DRAFT: Rebase av2enc first milestone on main - #5330

These functions are only needed by the encoder.

Only assign pc_tree->partitioning = partition when last_part_rdc
represents a valid RDO search result.
Guard the do_recon block so reconstruction is only attempted on a valid
partition.

Fixes AOMediaCodec#5092

Co-authored-by: Urvang Joshi <urvang@google.com>

…5098)

Drive the main inter-mode loop in av2_rd_pick_inter_mode_sb from a
static ref-frame-centric LUT and revise the motion-mode pruning
heuristic.

STATS_CHANGED

Anchor: commit 165345b
Speed 1 (cpu-used=1): FG16 CTC (33 frames, class A1 and A2, RA)
Speed 0 (cpu-used=0): VCWG CTC (130 frames, all classes, RA and LD).
Speed 4 (cpu-used=4): FG16 CTC (33 frames, class A1 and A2, RA)

```
1) This change in isolation (loop restructure + motion-mode pruning).

  Speed 1 (cpu-used=1), RA:
  +------------+------+-------+-------+------+------+------+
  | Class      |    Y |    Cb |    Cr | wAvg | Enc% | Dec% |
  +------------+------+-------+-------+------+------+------+
  | A1         | 0.18 | -0.03 | -0.20 | 0.14 |   95 |  101 |
  | A2         | 0.18 |  0.67 |  0.35 | 0.20 |   93 |  100 |
  | Avg w/o B2 | 0.18 |  0.47 |  0.19 | 0.18 |   94 |  100 |
  +------------+------+-------+-------+------+------+------+

  Speed 0 (cpu-used=0), RA:
  +------------+-------+-------+-------+-------+------+------+
  | Class      |     Y |    Cb |    Cr |  wAvg | Enc% | Dec% |
  +------------+-------+-------+-------+-------+------+------+
  | A1         | -0.01 |  0.05 | -0.05 | -0.01 |  100 |  101 |
  | A2         |  0.01 |  0.02 |  0.06 |  0.01 |  100 |  100 |
  | A3         |  0.00 |  0.01 |  0.10 |  0.01 |  100 |  100 |
  | A4         | -0.02 |  0.01 | -0.51 | -0.03 |   99 |  100 |
  | A5         | -0.01 | -0.50 |  0.05 | -0.03 |  101 |  100 |
  | B1         |  0.05 |  0.18 | -0.04 |  0.04 |  100 |  101 |
  | B2         |  0.36 |  0.36 |  0.32 |  0.36 |  101 |  108 |
  | Avg w/o B2 |  0.01 |  0.01 | -0.03 |  0.00 |  100 |  100 |
  +------------+-------+-------+-------+-------+------+------+

  Speed 0 (cpu-used=0), LD:
  +------------+-------+-------+-------+-------+------+------+
  | Class      |     Y |    Cb |    Cr |  wAvg | Enc% | Dec% |
  +------------+-------+-------+-------+-------+------+------+
  | A2         |  0.02 | -0.01 | -0.14 |  0.01 |  100 |  100 |
  | A3         | -0.03 |  0.01 |  0.63 | -0.01 |  101 |  101 |
  | A4         | -0.00 | -0.26 | -1.13 | -0.05 |  100 |  100 |
  | A5         |  0.16 |  0.60 |  0.05 |  0.16 |  102 |  103 |
  | B1         |  0.02 | -0.07 | -0.03 |  0.01 |  101 |  100 |
  | B2         |  0.36 |  0.34 |  0.61 |  0.38 |  101 |  102 |
  | Avg w/o B2 |  0.02 |  0.00 | -0.10 |  0.01 |  101 |  100 |
  +------------+-------+-------+-------+-------+------+------+

2) For reference, the two follow-up commits (single-ref to compound
   pruning, and per-ref RD-based pruning for single-ref NEWMV /
   WARP_NEWMV) combined, Speed 1 (cpu-used=1), RA:
  +------------+------+-------+-------+------+------+------+
  | Class      |    Y |    Cb |    Cr | wAvg | Enc% | Dec% |
  +------------+------+-------+-------+------+------+------+
  | A1         | 0.20 | -0.08 | -0.06 | 0.16 |   83 |  102 |
  | A2         | 0.22 |  0.53 |  0.15 | 0.23 |   84 |  101 |
  | Avg w/o B2 | 0.22 |  0.35 |  0.09 | 0.21 |   84 |  101 |
  +------------+------+-------+-------+------+------+------+

3) Overall, motion-mode pruning stacked on top of (2),
   Speed 1 (cpu-used=1), RA:
  +------------+------+------+-------+------+------+------+
  | Class      |    Y |   Cb |    Cr | wAvg | Enc% | Dec% |
  +------------+------+------+-------+------+------+------+
  | A1         | 0.31 | 0.29 | -0.20 | 0.28 |   80 |  101 |
  | A2         | 0.32 | 0.90 |  0.58 | 0.35 |   80 |  100 |
  | Avg w/o B2 | 0.32 | 0.72 |  0.35 | 0.33 |   80 |  100 |
  +------------+------+------+-------+------+------+------+

4) Overall, motion-mode pruning, single-ref to compound pruning, and
   per-ref RD-based pruning for single-ref NEWMV / WARP_NEWMV
   combined, Speed 4 (cpu-used=4), RA:
  +------------+------+------+------+------+------+------+
  | Class      |    Y |   Cb |   Cr | wAvg | Enc% | Dec% |
  +------------+------+------+------+------+------+------+
  | A1         | 0.27 | 0.17 | 0.00 | 0.24 |   82 |  102 |
  | A2         | 0.42 | 0.63 | 0.15 | 0.42 |   81 |  102 |
  | Avg w/o B2 | 0.38 | 0.49 | 0.11 | 0.36 |   81 |  102 |
  +------------+------+------+------+------+------+------+
```

