOnly) {
           //Do error concealment here
           if ((NeedErrorCon (pCtx)) && (pCtx->eErrorConMethod != ERROR_CON_DISABLE)) {
             ImplementErrorCon (pCtx);
@@ -2366,7 +2365,7 @@ int32_t DecodeCurrentAccessUnit (PWelsDecoderContext pCtx, uint8_t** ppDst, SBuf
             return iRet;
           }
         }
-        if (!pCtx->pParam->bParseOnly)
+        if (!pCtx->bParseOnly)
           ExpandReferencingPicture (pCtx->pDec->pData, pCtx->pDec->iWidthInPixel, pCtx->pDec->iHeightInPixel,
                                     pCtx->pDec->iLinesize,
                                     pCtx->sExpandPicFunc.pfExpandLumaPicture, pCtx->sExpandPicFunc.pfExpandChromaPicture);
@@ -2422,7 +2421,7 @@ bool CheckAndFinishLastPic (PWelsDecoderContext pCtx, uint8_t** ppDst, SBufferIn
       if (pCtx->sLastNalHdrExt.sNalUnitHeader.uiNalRefIdc > 0) {
         MarkECFrameAsRef (pCtx);
       }
-    } else if (pCtx->pParam->bParseOnly) { //clear parse only internal data status
+    } else if (pCtx->bParseOnly) { //clear parse only internal data status
       pCtx->pParserBsInfo->iNalNum = 0;
       pCtx->bFrameFinish = true; //clear frame pending status here!
     } else {
diff --git a/codec/decoder/core/src/pic_queue.cpp b/codec/decoder/core/src/pic_queue.cpp
index d1da2f1d..2383fbd6 100644
--- a/codec/decoder/core/src/pic_queue.cpp
+++ b/codec/decoder/core/src/pic_queue.cpp
@@ -83,7 +83,7 @@ PPicture AllocPicture (PWelsDecoderContext pCtx, const int32_t kiPicWidth, const
   iLumaSize     = iPicWidth * iPicHeight;
   iChromaSize   = iPicChromaWidth * iPicChromaHeight;
 
-  if (pCtx->pParam->bParseOnly) {
+  if (pCtx->bParseOnly) {
     pPic->pBuffer[0] = pPic->pBuffer[1] = pPic->pBuffer[2] = NULL;
     pPic->pData[0] = pPic->pData[1] = pPic->pData[2] = NULL;
     pPic->iLinesize[0] = iPicWidth;
diff --git a/codec/decoder/plus/src/welsDecoderExt.cpp b/codec/decoder/plus/src/welsDecoderExt.cpp
index a6fd6ad8..8c23bb74 100644
--- a/codec/decoder/plus/src/welsDecoderExt.cpp
+++ b/codec/decoder/plus/src/welsDecoderExt.cpp
@@ -243,7 +243,6 @@ int32_t CWelsDecoder::InitDecoder (const SDecodingParam* pParam) {
            "CWelsDecoder::init_decoder(), openh264 codec version = %s, ParseOnly = %d",
            VERSION_NUMBER, (int32_t)pParam->bParseOnly);
 
-  //reset decoder context
   if (m_pDecContext) //free
     UninitDecoder();
   m_pDecContext = (PWelsDecoderContext)WelsMallocz (sizeof (SWelsDecoderContext), "m_pDecContext");
@@ -253,8 +252,8 @@ int32_t CWelsDecoder::InitDecoder (const SDecodingParam* pParam) {
   m_pDecContext->pMemAlign = new CMemoryAlign (iCacheLineSize);
   WELS_VERIFY_RETURN_PROC_IF (1, (NULL == m_pDecContext->pMemAlign), UninitDecoder())
 
-  //fill in default value into context
-  WelsDecoderDefaults (m_pDecContext, &m_pWelsTrace->m_sLogCtx);
+  WELS_VERIFY_RETURN_PROC_IF (cmInitParaError, WelsInitDecoder (m_pDecContext, pParam->bParseOnly,
+                              &m_pWelsTrace->m_sLogCtx), UninitDecoder())
 
