diff --git a/codec/encoder/core/inc/encoder.h b/codec/encoder/core/inc/encoder.h
index a2f1e84c..d4341e9b 100644
--- a/codec/encoder/core/inc/encoder.h
+++ b/codec/encoder/core/inc/encoder.h
@@ -81,9 +81,9 @@ int32_t InitFunctionPointers (SWelsFuncPtrList* pFuncList, SWelsSvcCodingParam*
 /*!
  * \brief	initialize frame coding
  */
-void InitFrameCoding (sWelsEncCtx* pEncCtx, const EFrameType keFrameType);
+void InitFrameCoding (sWelsEncCtx* pEncCtx, const EVideoFrameType keFrameType);
 
-EFrameType DecideFrameType (sWelsEncCtx* pEncCtx, const int8_t kiSpatialNum);
+EVideoFrameType DecideFrameType (sWelsEncCtx* pEncCtx, const int8_t kiSpatialNum);
 /*!
  * \brief	Dump reconstruction for dependency layer
  */
diff --git a/codec/encoder/core/inc/extern.h b/codec/encoder/core/inc/extern.h
index a7839453..bf4ad592 100644
--- a/codec/encoder/core/inc/extern.h
+++ b/codec/encoder/core/inc/extern.h
@@ -90,7 +90,7 @@ void WelsUninitEncoderExt (sWelsEncCtx** ppCtx);
  * \param	h			sWelsEncCtx*, encoder context
  * \param	pFbi			FrameBSInfo*
  * \param	kpSrcPic		Source picture
- * \return	EFrameType (WELS_FRAME_TYPE_IDR/WELS_FRAME_TYPE_I/WELS_FRAME_TYPE_P)
+ * \return	EFrameType (videoFrameTypeIDR/videoFrameTypeI/videoFrameTypeP)
  */
 int32_t WelsEncoderEncodeExt (sWelsEncCtx*, SFrameBSInfo * pFbi, const SSourcePicture* kpSrcPic);
 
diff --git a/codec/encoder/core/inc/wels_common_basis.h b/codec/encoder/core/inc/wels_common_basis.h
index 412734e1..a73c6178 100644
--- a/codec/encoder/core/inc/wels_common_basis.h
+++ b/codec/encoder/core/inc/wels_common_basis.h
@@ -137,17 +137,6 @@ extern const EVclType g_keTypeMap[32][2];
 #define IS_VCL_NAL_AVC_BASE(t)			( (t) == NAL_UNIT_CODED_SLICE || (t) == NAL_UNIT_CODED_SLICE_IDR )
 #define IS_NEW_INTRODUCED_SVC_NAL(t)	( (t) == NAL_UNIT_PREFIX || (t) == NAL_UNIT_CODED_SLICE_EXT )
 
-/*
- *	Frame types used in internal encoder (logic level based)
- */
-enum EFrameType {
-WELS_FRAME_TYPE_AUTO	= 0x0000,	/* Let encoder engine choose the proper type, RDO or scene change based */
-WELS_FRAME_TYPE_IDR		= 0x0001,	/* IDR, I frame with parameter sets */
-WELS_FRAME_TYPE_I		= 0x0002,	/* I Frame */
-WELS_FRAME_TYPE_P		= 0x0003,	/* P Frame */
-WELS_FRAME_TYPE_B		= 0x0004,	/* B Frame */
-WELS_FRAME_TYPE_SKIP	= 0x0008
-};
 
 /* Base SSlice Types
  * Invalid in case of eSliceType exceeds 9,
diff --git a/codec/encoder/core/src/encoder.cpp b/codec/encoder/core/src/encoder.cpp
index 5a49372c..a263d916 100644
--- a/codec/encoder/core/src/encoder.cpp
+++ b/codec/encoder/core/src/encoder.cpp
@@ -213,14 +213,14 @@ int32_t InitFunctionPointers (SWelsFuncPtrList* pFuncList, SWelsSvcCodingParam*
 /*!
  * \brief	initialize frame coding
  */
-void InitFrameCoding (sWelsEncCtx* pEncCtx, const EFrameType keFrameType) {
+void InitFrameCoding (sWelsEncCtx* pEncCtx, const EVideoFrameType keFrameType) {
   // for bitstream writing
   pEncCtx->iPosBsBuffer		= 0;	// reset bs pBuffer position
   pEncCtx->pOut->iNalIndex		= 0;	// reset NAL index
 