The intra chroma component will not use FSC mode. Simplify the encoding
functions therein.

Revive prune_compound_using_single_ref: refresh the per-ref RD
snapshot every iteration and prune compound (refs[0], refs[1]) pairs
via the single-ref RD cutoff. Enabled at speed >= 1.

STATS_CHANGED

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

```
  +------------+------+-------+-------+------+------+------+
  | Class      |    Y |    Cb |    Cr | wAvg | Enc% | Dec% |
  +------------+------+-------+-------+------+------+------+
  | A1         | 0.10 | -0.15 | -0.27 | 0.07 |   92 |  101 |
  | A2         | 0.09 |  0.28 | -0.12 | 0.08 |   93 |  101 |
  | Avg w/o B2 | 0.09 |  0.15 | -0.17 | 0.08 |   93 |  101 |
  +------------+------+-------+-------+------+------+------+
```

…odec#5114)

Tighten the loop lower bound to pb_mv_precision + 1 so the found cache
precision is strictly greater than the current pb_mv_precision, matching
the assert's intent.

…iaCodec#5100)

Prune single-ref NEWMV / WARP_NEWMV trials whose prior-mode RD for
the current ref frame is far from the best across all refs. Gated by
prune_newmv_modes_using_prior_rd, enabled at speed >= 1.

STATS_CHANGED

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

```
  +------------+------+-------+-------+------+------+------+
  | Class      |    Y |    Cb |    Cr | wAvg | Enc% | Dec% |
  +------------+------+-------+-------+------+------+------+
  | A1         | 0.14 | -0.04 | -0.14 | 0.11 |   88 |  101 |
  | A2         | 0.17 |  0.66 |  0.10 | 0.18 |   88 |  101 |
  | Avg w/o B2 | 0.16 |  0.45 |  0.03 | 0.16 |   88 |  101 |
  +------------+------+-------+-------+------+------+------+
```

Adds three single-ref NEWMV DRL search speed features, enabled at speed
>= 1:

* mv_sf.skip_second_best_subpel: the subpel search normally refines both
the best and the second-best full-pel candidate and keeps the
lower-variance result; with this feature set, only the best full-pel
candidate is refined.

* mv_sf.predict_repeated_newmv: when a previously searched ref_mv_idx
has a reference MV within one full pel of the current one, reuse the
cached NEWMV result and only recompute the MV rate, avoiding the
full-pel and subpel search entirely.

* mv_sf.newmv_drl_search_limit: once ref_mv_idx reaches the limit, reuse
the nearest already-searched result regardless of ref-MV distance
instead of running a fresh search. Enabled with a cap of 2. Shares the
same search-loop pass as the predict_repeated_newmv reuse.