   //check param and update decoder context
   m_pDecContext->pParam = (SDecodingParam*) m_pDecContext->pMemAlign->WelsMallocz (sizeof (SDecodingParam),
@@ -263,9 +262,6 @@ int32_t CWelsDecoder::InitDecoder (const SDecodingParam* pParam) {
   int32_t iRet = DecoderConfigParam (m_pDecContext, pParam);
   WELS_VERIFY_RETURN_IFNEQ (iRet, cmResultSuccess);
 
-  //init decoder
-  WELS_VERIFY_RETURN_PROC_IF (cmInitParaError, WelsInitDecoder (m_pDecContext, &m_pWelsTrace->m_sLogCtx), UninitDecoder())
-
   return cmResultSuccess;
 }
 
@@ -295,7 +291,7 @@ long CWelsDecoder::SetOption (DECODER_OPTION eOptID, void* pOption) {
     return dsInitialOptExpected;
 
   if (eOptID == DECODER_OPTION_DATAFORMAT) { // Set color space of decoding output frame
-    if (m_pDecContext->pParam->bParseOnly) {
+    if (m_pDecContext->bParseOnly) {
       WelsLog (&m_pWelsTrace->m_sLogCtx, WELS_LOG_WARNING,
                "CWelsDecoder::SetOption for data format meaningless for parseonly.");
       return cmResultSuccess;
@@ -322,7 +318,7 @@ long CWelsDecoder::SetOption (DECODER_OPTION eOptID, void* pOption) {
     iVal = * ((int*)pOption); // int value for error concealment idc
     iVal = WELS_CLIP3 (iVal, (int32_t) ERROR_CON_DISABLE, (int32_t) ERROR_CON_SLICE_MV_COPY_CROSS_IDR_FREEZE_RES_CHANGE);
     m_pDecContext->pParam->eEcActiveIdc = m_pDecContext->eErrorConMethod = (ERROR_CON_IDC) iVal;
-    if ((m_pDecContext->pParam->bParseOnly) && (m_pDecContext->eErrorConMethod != ERROR_CON_DISABLE)) {
+    if ((m_pDecContext->bParseOnly) && (m_pDecContext->eErrorConMethod != ERROR_CON_DISABLE)) {
       WelsLog (&m_pWelsTrace->m_sLogCtx, WELS_LOG_INFO,
                "CWelsDecoder::SetOption for ERROR_CON_IDC = %d not allowd for parse only!.", iVal);
       return cmInitParaError;
diff --git a/test/decoder/DecUT_DecExt.cpp b/test/decoder/DecUT_DecExt.cpp
index e230d2ff..7b40d4b9 100644
--- a/test/decoder/DecUT_DecExt.cpp
+++ b/test/decoder/DecUT_DecExt.cpp
@@ -26,8 +26,6 @@ class DecoderInterfaceTest : public ::testing::Test {
   }
   //Init members
   void Init();
-  //Init valid members
-  void ValidInit();
   //Uninit members
   void Uninit();
   //Mock input data for test
@@ -99,29 +97,6 @@ void DecoderInterfaceTest::Init() {
     ASSERT_EQ (eRet, cmResultSuccess);
 }
 
-void DecoderInterfaceTest::ValidInit() {
-  memset (&m_sBufferInfo, 0, sizeof (SBufferInfo));
-  memset (&m_sDecParam, 0, sizeof (SDecodingParam));
-  m_sDecParam.pFileNameRestructed = NULL;
-  m_sDecParam.eOutputColorFormat = (EVideoFormatType) 23;
-  m_sDecParam.uiCpuLoad = 1;
-  m_sDecParam.uiTargetDqLayer = 1;
-  m_sDecParam.eEcActiveIdc = (ERROR_CON_IDC) (rand() & 7);
-  m_sDecParam.sVideoProperty.size = sizeof (SVideoProperty);
-  m_sDecParam.sVideoProperty.eVideoBsType = VIDEO_BITSTREAM_DEFAULT;
-
-  m_pData[0] = m_pData[1] = m_pData[2] = NULL;
-  m_szBuffer[0] = m_szBuffer[1] = m_szBuffer[2] = 0;
-  m_szBuffer[3] = 1;
-  m_iBufLength = 4;
-  CM_RETURN eRet = (CM_RETURN) m_pDec->Initialize (&m_sDecParam);
-  if ((m_sDecParam.eOutputColorFormat != videoFormatI420) &&
-      (m_sDecParam.eOutputColorFormat != videoFormatInternal))
-    ASSERT_EQ (eRet, cmUnsupportedData);
-  else
-    ASSERT_EQ (eRet, cmResultSuccess);
-}
-
 void DecoderInterfaceTest::Uninit() {
   if (m_pDec) {
     CM_RETURN eRet = (CM_RETURN) m_pDec->Uninitialize();
@@ -283,7 +258,7 @@ void DecoderInterfaceTest::TestEndOfStream() {
   int iTmp, iOut;
   CM_RETURN eRet;
 
