Opened 3 years ago

Last modified 3 years ago

#113 new defect

wrong condtion on resampling

Reported by: kolya Owned by: Vadim
Priority: critical Milestone: SHM-12.0
Component: SHM software Version: SHM-11.0
Keywords: resampling, active refs Cc: Vadim, jct-vc@…

Description

below is decoder code:

#if SVC_EXTENSION
    // Create upsampling reference layer pictures for all possible dependent layers and do it only once for the first slice.
    // Other slices might choose which reference pictures to be used for inter-layer prediction
    if( m_layerId > 0 && m_uiSliceIdx == 0 && ( !pcSlice->getVPS()->getSingleLayerForNonIrapFlag() || pcSlice->isIRAP() ) )
    {
      // create buffers for scaling factors
      if( pcSlice->getNumILRRefIdx() )
      {
        m_pcPic->createMvScalingFactor(pcSlice->getNumILRRefIdx());
        m_pcPic->createPosScalingFactor(pcSlice->getNumILRRefIdx());
      }

      for( Int i = 0; i < '''pcSlice->getNumILRRefIdx()'''; i++ )

Spec and encoder tells that instead pcSlice->getNumILRRefIdx() getActiveNumILRRefIdx() shall be used

Change history (2)

comment:1 Changed 3 years ago by Vadim

Can you please elaborate on what is wrong? Please point out the spec part you are referring to, and what software is doing differently that it provides a normative mismatch to the spec.

My understanding of the current implementation is that it is done on a picture level rather than slice, since current resampling code is done per picture and to avoid repeating of the resampling for the slices that use the same inter-layer reference picture (ILRP).

Each slice may choose different ILR picture, so software prepares them all (possible ILRP) for the very first slice, some pictures may not be used, but it is just one possible way of the implementation.

comment:2 Changed 3 years ago by kolya

(in a hurry) the loop is over direct refs, not active
it seems these are different entities

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  • Gerhard Tech(Always)
  • jct-vc@…(Subscriber)
  • Karsten Suehring(Always)
  • Nikolay Shlyakhov(Reporter, Participant)
  • Vadim Seregin(Owner, Subscriber, Participant)