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         | 0.04 | -0.08 | -0.36 | 0.00 |   99 |  101 |
  | A2         | 0.04 | -0.04 | -0.18 | 0.03 |   98 |  100 |
  | Avg w/o B2 | 0.04 | -0.05 | -0.23 | 0.02 |   98 |  100 |
  +------------+------+-------+-------+------+------+------+

  b) Performance of skip_second_best_subpel only

  +------------+-------+-------+-------+-------+------+------+
  | Class      |     Y |    Cb |    Cr |  wAvg | Enc% | Dec% |
  +------------+-------+-------+-------+-------+------+------+
  | A1         | -0.10 | -0.32 |  0.09 | -0.11 | 99.5 |  101 |
  | A2         | -0.01 | -0.09 | -0.34 | -0.02 | 99.5 |  100 |
  | Avg w/o B2 | -0.04 | -0.16 | -0.21 | -0.05 | 99.5 |  100 |
  +------------+-------+-------+-------+-------+------+------+

  c) Performance of predict_repeated_newmv only

  +------------+-------+-------+-------+-------+------+------+
  | Class      |     Y |    Cb |    Cr |  wAvg | Enc% | Dec% |
  +------------+-------+-------+-------+-------+------+------+
  | A1         |  0.00 | -0.08 |  0.08 |  0.00 |  100 |  100 |
  | A2         | -0.03 | -0.04 | -0.04 | -0.03 |  100 |  100 |
  | Avg w/o B2 | -0.02 | -0.05 | -0.00 | -0.02 |  100 |  100 |
  +------------+-------+-------+-------+-------+------+------+

  d) Performance of newmv_drl_search_limit only

  +------------+------+-------+------+------+------+------+
  | Class      |    Y |    Cb |   Cr | wAvg | Enc% | Dec% |
  +------------+------+-------+------+------+------+------+
  | A1         | 0.05 | -0.17 | 0.09 | 0.03 |   99 |  101 |
  | A2         | 0.00 |  0.36 | 0.01 | 0.02 |   99 |  100 |
  | Avg w/o B2 | 0.01 |  0.20 | 0.03 | 0.02 |   99 |  100 |
  +------------+------+-------+------+------+------+------+

2) Speed 4

  Overall performance (all three features combined)

  +------------+------+-------+-------+------+------+------+
  | Class      |    Y |    Cb |    Cr | wAvg | Enc% | Dec% |
  +------------+------+-------+-------+------+------+------+
  | A1         | 0.01 | -0.13 |  0.07 | 0.00 |   96 |  101 |
  | A2         | 0.05 | -0.13 | -0.25 | 0.03 |   96 |  100 |
  | Avg w/o B2 | 0.04 | -0.13 | -0.15 | 0.02 |   96 |  100 |
  +------------+------+-------+-------+------+------+------+
```

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 |
  +------------+------+-------+-------+-------+------+------+
```

…5103)

Extend the intra-luma IST/STX pre-skip and post-trellis gates to cover
eob == 0 in addition to the existing eob == 1 (DC-only) case. The eob ==
0 branch kills candidates only when stx > 0, so a non-DCT primary with
stx == 0 that quantizes to all-zero can still win via skip coding.

Add a pre-quant L-infinity gate that predicts primary FP-quant eob = 0
directly from the post-primary coefficients (max |coeff| below the FP
quantizer kill threshold min(dq0, dq1) >> (4 + log_scale)). When fired,
av2_quant + av2_optimize_b + cost_coeffs are skipped and the same
eob_found / DCT_DCT propagation as the post-quant gate is applied.
Scoped to intra Y, stx == 0, non-DC-only, IST-enabled, non-QM blocks.

Gated behind a new tx_sf.prune_intra_ist_stx_by_zero_eob flag, off by
default and enabled at speed >= 1. Encoding at speed 0 is unchanged from
the baseline.

STATS_CHANGED

Anchor: commit dd84ac9
Speed 1 (cpu-used=1): FG16 CTC (33 frames, RA)

```
  +------------+-------+-------+-------+-------+------+------+
  | Class      |     Y |    Cb |    Cr |  wAvg | Enc% | Dec% |
  +------------+-------+-------+-------+-------+------+------+
  | A1         |  0.06 | -0.20 | -0.34 |  0.02 |   98 |  100 |
  | A2         |  0.09 | -0.18 | -0.12 |  0.07 |   97 |  100 |
  | A3         |  0.05 |  0.58 |  0.48 |  0.07 |   96 |   99 |
  | A4         |  0.09 |  0.22 | -3.02 | -0.01 |   97 |   99 |
  | A5         | -0.12 | -2.35 |  2.22 | -0.12 |   97 |  101 |
  | B1         |  0.14 | -0.94 | -0.28 |  0.09 |   97 |  101 |
  | B2         | -0.48 | -0.71 |  0.30 | -0.46 |   97 |   97 |
  | Avg w/o B2 |  0.07 | -0.32 | -0.24 |  0.04 |   97 |  100 |
  +------------+-------+-------+-------+-------+------+------+
```

Make it properly handle cctx cases.

