Add pruning for refinemv, INTERINTRA, and WARP_DELTA

[yeqing-wu]

Enables three ref-index based pruning speed features at speed >= 1:

• prune_refinemv_by_ref_idx: skip refinemv_loop == 1 for ref-pairs other than (0, 1).
• prune_interintra_by_ref_idx: skip INTERINTRA motion mode when ref_frame[0] > 1.
• prune_warp_delta_by_ref_idx: skip WARP_DELTA motion mode when ref_frame[0] > 2.

STATS_CHANGED

Anchor: commit 165345b
Speed 1 (cpu-used=1): FG16 CTC (33 frames, class A1 and A2, RA)
Speed 4 (cpu-used=4): FG16 CTC (33 frames, class A1 and A2, RA)

1) Speed 1

  a) Overall performance (all three features combined)

  +------------+------+-------+-------+------+------+------+
  | Class      |    Y |    Cb |    Cr | wAvg | Enc% | Dec% |
  +------------+------+-------+-------+------+------+------+
  | A1         | 0.02 | -0.15 |  0.05 | 0.01 |   93 |  101 |
  | A2         | 0.12 |  0.36 | -0.03 | 0.12 |   93 |  100 |
  | Avg w/o B2 | 0.09 |  0.21 | -0.00 | 0.09 |   93 |  100 |
  +------------+------+-------+-------+------+------+------+

  b) Performance of prune_refinemv_by_ref_idx only

  +------------+-------+-------+-------+-------+------+------+
  | Class      |     Y |    Cb |    Cr |  wAvg | Enc% | Dec% |
  +------------+-------+-------+-------+-------+------+------+
  | A1         | -0.01 | -0.14 | -0.34 | -0.04 |   99 |  101 |
  | A2         |  0.04 |  0.06 | -0.25 |  0.02 |   99 |  100 |
  | Avg w/o B2 |  0.02 |  0.00 | -0.28 |  0.00 |   99 |  100 |
  +------------+-------+-------+-------+-------+------+------+

  c) Performance of prune_interintra_by_ref_idx only

  +------------+------+-------+------+------+------+------+
  | Class      |    Y |    Cb |   Cr | wAvg | Enc% | Dec% |
  +------------+------+-------+------+------+------+------+
  | A1         | 0.04 | -0.02 | 0.04 | 0.04 |   98 |  100 |
  | A2         | 0.02 |  0.27 | 0.08 | 0.03 |   98 |  100 |
  | Avg w/o B2 | 0.03 |  0.18 | 0.07 | 0.03 |   98 |  100 |
  +------------+------+-------+------+------+------+------+

  d) Performance of prune_warp_delta_by_ref_idx only

  +------------+------+------+-------+------+------+------+
  | Class      |    Y |   Cb |    Cr | wAvg | Enc% | Dec% |
  +------------+------+------+-------+------+------+------+
  | A1         | 0.03 | 0.00 |  0.12 | 0.03 |   95 |  101 |
  | A2         | 0.07 | 0.11 | -0.07 | 0.07 |   96 |  100 |
  | Avg w/o B2 | 0.06 | 0.08 | -0.01 | 0.06 |   96 |  100 |
  +------------+------+------+-------+------+------+------+

2) Speed 4

  Overall performance (all three features combined)

  +------------+-------+-------+-------+-------+------+------+
  | Class      |     Y |    Cb |    Cr |  wAvg | Enc% | Dec% |
  +------------+-------+-------+-------+-------+------+------+
  | A1         | -0.01 | -0.09 | -0.01 | -0.02 |   90 |  101 |
  | A2         |  0.14 |  0.33 |  0.18 |  0.14 |   89 |  101 |
  | Avg w/o B2 |  0.09 |  0.20 |  0.12 |  0.09 |   89 |  101 |
  +------------+------+-------+-------+-------+------+------+

[yeqing-wu]

Hello all,

Could you please review this PR? The code has been rebased on top of av2enc branch, which includes the PR #5114.

Thanks
Yeqing

[leolzhao]

LGTM.