Fix frame-decode errors. (#3723)

* Enable ReorderRefList2() which was added by the commit 1b8caef.

... and fix trivial issue of that function. This solves the some
frame decode error.

* Add workaround for frame decode error due to emulation byte.

* Fix a bug which seems due to a typo in WelsReorderRefList2()

This fixes the fuzzing test failure.

Addresses: #3772

Author: tyan0

codec/decoder/core/src/decoder.cpp

@@ -797,14 +797,13 @@ int32_t WelsDecodeBs (PWelsDecoderContext pCtx, const uint8_t* kpBsBuf, const in
           bNalStartBytes = true;
         } else if (pSrcNal[2 + iSrcIdx] == 0x03) {
           if ((3 + iSrcConsumed < iSrcLength) && pSrcNal[3 + iSrcIdx] > 0x03) {
-            pCtx->iErrorCode |= dsBitstreamError;
-            return pCtx->iErrorCode;
+            /* Just skip */
           } else {
             ST16 (pDstNal + iDstIdx, 0);
             iDstIdx      += 2;
-            iSrcIdx      += 3;
-            iSrcConsumed += 3;
           }
+          iSrcIdx      += 3;
+          iSrcConsumed += 3;
         } else { // 0x01
           bNalStartBytes = false;
 

codec/decoder/core/src/decoder_core.cpp

@@ -2440,7 +2440,7 @@ int32_t InitRefPicList (PWelsDecoderContext pCtx, const uint8_t kuiNRi, int32_t
   } else
     iRet = WelsInitRefList (pCtx, iPoc);
   if ((pCtx->eSliceType != I_SLICE && pCtx->eSliceType != SI_SLICE)) {
-#if 0
+#if 1
     if (pCtx->pSps->uiProfileIdc != 66 && pCtx->pPps->bEntropyCodingModeFlag)
       iRet = WelsReorderRefList2 (pCtx);
     else

codec/decoder/core/src/manage_dec_ref.cpp

@@ -494,7 +494,10 @@ int32_t WelsReorderRefList2 (PWelsDecoderContext pCtx) {
   int32_t i = 0;
   int32_t j = 0;
   int32_t k = 0;
-  int32_t iMaxRefIdx = pCtx->pSps->iNumRefFrames;
+  int32_t iMaxRefIdx = pCtx->iPicQueueNumber;
+  if (iMaxRefIdx > MAX_REF_PIC_COUNT) {
+    iMaxRefIdx = MAX_REF_PIC_COUNT;
+  }
   const int32_t iCurFrameNum = pSliceHeader->iFrameNum;
   const int32_t iMaxPicNum = 1 << pSliceHeader->pSps->uiLog2MaxFrameNum;
   int32_t iListCount = 1;
@@ -563,7 +566,7 @@ int32_t WelsReorderRefList2 (PWelsDecoderContext pCtx) {
           k = iCount;
           for (j = k; j <= iRefCount; j++) {
             if (ppRefList[j] != NULL) {
-              if (!ppRefList[j]->bIsLongRef || ppLongRefList[j]->uiLongTermPicNum != (uint32_t)iPredFrameNum)
+              if (!ppRefList[j]->bIsLongRef || ppRefList[j]->uiLongTermPicNum != (uint32_t)iPredFrameNum)
                 ppRefList[k++] = ppRefList[j];
             }
           }