Opened 9 years ago

Closed 9 years ago

#566 closed defect (fixed)

Uninitialized LambdaModifier is used for large GOP sizes

Reported by: rickard Owned by:
Priority: minor Milestone:
Component: HM Version: HM-7.0
Keywords: Cc: fbossen, ksuehring, davidf, jct-vc@…

Description

The code related to config parameters LambdaModifier0 through LambdaModifier3 has two problems.

First, the code does not use temporal_id to select what LambdaModifier to apply for a picture.This means that picture structures that are not dyadic will get incorrect lambdas if LambdaModifierX are specified.

Second, LambdaModifierX used for temporal layers above 3 are uninitialized. In practice, this may cause severe compression efficiency losses for some pictures when the GOP size is 16 or larger.

Neither of these problems affect any of the common condition picture structures.

The attached patch fixes the problem by adding new initialized parameters LambdaModifier4 through LambdaModifier7, and using the temporal layer as read from the config file as index instead of selecting LambdaModifier based on the GOP size.

Attachments (1)

FixFor566.patch (1.6 KB) - added by rickard 9 years ago.
Fix for #566

Download all attachments as: .zip

Change History (3)

comment:1 Changed 9 years ago by DefaultCC Plugin

  • Cc fbossen ksuehring davidf jct-vc@… added

Changed 9 years ago by rickard

Fix for #566

comment:2 Changed 9 years ago by fbossen

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

Fixed in r2462

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These roles will be notified: Reporter, Owner, Subscriber, Participant

  • David Flynn(Subscriber)
  • Frank Bossen(Subscriber, Participant)
  • jct-vc@…(Subscriber)
  • karl.sharman@…(Always)
  • Karsten Suehring(Subscriber, Always)
  • Rickard Sjoberg(Reporter)