Take out coeff dropout to be consistent with what's used in RD search
stage.

Re-do u plane if its eob is different from that's in RD search to avoid
potential mismatch issues due to the change of cctx_type.

Tested for A2 and A4 in speed 1 with 33 frames. No coding stats change
observed.

The unit tests that exercised base-only implicit-ref-map decode of a
multi-layer bitstream (the only path where a TIP-winning base-layer
block would fail to reconstruct) were removed in 9f0dfe5 (Fix setting in
multi_layers tests, AOMediaCodec#5116), so this encoder-side workaround is no longer
needed.

Fixed issue AOMediaCodec#5122

Skip process_compound_inter() function for opfl modes.

Tests - cpu-used =1
Anchor:
AOMediaCodec@6e71b0c
Results (RA):

A1 - 17 frames
A2 - 33 frames

<img width="1066" height="101" alt="MR7"
src="https://github.com/user-attachments/assets/7e9e4bce-1065-4d28-84bc-a8df8f3479a7"
/>

…search (AOMediaCodec#5125)

Enable winner transform search

Add small fix for winner transform

Disable 4 way and 5 way transform in rough search and enable in winner

Set winner transform candidates to three

Disable existing winner transform speed features.

Tests - cpu-used =1
Anchor: 6e71b0c
Results (RA): 

A1 - 17 frames
A2 - 33 frames

<pre>
+---------+-------+--------+-------+-------+----------+----------+
| Summary |   Y   |   U    |   V   |  YUV  | Enc-time | Dec-time |
+---------+-------+--------+-------+-------+----------+----------+
| A1      | 0.13% | 0.01%  | 0.20% | 0.13% | 93.6%    | 100%   |
| A2      | 0.17% | -0.15% | 0.06% | 0.15% | 92.3%    | 100%   |
+---------+-------+--------+-------+-------+----------+----------+
</pre>

Squash merge branch 'leo/inter-sdp-mr' into 'avm-encoder-development'
Add a speed level for inter sdp fast method:

1) Early terminate inter-sdp when there is no intra coded blocks in the
this region after searching mixed intra and inter region;
2) Early terminate inter-sdp when more than half of the blocks are inter
-coded;
3) Early terminate inter-sdp when the best block partitioning is
partition-none

STATS_CHANGED

cpu-use-1 is at commit 6e71b0c is used as anchor.

A1 - 17 frames (0.02% loss with 95.3% run-time)
A2 - 33 frames (0.09% loss with 94.6% run-time)

```
+---------+-------+--------+-------+-------+----------+----------+
| Summary |   Y   |   U    |   V   |  YUV  | Enc-time | Dec-time |
+---------+-------+--------+-------+-------+----------+----------+
| A1      | 0.01% | 0.17%  | 0.11% | 0.02% | 95.3%    | 100%   |
| A2      | 0.07% | 0.14%  | 0.42% | 0.09% | 94.6%    | 100%   |
+---------+-------+--------+-------+-------+----------+----------+
```

Enable winner motion mode.

Based on tid threshold, choose to perform six parameter warp searches in
either winner mode or rough mode.

Tests - cpu-used =1
Anchor:
AOMediaCodec@6e71b0c
Results (RA):

A1 - 17 frames
A2 - 33 frames

```
+---------+--------+--------+--------+--------+----------+----------+
| Summary |   Y    |   U    |   V    |  YUV   | Enc-time | Dec-time |
+---------+--------+--------+--------+--------+----------+----------+
| A1      | -0.01% | 0.02%  | 0.08%  | -0.01% | 98.2%    | 100%     |
| A2      | 0.01%  | -0.07% | -0.01% | 0.01%  | 98.4%    | 101%     |
+---------+--------+--------+--------+--------+----------+----------+
```

…nemv (AOMediaCodec#5134)

Tested on 962f1c4 at speed 1, RA 33 frames

      +------------+-------+-------+-------+-------+-------+
      | Class      |     Y |    Cb |    Cr |  wAvg | Enc%  |
      +------------+-------+-------+-------+-------+-------+
      | A1         | +0.06 | +0.01 | +0.07 | +0.06 | 97.06 |
      | A2         | +0.08 | -0.08 | +0.03 | +0.07 | 96.94 |
      | Avg        | +0.07 | -0.05 | +0.04 | +0.06 | 96.98 |
      +------------+-------+-------+-------+-------+-------+

This has two contributions

Contribution 1

Block size based partition depth reduction for uneven 4 way

Q index threshold is applied only to key frames.