   InitBits (&pEncCtx->pOut->sBsWrite, pEncCtx->pOut->pBsBuffer, pEncCtx->pOut->uiSize);
 
-  if (keFrameType == WELS_FRAME_TYPE_P) {
+  if (keFrameType == videoFrameTypeP) {
     ++pEncCtx->iFrameIndex;
 
     if (pEncCtx->iPOC < (1 << pEncCtx->pSps->iLog2MaxPocLsb) - 2)     // if iPOC type is no 0, this need be modification
@@ -237,7 +237,7 @@ void InitFrameCoding (sWelsEncCtx* pEncCtx, const EFrameType keFrameType) {
     pEncCtx->eNalType		= NAL_UNIT_CODED_SLICE;
     pEncCtx->eSliceType	= P_SLICE;
     pEncCtx->eNalPriority	= NRI_PRI_HIGH;
-  } else if (keFrameType == WELS_FRAME_TYPE_IDR) {
+  } else if (keFrameType == videoFrameTypeIDR) {
     pEncCtx->iFrameNum		= 0;
     pEncCtx->iPOC			= 0;
     pEncCtx->bEncCurFrmAsIdrFlag = false;
@@ -252,7 +252,7 @@ void InitFrameCoding (sWelsEncCtx* pEncCtx, const EFrameType keFrameType) {
     // reset_ref_list
 
     // rc_init_gop
-  } else if (keFrameType == WELS_FRAME_TYPE_I) {
+  } else if (keFrameType == videoFrameTypeI) {
     if (pEncCtx->iPOC < (1 << pEncCtx->pSps->iLog2MaxPocLsb) - 2)     // if iPOC type is no 0, this need be modification
       pEncCtx->iPOC			+= 2;	// for POC type 0
     else
@@ -279,9 +279,9 @@ void InitFrameCoding (sWelsEncCtx* pEncCtx, const EFrameType keFrameType) {
 #endif//FRAME_INFO_OUTPUT
 }
 
-EFrameType DecideFrameType (sWelsEncCtx* pEncCtx, const int8_t kiSpatialNum) {
+EVideoFrameType DecideFrameType (sWelsEncCtx* pEncCtx, const int8_t kiSpatialNum) {
   SWelsSvcCodingParam* pSvcParam	= pEncCtx->pSvcParam;
-  EFrameType iFrameType = WELS_FRAME_TYPE_AUTO;
+  EVideoFrameType iFrameType = videoFrameTypeInvalid;
   bool bSceneChangeFlag = false;
 
   // perform scene change detection
@@ -297,12 +297,12 @@ EFrameType DecideFrameType (sWelsEncCtx* pEncCtx, const int8_t kiSpatialNum) {
   //bIdrPeriodFlag: RC disable || iSpatialNum != pSvcParam->iSpatialLayerNum
   //pEncCtx->bEncCurFrmAsIdrFlag: 1. first frame should be IDR; 2. idr pause; 3. idr request
   iFrameType = (pEncCtx->pVaa->bIdrPeriodFlag || bSceneChangeFlag
-                || pEncCtx->bEncCurFrmAsIdrFlag) ? WELS_FRAME_TYPE_IDR : WELS_FRAME_TYPE_P;
+                || pEncCtx->bEncCurFrmAsIdrFlag) ? videoFrameTypeIDR : videoFrameTypeP;
 
-  if (WELS_FRAME_TYPE_P == iFrameType && pEncCtx->iSkipFrameFlag > 0) {  // for frame skip, 1/5/2010
+  if (videoFrameTypeP == iFrameType && pEncCtx->iSkipFrameFlag > 0) {  // for frame skip, 1/5/2010
     -- pEncCtx->iSkipFrameFlag;
-    iFrameType = WELS_FRAME_TYPE_SKIP;
-  } else if (WELS_FRAME_TYPE_IDR == iFrameType) {
+    iFrameType = videoFrameTypeSkip;
+  } else if (videoFrameTypeIDR == iFrameType) {
     pEncCtx->iCodingIndex = 0;
   }
 
