tree 2af413688c79736dc565ceb955bd26ff19721a7b
parent 33697faa5bab5453d05de348a36e70f9eb06da04
author David Turner <david.turner@argondesign.com> 1550749830 +0000
committer David Turner <david.turner@argondesign.com> 1551091027 +0000

Refactor and explain reference frame management

In this commit I largely rewrite update_reference_frames() to make the
reference assignment strategy clearer.  This should make it easier to
identify the current reference assignment strategy and also easier to
modify it.

* Rename update_reference_frames() to update_ref_frame_map() to reflect
  the fact that this function no longer refreshes buffers or updates
  interp_filter_selected, it just updates remapped_ref_idx
* Setup the new reference map in a temporary array instead of in-place
  in order to save some juggling.
* Replace the shuffling functions (shift_last_ref_frames,
  rshift_bwd_ref_frames, lshift_bwd_ref_frames) with one simple
  assignment function (assign_new_map).  I want to make it clear that we
  aren't actually moving anything around, we are designing a new ref map
  based on the old one.
* Add a big comment to update_ref_frame_map() explaining the current
  reference management strategy (with pyramid and flat GOP structures).
* Replace the existing comments with more concise/consistent ones.
* Add comments to get_refresh_frame_flags() explaining how this logic
  links up with the reference management.

Change-Id: I1e69f94a3afd8707324d2b1cc3c17c47bb0d729d