Apply separate partition depth for uneven 4 way partition from H -
partition

Contribution 2

Prune mv using best precision

Do not prune one pel when maximum precision is quarter pel.

Results:
Anchor: 1d2febc

Test: Contribution 1 + Contribution 2

```
+---------+--------+-------+-------+-------+----------+----------+
| Summary |   Y    |   U   |   V   |  YUV  | Enc-time | Dec-time |
+---------+--------+-------+-------+-------+----------+----------+
| A1      | -0.02% | 0.24% | 0.21% | 0.00% | 97.8%    | 100.5%   |
| A2      | 0.10%  | 0.15% | 0.03% | 0.09% | 95.8%    | 99.8%    |
+---------+--------+-------+-------+-------+----------+----------+
```
Test: Contribution 1

```
+---------+--------+-------+--------+--------+----------+----------+
| Summary |   Y    |   U   |   V    |  YUV   | Enc-time | Dec-time |
+---------+--------+-------+--------+--------+----------+----------+
| A1      | -0.02% | 0.05% | -0.14% | -0.02% | 99.0%    | 100.5%   |
| A2      | 0.06%  | 0.09% | 0.19%  | 0.07%  | 97.6%    | 99.3%    |
+---------+--------+-------+--------+--------+----------+----------+

```

This patch refactors av2_model_rd_curvfit() by consolidating two
interp_cubic() calls for computing rate and distortion. Also, the 
relevant SSE2 implementation for the combined interp_cubic()
function along with its corresponding unit test is added. The 
SSE2 implementation achieves ~1.21x speedup compared to the
scalar C version. (adopted from libaom:
https://aomedia-review.googlesource.com/c/aom/+/211441)

Also, unnecessary calls to the function get_dqv() in
update_coeff_general(), update_coeff_simple(), and 
update_coeff_eob() are removed.

Test results (RA)
Anchor: commit 165345b
A1 - 17 frames
A2 - 33 frames

```
--------------------------------------
Speed   Class    Encoder Instruction 
                 Count Reduction (%)
-------------------------------------
  0       A2         0.32
          A1         0.23
-------------------------------------
  1       A2         0.31            
          A1         0.21            
-------------------------------------
  2       A2         0.19            
          A1         0.10            
-------------------------------------
  3       A2         0.26            
          A1         0.11            
-------------------------------------
```

Tweak the speed feature 'restrict_tx_partition_type_search'.

Anchor: 41fc9bf
Test condition: CTC, RA, 33 frames, speed 1

```
+---------+--------+--------+--------+--------+----------+
| Summary |   Y    |   U    |   V    |  YUV   | Enc-time |
+---------+--------+--------+--------+--------+----------+
| A1      |  0.07% |  0.04% |  0.04% |  0.07% | 96.91%   |
| A2      |  0.05% |  0.03% |  0.22% |  0.05% | 96.22%   |
|avg wo b2|  0.06% |  0.04% | -0.02% |  0.06% | 96.24%   |
+---------+--------+--------+--------+--------+----------+

```

STATS_CHANGED

)

Introduce a speed feature for speed >= 1 to
1. Allow only one same reference compound (0,0) and disallow (1,1)
2. Define a priority array for compound reference pairs based on
selection frequency, and only allow the top 2 in the array for all
compound modes other than NEAR_NEARMV and NEAR_NEARMV_OPTFLOW

The macro SAME_REF_COMPOUND_PRUNE in entropymode.h is renamed and moved
to encoder.c because it is only used by the encoder.

