diff --git a/codec/encoder/core/inc/wels_preprocess.h b/codec/encoder/core/inc/wels_preprocess.h
index 46045630..9144ae62 100644
--- a/codec/encoder/core/inc/wels_preprocess.h
+++ b/codec/encoder/core/inc/wels_preprocess.h
@@ -112,6 +112,7 @@ class CWelsPreProcess {
   void    FreeSpatialPictures (sWelsEncCtx* pCtx);
   int32_t WelsPreprocessStep1 (sWelsEncCtx* pEncCtx, const SSourcePicture** kppSrcPicList, const int32_t kiConfiguredLayerNum);
   int32_t WelsPreprocessStep3 (sWelsEncCtx* pEncCtx, const int32_t kiDIdx);
+  int32_t UpdateSpatialPictures(sWelsEncCtx* pEncCtx, SWelsSvcCodingParam* pParam, const int8_t iCurTid, const int32_t d_idx);
 
  private:
   int32_t WelsPreprocessCreate();
diff --git a/codec/encoder/core/src/encoder_ext.cpp b/codec/encoder/core/src/encoder_ext.cpp
index eda64037..3e539b70 100644
--- a/codec/encoder/core/src/encoder_ext.cpp
+++ b/codec/encoder/core/src/encoder_ext.cpp
@@ -3695,22 +3695,10 @@ int32_t WelsEncoderEncodeExt (sWelsEncCtx* pCtx, void* pDst, const SSourcePictur
     }
 
     if (iCurTid < pCtx->uiSpatialLayersInTemporal[d_idx] - 1 || pSvcParam->iDecompStages == 0) {
-      if ((iCurTid >= MAX_TEMPORAL_LEVEL) || (pCtx->uiSpatialLayersInTemporal[d_idx] - 1 > MAX_TEMPORAL_LEVEL)) {
-        ForceCodingIDR (pCtx);	// some logic error
+      if( pCtx->pVpp->UpdateSpatialPictures(pCtx, pSvcParam, iCurTid, d_idx) != 0 ){
+        ForceCodingIDR(pCtx);
         return -1;
       }
-
-      if (pSvcParam->bEnableLongTermReference && pCtx->bLongTermRefFlag[d_idx][iCurTid]) {
-        SPicture* tmp	= pCtx->pSpatialPic[d_idx][pCtx->uiSpatialLayersInTemporal[d_idx] + pCtx->pVaa->uiMarkLongTermPicIdx];
-        pCtx->pSpatialPic[d_idx][pCtx->uiSpatialLayersInTemporal[d_idx] + pCtx->pVaa->uiMarkLongTermPicIdx] =
-          pCtx->pSpatialPic[d_idx][iCurTid];
-        pCtx->pSpatialPic[d_idx][iCurTid] = pCtx->pSpatialPic[d_idx][pCtx->uiSpatialLayersInTemporal[d_idx] - 1];
-        pCtx->pSpatialPic[d_idx][pCtx->uiSpatialLayersInTemporal[d_idx] - 1] = tmp;
-        pCtx->bLongTermRefFlag[d_idx][iCurTid] = false;
-      } else {
-        WelsExchangeSpatialPictures (&pCtx->pSpatialPic[d_idx][pCtx->uiSpatialLayersInTemporal[d_idx] - 1],
-                                     &pCtx->pSpatialPic[d_idx][iCurTid]);
-      }
     }
 
     if (pSvcParam->bEnableLongTermReference && ((pCtx->pLtr[pCtx->uiDependencyId].bLTRMarkingFlag
diff --git a/codec/encoder/core/src/wels_preprocess.cpp b/codec/encoder/core/src/wels_preprocess.cpp
index 6d783a90..2d80a761 100644
--- a/codec/encoder/core/src/wels_preprocess.cpp
+++ b/codec/encoder/core/src/wels_preprocess.cpp
@@ -398,6 +398,25 @@ int32_t CWelsPreProcess::WelsPreprocessStep3 (sWelsEncCtx* pCtx, const int32_t k
   return 0;
 }
 
+int32_t CWelsPreProcess::UpdateSpatialPictures(sWelsEncCtx* pCtx, SWelsSvcCodingParam* pParam, 
+    const int8_t iCurTid, const int32_t d_idx) {
+  if ((iCurTid >= MAX_TEMPORAL_LEVEL) || (pCtx->uiSpatialLayersInTemporal[d_idx] - 1 > MAX_TEMPORAL_LEVEL)) {
+    return 1;
+  }
+  if (pParam->bEnableLongTermReference && pCtx->bLongTermRefFlag[d_idx][iCurTid]) {
+    SPicture* tmp	= pCtx->pSpatialPic[d_idx][pCtx->uiSpatialLayersInTemporal[d_idx] + pCtx->pVaa->uiMarkLongTermPicIdx];
+    pCtx->pSpatialPic[d_idx][pCtx->uiSpatialLayersInTemporal[d_idx] + pCtx->pVaa->uiMarkLongTermPicIdx] =
+    pCtx->pSpatialPic[d_idx][iCurTid];
+    pCtx->pSpatialPic[d_idx][iCurTid] = pCtx->pSpatialPic[d_idx][pCtx->uiSpatialLayersInTemporal[d_idx] - 1];
+    pCtx->pSpatialPic[d_idx][pCtx->uiSpatialLayersInTemporal[d_idx] - 1] = tmp;
+    pCtx->bLongTermRefFlag[d_idx][iCurTid] = false;
+  } else {
+    WelsExchangeSpatialPictures (&pCtx->pSpatialPic[d_idx][pCtx->uiSpatialLayersInTemporal[d_idx] - 1],
+                                 &pCtx->pSpatialPic[d_idx][iCurTid]);
+  }
+  return 0;
+}
+
 
 /*
 *	SingleLayerPreprocess: down sampling if applicable