Opened 7 years ago

Closed 7 years ago

#1100 closed defect (invalid)

Calculation for PicWidthInCtbsY doesn't seem to match the spec

Reported by: jackh Owned by:
Priority: minor Milestone: HM-10.1
Component: HM Version: HM-10.0
Keywords: Cc: fbossen, ksuehring, davidf, jct-vc@…

Description

In TComSampleAdaptiveOffset::create(), there are four lines which I believe correspond to equations 7-15 and 7-17 in the spec:

  m_iNumCuInWidth  = m_iPicWidth / m_uiMaxCUWidth;
  m_iNumCuInWidth += ( m_iPicWidth % m_uiMaxCUWidth ) ? 1 : 0;

  m_iNumCuInHeight  = m_iPicHeight / m_uiMaxCUHeight;
  m_iNumCuInHeight += ( m_iPicHeight % m_uiMaxCUHeight ) ? 1 : 0;

Spec:

PicWidthInCtbsY = Ceil( pic_width_in_luma_samples ÷ CtbSizeY ) (7-15)
PicHeightInCtbsY = Ceil( pic_height_in_luma_samples ÷ CtbSizeY ) (7-17)

In order to match the spec, should these lines not read:

  m_iNumCuInWidth  = m_iPicWidth / m_uiMaxCUHeight;
  m_iNumCuInWidth += ( m_iPicWidth % m_uiMaxCUHeight ) ? 1 : 0;

  m_iNumCuInHeight  = m_iPicHeight / m_uiMaxCUHeight;
  m_iNumCuInHeight += ( m_iPicHeight % m_uiMaxCUHeight ) ? 1 : 0;

instead? Seems like the division should be by the same quantity for both equations.


Change History (4)

comment:1 Changed 7 years ago by DefaultCC Plugin

  • Cc fbossen ksuehring davidf jct-vc@… added

comment:2 Changed 7 years ago by bbross

There is no mismatch because m_uiMaxCUHeight is always equal to m_uiMaxCUWidth. That might become interesting again for the range extensions where you could have non-square coding blocks for 422 but for version 1, I see no issue here.

comment:3 Changed 7 years ago by jackh

You're right - I was misled because the issues addressed in ticket #1101 were overwriting memory, so the two variables were ending up with different contents. Apologies for the confusion.

comment:4 Changed 7 years ago by fbossen

  • Resolution set to invalid
  • Status changed from new to closed
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