diff --git a/codec/api/svc/codec_api.h b/codec/api/svc/codec_api.h
index 9c941c20..a91922f8 100644
--- a/codec/api/svc/codec_api.h
+++ b/codec/api/svc/codec_api.h
@@ -64,7 +64,7 @@ class ISVCEncoder {
   virtual int EXTAPI Uninitialize() = 0;
 
   /*
-   * return: EVideoFrameType [IDR: videoFrameTypeIDR; P: videoFrameTypeP; ERROR: videoFrameTypeInvalid]
+   * return: 0 - success; otherwise -failed;
    */
   virtual int EXTAPI EncodeFrame (const SSourcePicture* kpSrcPic, SFrameBSInfo* pBsInfo) = 0;
   /*
diff --git a/codec/api/svc/codec_def.h b/codec/api/svc/codec_def.h
index 233129b6..699f6dfe 100644
--- a/codec/api/svc/codec_def.h
+++ b/codec/api/svc/codec_def.h
@@ -75,6 +75,7 @@ typedef enum {
   cmUnkonwReason,
   cmMallocMemeError,                /*Malloc a memory error*/
   cmInitExpected,			  /*Initial action is expected*/
+  cmUnsupportedData,
 } CM_RETURN;
 
 
diff --git a/codec/encoder/core/src/encoder_ext.cpp b/codec/encoder/core/src/encoder_ext.cpp
index 6352cb26..7c8ff7ec 100644
--- a/codec/encoder/core/src/encoder_ext.cpp
+++ b/codec/encoder/core/src/encoder_ext.cpp
@@ -1730,8 +1730,8 @@ int32_t InitSliceSettings (SWelsSvcCodingParam* pCodingParam, const int32_t kiCp
       break;
     case SM_AUTO_SLICE:
       iMaxSliceCount = MAX_SLICES_NUM;
-	  pDlp->sSliceCfg.sSliceArgument.uiSliceNum = kiCpuCores;
-	  if (pDlp->sSliceCfg.sSliceArgument.uiSliceNum > iMaxSliceCount){
+      pDlp->sSliceCfg.sSliceArgument.uiSliceNum = kiCpuCores;
+      if (pDlp->sSliceCfg.sSliceArgument.uiSliceNum > iMaxSliceCount){
         pDlp->sSliceCfg.sSliceArgument.uiSliceNum = iMaxSliceCount;
       }
       if (pDlp->sSliceCfg.sSliceArgument.uiSliceNum == 1) {
diff --git a/codec/encoder/plus/src/welsEncoderExt.cpp b/codec/encoder/plus/src/welsEncoderExt.cpp
index 97d806d2..e7ea2ec5 100644
--- a/codec/encoder/plus/src/welsEncoderExt.cpp
+++ b/codec/encoder/plus/src/welsEncoderExt.cpp
@@ -508,11 +508,28 @@ int32_t CWelsH264SVCEncoder::RawData2SrcPic (const uint8_t* pSrc) {
  */
 int CWelsH264SVCEncoder::EncodeFrame (const SSourcePicture* kpSrcPic, SFrameBSInfo* pBsInfo) {
   if (! (kpSrcPic && m_pEncContext && m_bInitialFlag)) {
-    return videoFrameTypeInvalid;
+    return cmInitParaError;
+  }
+
+  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;
   }
 
-  int32_t uiFrameType = videoFrameTypeInvalid;
-  uiFrameType = EncodeFrameInternal(kpSrcPic, pBsInfo);
 
 #ifdef REC_FRAME_COUNT
   ++ m_uiCountFrameNum;
@@ -523,8 +540,7 @@ int CWelsH264SVCEncoder::EncodeFrame (const SSourcePicture* kpSrcPic, SFrameBSIn
 #ifdef DUMP_SRC_PICTURE
   DumpSrcPicture (pSrc);
 #endif // DUMP_SRC_PICTURE
-
-  return uiFrameType;
+  return cmResultSuccess;
 }
 
 
@@ -539,18 +555,12 @@ int CWelsH264SVCEncoder::EncodeFrameInternal(const SSourcePicture*  pSrcPic, SFr
   const int32_t kiEncoderReturn = WelsEncoderEncodeExt (m_pEncContext, pBsInfo, pSrcPic);
   XMMREG_PROTECT_LOAD(CWelsH264SVCEncoder);
 
-  switch (kiEncoderReturn) {
-  case ENC_RETURN_MEMALLOCERR:
+  if(kiEncoderReturn == ENC_RETURN_MEMALLOCERR) {
     WelsUninitEncoderExt (&m_pEncContext);
     return videoFrameTypeInvalid;
-  case ENC_RETURN_SUCCESS:
-  case ENC_RETURN_CORRECTED:
-    break;//continue processing
-  case ENC_RETURN_UNSUPPORTED_PARA:
-  case ENC_RETURN_UNEXPECTED:
-    return videoFrameTypeInvalid;
-  default:
-    WelsLog (m_pEncContext, WELS_LOG_ERROR, "unexpected return(%d) from WelsEncoderEncodeExt()!\n", kiEncoderReturn);
+  }
+  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;
   }
 
@@ -576,8 +586,6 @@ int CWelsH264SVCEncoder::EncodeFrameInternal(const SSourcePicture*  pSrcPic, SFr
     break;
   }
 
-
-
   ///////////////////for test
 #ifdef OUTPUT_BIT_STREAM
   if (iFrameType != videoFrameTypeInvalid && iFrameType != videoFrameTypeSkip) {
@@ -625,7 +633,7 @@ int CWelsH264SVCEncoder::EncodeFrameInternal(const SSourcePicture*  pSrcPic, SFr
   DumpSrcPicture (pSrcPicList[0]->pData[0]);
 #endif // DUMP_SRC_PICTURE
 
-  return iFrameType;
+  return kiEncoderReturn;
 
 }
 
diff --git a/test/BaseEncoderTest.cpp b/test/BaseEncoderTest.cpp
index 575174ba..1eb7d8fd 100644
--- a/test/BaseEncoderTest.cpp
+++ b/test/BaseEncoderTest.cpp
@@ -83,8 +83,8 @@ void BaseEncoderTest::EncodeStream(InputStream* in, int width, int height,
   pic.pData[2] = pic.pData[1] + (width*height>>2);
   while (in->read(buf.data(), frameSize) == frameSize) {
     rv = encoder_->EncodeFrame(&pic, &info);
-    ASSERT_TRUE(rv != videoFrameTypeInvalid);
-    if (rv != videoFrameTypeSkip && cbk != NULL) {
+    ASSERT_TRUE(rv == cmResultSuccess);
+    if (info.eOutputFrameType != videoFrameTypeSkip && cbk != NULL) {
       cbk->onEncodeFrame(info);
     }
   }