diff --git a/codec/encoder/core/src/encoder_ext.cpp b/codec/encoder/core/src/encoder_ext.cpp
index 43e874ba..dd0abc67 100644
--- a/codec/encoder/core/src/encoder_ext.cpp
+++ b/codec/encoder/core/src/encoder_ext.cpp
@@ -2538,14 +2538,14 @@ static inline void WelsSwapDqLayers (sWelsEncCtx* pCtx) {
 /*!
  * \brief	prefetch reference picture after WelsBuildRefList
  */
-static inline void PrefetchReferencePicture (sWelsEncCtx* pCtx, const EFrameType keFrameType) {
+static inline void PrefetchReferencePicture (sWelsEncCtx* pCtx, const EVideoFrameType keFrameType) {
   SSlice* pSliceBase = &pCtx->pCurDqLayer->sLayerInfo.pSliceInLayer[0];
   const int32_t kiSliceCount = GetCurrentSliceNum (pCtx->pCurDqLayer->pSliceEncCtx);
   int32_t iIdx = 0;
   uint8_t uiRefIdx = -1;
 
   assert (kiSliceCount > 0);
-  if (keFrameType != WELS_FRAME_TYPE_IDR) {
+  if (keFrameType != videoFrameTypeIDR) {
     assert (pCtx->iNumRef0 > 0);
     pCtx->pRefPic	= pCtx->pRefList0[0];	// always get item 0 due to reordering done
     pCtx->pCurDqLayer->pRefPic	= pCtx->pRefPic;
@@ -2859,7 +2859,7 @@ int32_t WelsEncoderEncodeParameterSets (sWelsEncCtx* pCtx, void* pDst) {
  * \pParam	pCtx			sWelsEncCtx*, encoder context
  * \pParam	pFbi			FrameBSInfo*
  * \pParam	pSrcPic			Source Picture
- * \return	EFrameType (WELS_FRAME_TYPE_IDR/WELS_FRAME_TYPE_I/WELS_FRAME_TYPE_P)
+ * \return	EFrameType (videoFrameTypeIDR/videoFrameTypeI/videoFrameTypeP)
  */
 int32_t WelsEncoderEncodeExt (sWelsEncCtx* pCtx, SFrameBSInfo * pFbi, const SSourcePicture* pSrcPic) {
   SLayerBSInfo* pLayerBsInfo					= &pFbi->sLayerInfo[0];
@@ -2880,7 +2880,7 @@ int32_t WelsEncoderEncodeExt (sWelsEncCtx* pCtx, SFrameBSInfo * pFbi, const SSou
   int32_t iNalLen[128]				= {0};
   int32_t iNalIdxInLayer			= 0;
   int32_t iCountNal					= 0;
-  EFrameType eFrameType				= WELS_FRAME_TYPE_AUTO;
+  EVideoFrameType eFrameType				= videoFrameTypeInvalid;
   int32_t iCurWidth					= 0;
   int32_t iCurHeight					= 0;
   EWelsNalUnitType eNalType			= NAL_UNIT_UNSPEC_0;
@@ -2903,12 +2903,12 @@ int32_t WelsEncoderEncodeExt (sWelsEncCtx* pCtx, SFrameBSInfo * pFbi, const SSou
   iSpatialNum = pCtx->pVpp->BuildSpatialPicList (pCtx, pSrcPic);
   if (iSpatialNum < 1) {	// skip due to temporal layer settings (different frame rate)
     ++ pCtx->iCodingIndex;
-    pFbi->eOutputFrameType = WELS_FRAME_TYPE_SKIP;
+    pFbi->eOutputFrameType = videoFrameTypeSkip;
     return ENC_RETURN_SUCCESS;
   }
 
   eFrameType = DecideFrameType (pCtx, iSpatialNum);
-  if (eFrameType == WELS_FRAME_TYPE_SKIP) {
+  if (eFrameType == videoFrameTypeSkip) {
     pFbi->eOutputFrameType = eFrameType;
     return ENC_RETURN_SUCCESS;
   }
@@ -2921,7 +2921,7 @@ int32_t WelsEncoderEncodeExt (sWelsEncCtx* pCtx, SFrameBSInfo * pFbi, const SSou
 
   pLayerBsInfo->pBsBuf	= pCtx->pFrameBs ;
 
-  if (eFrameType == WELS_FRAME_TYPE_IDR) {
+  if (eFrameType == videoFrameTypeIDR) {
     ++ pCtx->sPSOVector.uiIdrPicId;
     //if ( pSvcParam->bEnableSSEI )
 
@@ -3006,9 +3006,9 @@ int32_t WelsEncoderEncodeExt (sWelsEncCtx* pCtx, SFrameBSInfo * pFbi, const SSou
                                  (pSvcParam->bPrefixNalAddingCtrl ||
                                   (pSvcParam->iSpatialLayerNum > 1)));
 
