id,summary,reporter,owner,description,type,status,priority,milestone,component,version,resolution,keywords,cc 1481,computation overflow in HM reference C model,swong10,swong10,"We may have found a bug in the HM model. There is a mismatch between the written specification and HM reference C model. Dec 2016 Spec: 8.4.4.2.7 Decoding process for palette mode HM code version : HM-16.15+SCM-8.5 Function : TDecCu::xDecodePaletteTexture() in TDecCu.cpp The problem equation happens in both clauses of an if-else statement. The overflow happens in tmpVal, which is used to store the inverse quantized palette escape values in (8-77). tmpVal is then clipped according to (8-78) to generate the reconstructed samples. levelScale <= 72 (7-bit). In SCM, tmpVal is of type “Pel”. So, once we changed Pixel from Short to Int the overflow was fixed. It is a high bit depth problem, most likely only happen when pixel depth is > 8-bit. ",defect,closed,major,,HM SCC,,fixed,"overflow, palette",jct-vc@…