JVET-Q0179: Scaling window size constraint for constraining worst case memory bandwidth

source/Lib/CommonLib/TypeDef.h

@@ -50,6 +50,8 @@
 #include <assert.h>
 #include <cassert>
 
+#define JVET_Q0179_SCALING_WINDOW_SIZE_CONSTRAINT         1 // JVET-Q0179: Scaling window size constraint for constraining worst case memory bandwidth
+
 #define JVET_Q0504_PLT_NON444                             1 // JVET-Q0504: enable palette mode for non 444 color format
 
 #define JVET_Q0089_SLICE_LOSSLESS_CODING_CHROMA_BDPCM     1 // JVET-Q0089: RRC slice-level switch for lossless coding and one SPS flag for luma and chroma BDPCM.

source/Lib/CommonLib/UnitTools.cpp

@@ -123,6 +123,17 @@ bool CU::getRprScaling( const SPS* sps, const PPS* curPPS, Picture* refPic, int&
   xScale = ( ( refPicWidth << SCALE_RATIO_BITS ) + ( curPicWidth >> 1 ) ) / curPicWidth;
   yScale = ( ( refPicHeight << SCALE_RATIO_BITS ) + ( curPicHeight >> 1 ) ) / curPicHeight;
 
+#if JVET_Q0179_SCALING_WINDOW_SIZE_CONSTRAINT
+  int curSeqMaxPicWidthY = sps->getMaxPicWidthInLumaSamples();                  // pic_width_max_in_luma_samples
+  int curSeqMaxPicHeightY = sps->getMaxPicHeightInLumaSamples();                // pic_height_max_in_luma_samples
+  int curPicWidthY = curPPS->getPicWidthInLumaSamples();                        // pic_width_in_luma_samples
+  int curPicHeightY = curPPS->getPicHeightInLumaSamples();                      // pic_height_in_luma_samples 
+  int max8MinCbSizeY = std::max((int)8, (1<<sps->getLog2MinCodingBlockSize())); // Max(8, MinCbSizeY)
+
+  CHECK((curPicWidth * curSeqMaxPicWidthY) < refPicWidth * (curPicWidthY - max8MinCbSizeY), "(curPicWidth * curSeqMaxPicWidthY) should be greater than or equal to refPicWidth * (curPicWidthY - max8MinCbSizeY))");
+  CHECK((curPicHeight * curSeqMaxPicHeightY) < refPicHeight * (curPicHeightY - max8MinCbSizeY), "(curPicHeight * curSeqMaxPicHeightY) should be greater than or equal to refPicHeight * (curPicHeightY - max8MinCbSizeY))");
+#endif
+
 #if JVET_Q0487_SCALING_WINDOW_ISSUES
   return refPic->isRefScaled( curPPS );
 #else