-    if (eFrameType == WELS_FRAME_TYPE_P) {
+    if (eFrameType == videoFrameTypeP) {
       eNalType	= bAvcBased ? NAL_UNIT_CODED_SLICE : NAL_UNIT_CODED_SLICE_EXT;
-    } else if (eFrameType == WELS_FRAME_TYPE_IDR) {
+    } else if (eFrameType == videoFrameTypeIDR) {
       eNalType	= bAvcBased ? NAL_UNIT_CODED_SLICE_IDR : NAL_UNIT_CODED_SLICE_EXT;
     }
     if (iCurTid == 0 || pCtx->eSliceType == I_SLICE)
@@ -3037,7 +3037,7 @@ int32_t WelsEncoderEncodeExt (sWelsEncCtx* pCtx, SFrameBSInfo * pFbi, const SSou
       ForceCodingIDR (pCtx);
       WelsLog (pCtx, WELS_LOG_WARNING, "WelsEncoderEncodeExt(), WelsBuildRefList failed for P frames, pCtx->iNumRef0= %d. ForceCodingIDR!\n",
                pCtx->iNumRef0);
-      pFbi->eOutputFrameType = WELS_FRAME_TYPE_IDR;
+      pFbi->eOutputFrameType = videoFrameTypeIDR;
       pCtx->iEncoderError = ENC_RETURN_CORRECTED;
       return ENC_RETURN_CORRECTED;
     }
@@ -3338,7 +3338,7 @@ int32_t WelsEncoderEncodeExt (sWelsEncCtx* pCtx, SFrameBSInfo * pFbi, const SSou
              (iSpatialIdx == 0) ? "#AU" : "   ",
              pCtx->iPOC,
              pCtx->iFrameNum,
-             (uiFrameType == WELS_FRAME_TYPE_I || uiFrameType == WELS_FRAME_TYPE_IDR) ? "I" : "P",
+             (uiFrameType == videoFrameTypeI || uiFrameType == videoFrameTypeIDR) ? "I" : "P",
              iCurTid,
              iCurDid,
              0,
@@ -3452,7 +3452,7 @@ int32_t WelsEncoderEncodeExt (sWelsEncCtx* pCtx, SFrameBSInfo * pFbi, const SSou
     }
 
     if (pSvcParam->bEnableLongTermReference && ((pCtx->pLtr[pCtx->uiDependencyId].bLTRMarkingFlag
-        && (pCtx->pLtr[pCtx->uiDependencyId].iLTRMarkMode == LTR_DIRECT_MARK)) || eFrameType == WELS_FRAME_TYPE_IDR)) {
+        && (pCtx->pLtr[pCtx->uiDependencyId].iLTRMarkMode == LTR_DIRECT_MARK)) || eFrameType == videoFrameTypeIDR)) {
       pCtx->bLongTermRefFlag[d_idx][iCurTid] = true;
     }
   }
diff --git a/codec/encoder/core/src/ref_list_mgr_svc.cpp b/codec/encoder/core/src/ref_list_mgr_svc.cpp
index ec2dbcb8..a791f0b6 100644
--- a/codec/encoder/core/src/ref_list_mgr_svc.cpp
+++ b/codec/encoder/core/src/ref_list_mgr_svc.cpp
@@ -621,7 +621,7 @@ void WelsUpdateRefSyntax (sWelsEncCtx* pCtx, const int32_t iPOC, const int32_t u
     }
 
     /*syntax for dec_ref_pic_marking()*/
-    if (WELS_FRAME_TYPE_IDR == uiFrameType)		{
+    if (videoFrameTypeIDR == uiFrameType)		{
       pRefPicMark->bNoOutputOfPriorPicsFlag = false;
       pRefPicMark->bLongTermRefFlag = pCtx->pSvcParam->bEnableLongTermReference;
     } else {
diff --git a/codec/encoder/plus/src/welsEncoderExt.cpp b/codec/encoder/plus/src/welsEncoderExt.cpp
index 10c6b77e..49c64fa0 100644
--- a/codec/encoder/plus/src/welsEncoderExt.cpp
+++ b/codec/encoder/plus/src/welsEncoderExt.cpp
@@ -510,25 +510,8 @@ int CWelsH264SVCEncoder::EncodeFrame (const SSourcePicture* kpSrcPic, SFrameBSIn
   }
 