-  ValidInit();
+  Init();
 
   //invalid input
   eRet = (CM_RETURN) m_pDec->SetOption (DECODER_OPTION_END_OF_STREAM, NULL);
@@ -345,7 +320,7 @@ void DecoderInterfaceTest::TestVclNal() {
   int iTmp, iOut;
   CM_RETURN eRet;
 
-  ValidInit();
+  Init();
 
   //Test SetOption
   //VclNal never supports SetOption
@@ -454,7 +429,7 @@ void DecoderInterfaceTest::TestGetDecStatistics() {
   SDecoderStatistics sDecStatic;
   int32_t iError = 0;
 
-  ValidInit();
+  Init();
   // setoption not support,
   eRet = (CM_RETURN)m_pDec->SetOption (DECODER_OPTION_GET_STATISTICS, NULL);
   EXPECT_EQ (eRet, cmInitParaError);
@@ -477,7 +452,7 @@ void DecoderInterfaceTest::TestGetDecStatistics() {
   Uninit();
 
   //Decoder error bs when the first IDR lost
-  ValidInit();
+  Init();
   iError = 2;
   m_pDec->SetOption (DECODER_OPTION_ERROR_CON_IDC, &iError);
   DecoderBs ("res/BA_MW_D_IDR_LOST.264");
@@ -495,7 +470,7 @@ void DecoderInterfaceTest::TestGetDecStatistics() {
   Uninit();
 
   //ecoder error bs when the first P lost
-  ValidInit();
+  Init();
   iError = 2;
   m_pDec->SetOption (DECODER_OPTION_ERROR_CON_IDC, &iError);
 
@@ -516,7 +491,7 @@ void DecoderInterfaceTest::TestGetDecStatistics() {
   //EC enable
 
   //EC Off UT just correc bitstream
-  ValidInit();
+  Init();
   iError = 0;
   m_pDec->SetOption (DECODER_OPTION_ERROR_CON_IDC, &iError);
   DecoderBs ("res/test_vd_1d.264");
diff --git a/test/decoder/DecUT_ParseSyntax.cpp b/test/decoder/DecUT_ParseSyntax.cpp
index ea6fcc63..776793c1 100644
--- a/test/decoder/DecUT_ParseSyntax.cpp
+++ b/test/decoder/DecUT_ParseSyntax.cpp
@@ -86,16 +86,13 @@ int32_t InitDecoder (const SDecodingParam* pParam, PWelsDecoderContext pCtx, SLo
       return cmMallocMemeError;
   }
 
-  pCtx->sLogCtx = *pLogCtx;
-
+  WELS_VERIFY_RETURN_PROC_IF (cmInitParaError, WelsInitDecoder (pCtx, pParam->bParseOnly, pLogCtx), UninitDecoder (pCtx));
   //check param and update decoder context
   pCtx->pParam = (SDecodingParam*) pCtx->pMemAlign->WelsMallocz (sizeof (SDecodingParam), "SDecodingParam");
   WELS_VERIFY_RETURN_PROC_IF (cmMallocMemeError, (NULL == pCtx->pParam), UninitDecoder (pCtx));
-  int32_t iRet = DecoderConfigParam (pCtx, pParam);
+  int32_t iRet = DecoderConfigParam (pCtx, pCtx->pParam);
   WELS_VERIFY_RETURN_IFNEQ (iRet, cmResultSuccess);
 
-  WELS_VERIFY_RETURN_PROC_IF (cmInitParaError, WelsInitDecoder (pCtx, pLogCtx), UninitDecoder (pCtx));
-
   return cmResultSuccess;
 }