Opened 4 years ago

Closed 4 years ago

#889 closed defect (fixed)

Incorrect size and reset for m_weightPredTable

Reported by: audrey.turquin Owned by:
Priority: minor Milestone:
Component: VTM Version:
Keywords: Cc: ksuehring, XiangLi, fbossen, jvet@…


Since the introduction of the syntax elements num_l0_weights and num_l1_weights in the PH, the size of m_weightPredTable is not correct anymore.

According to the specification text, num_l0_weights and num_l1_weights shall be in the range 0 to num_ref_entries.
num_ref_entries can be up to MaxDpbSize + 13. So, at the maximum num_ref_entries can be equal to 16 + 13 = 29.

However, in the VTM, the size of m_weightPredTable is limited to MAX_NUM_REF = 16, which is not enough.
The size of m_weightPredTable should be increased to 29.

Moreover, a reset of m_weightPredTable at picture header level is missing.

Change history (4)

comment:1 Changed 4 years ago by ksuehring

comment:2 Changed 4 years ago by audrey.turquin

This is indeed related to this issue.
However in the size of m_weightPredTable, this is MAX_NUM_REF which is used, and the MR you pointed out changes MAX_NUM_REF_PICS. So the MR would not fix this issue, unless we make the change to use MAX_NUM_REF_PICS to set the size of m_weightPredTable.

I wonder if there is some confusion in using MAX_NUM_REF or MAX_NUM_REF_PICS in the VTM as the use doesn't match the comment (but it is seemless as both constants have the same value for the moment).
Maybe one should be renamed to have a 'MAX_NUM_REF_ENTRIES' (=29) which is more clear ?

comment:4 Changed 4 years ago by audrey.turquin

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

The spec has been changed to do not allow values greater than 15.
(see ticket
This solves the issue and the VTM no longer needs to be fixed.

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