   const int32_t kiEncoderReturn = EncodeFrameInternal(kpSrcPic, pBsInfo);
-
-  switch (kiEncoderReturn) {
-  case ENC_RETURN_MEMALLOCERR:
-    WelsUninitEncoderExt (&m_pEncContext);
-    return cmMallocMemeError;
-  case ENC_RETURN_SUCCESS:
-  case ENC_RETURN_CORRECTED:
-    break;//continue processing
-  case ENC_RETURN_UNSUPPORTED_PARA:
-    return cmUnsupportedData;
-	break;
-  case ENC_RETURN_UNEXPECTED:
-    return cmUnkonwReason;
-  default:
-    WelsLog (m_pEncContext, WELS_LOG_ERROR, "unexpected return(%d) from WelsEncoderEncodeExt()!\n", kiEncoderReturn);
-    return cmUnkonwReason;
-  }
-
-
+  if(kiEncoderReturn != cmResultSuccess)
+    return kiEncoderReturn;
 #ifdef REC_FRAME_COUNT
   ++ m_uiCountFrameNum;
   WelsLog (m_pEncContext, WELS_LOG_INFO,
@@ -544,47 +527,23 @@ int CWelsH264SVCEncoder::EncodeFrame (const SSourcePicture* kpSrcPic, SFrameBSIn
 
 int CWelsH264SVCEncoder::EncodeFrameInternal(const SSourcePicture*  pSrcPic, SFrameBSInfo* pBsInfo) {
   if (!(pSrcPic && m_pEncContext && m_bInitialFlag) ){
-    return videoFrameTypeInvalid;
+    return cmInitParaError;
   }
 
-  int32_t iFrameTypeReturned = 0;
-  int32_t iFrameType = videoFrameTypeInvalid;
   const int32_t kiEncoderReturn = WelsEncoderEncodeExt (m_pEncContext, pBsInfo, pSrcPic);
 
   if(kiEncoderReturn == ENC_RETURN_MEMALLOCERR) {
     WelsUninitEncoderExt (&m_pEncContext);
-    return videoFrameTypeInvalid;
+    return cmMallocMemeError;
   }
   else if((kiEncoderReturn != ENC_RETURN_SUCCESS)&&(kiEncoderReturn == ENC_RETURN_CORRECTED)){
     WelsLog (m_pEncContext, WELS_LOG_ERROR, "unexpected return(%d) from EncodeFrameInternal()!\n", kiEncoderReturn);
-    return videoFrameTypeInvalid;
+    return cmUnkonwReason;
   }
 
-  iFrameTypeReturned = pBsInfo->eOutputFrameType;
-  switch (iFrameTypeReturned) {
-  case WELS_FRAME_TYPE_P:
-    iFrameType	= videoFrameTypeP;
-    break;
-  case WELS_FRAME_TYPE_IDR:
-    iFrameType	= videoFrameTypeIDR;
-    break;
-  case WELS_FRAME_TYPE_SKIP:
-    iFrameType	= videoFrameTypeSkip;
-    break;
-  case WELS_FRAME_TYPE_I:
-    iFrameType	= videoFrameTypeI;
-    break;
-  case WELS_FRAME_TYPE_AUTO:
-  case WELS_FRAME_TYPE_B: // not support B pictures
-    iFrameType	= videoFrameTypeInvalid;
-    break;
-  default:
-    break;
-  }
-  pBsInfo->eOutputFrameType = iFrameType;
   ///////////////////for test
 #ifdef OUTPUT_BIT_STREAM
-  if (iFrameType != videoFrameTypeInvalid && iFrameType != videoFrameTypeSkip) {
+  if (pBsInfo->eOutputFrameType != videoFrameTypeInvalid && pBsInfo->eOutputFrameType != videoFrameTypeSkip) {
     SLayerBSInfo* pLayer = NULL;
     int32_t i = 0, j = 0, iCurLayerBits = 0, total_bits = 0;
 
@@ -629,7 +588,7 @@ int CWelsH264SVCEncoder::EncodeFrameInternal(const SSourcePicture*  pSrcPic, SFr
   DumpSrcPicture (pSrcPicList[0]->pData[0]);
 #endif // DUMP_SRC_PICTURE
 
-  return kiEncoderReturn;
+  return cmResultSuccess;
 
 }