RA 33 frames, speed 1
Anchor: 8fbe562

+---------+--------+--------+--------+--------+----------+----------+
| Summary | Y | U | V | YUV | Enc-time | Dec-time |
+---------+--------+--------+--------+--------+----------+----------+
| A1 | +0.01% | +0.06% | -0.05% | +0.01% | 97.9% | 100.0% |
| A2 | +0.04% | +0.00% | +0.35% | +0.04% | 97.4% | 100.6% |
| Avg | +0.03% | +0.02% | +0.23% | +0.03% | 97.6% | 100.4% |
+---------+--------+--------+--------+--------+----------+----------+

This change adds a macro `MAXQ_FOR_GIVEN_BIT_DEPTH()` and replaces the
ternary operators used to compute max-qp using the macro.

No stats changed.

Add a tid based fast method for AMVD under newmv mode.

The results are tested on top of commit 5c29069.

Class A1 and A2 results are llisted below.

```
+---------+--------+--------+--------+--------+----------+
| Summary |   Y    |   U    |   V    |  YUV   | Enc-time |
+---------+--------+--------+--------+--------+----------+
| A1      |  0.07% |  -0.12% |  -0.03% |  0.05% | 98.2%   |
| A2      |  0.06% |  00.14% |  -0.24% |  0.05% | 97.9%   |
+---------+--------+--------+--------+--------+----------+
```
STATS_CHANGED

Skip AMVD modes for NEAR NEWMV, NEW NEARMV, NEAR NEWMV OPFL and NEW
NEARMV OPFL

Skip AMVD modes when tid level is greater than 3

Results:
Anchor: 0d25d58

```
+---------+-------+-------+--------+-------+----------+----------+
| Summary |   Y   |   U   |   V    |  YUV  | Enc-time | Dec-time |
+---------+-------+-------+--------+-------+----------+----------+
| A1      | 0.06% | 0.09% | 0.17%  | 0.07% | 97.6%    | 99.7%    |
| A2      | 0.04% | 0.13% | -0.04% | 0.04% | 97.1%    | 101.3%   |
+---------+-------+-------+--------+-------+----------+----------+
```

Search warp interintra in rough mode when wrl index is greater than or
equal to 2

Search warp interintra in winner mode for remaing wrl indices if warp
interintra is selected in rough mode

Search warp interintra in winner mode for warpmv with mvd flag if warp
interintra is selected in rough mode with warpmv with mvd flag off

Anchor: ef64fa8
Results:

```
+---------+-------+--------+-------+-------+----------+----------+
| Summary |   Y   |   U    |   V   |  YUV  | Enc-time | Dec-time |
+---------+-------+--------+-------+-------+----------+----------+
| A1      | 0.07% | -0.01% | 0.23% | 0.07% | 97.6%    | 100.1%   |
| A2      | 0.05% | -0.03% | 0.28% | 0.06% | 96.8%    | 99.0%    |
+---------+-------+--------+-------+-------+----------+----------+
```

- Abstract distortion calculation into helper function
get_tx_blk_distortion() returning RD_STATS.
- Introduce get_ist_max_set_id() and get_ist_set_id() helper functions.
- Improve readability of prune_rectangular_tx_type() by removing
redundant tx_mask_32[][] lookup table.
- Eliminate redundant call to av2_get_ext_tx_set_type() in
search_tx_type() by reusing txfm_param.tx_set_type.
- Add early loop exit for FSC mode when transform dimensions exceed
FSC_MAXWIDTH / FSC_MAXHEIGHT on luma plane.

No stats changed.

* MLP intra mode pruning

Replace HOG-based directional mode pruning with an MLP that predicts the
top-5 most likely luma intra base modes per block. The 4-layer network
(104->128->64->32->13) takes an 8x8 downsampled source patch, neighbor
modes, QP, block size, and a 32-bin HOG histogram as inputs. Active in
both all-intra (AI) and inter (RA/LD) frames; falls back to HOG for 4x4,
4x8, and 8x4 blocks. Enabled at speed >= 1 via
sf.intra_sf.intra_pruning_with_mlp.

Anchor: commit b4e5915
Performance of this change in isolation, Speed 1 (cpu-used=1), FG16 CTC
(33 frames):

AI:
```
+------------+-------+-------+-------+-------+---------+---------+
| Class      |     Y |    Cb |    Cr |  wAvg | EncWall | DecWall |
+------------+-------+-------+-------+-------+---------+---------+
| A1         |  0.14 |  0.05 | -0.02 |  0.13 |      91 |     101 |
| A2         |  0.17 |  0.06 | -0.03 |  0.15 |      90 |      99 |
+------------+-------+-------+-------+-------+---------+---------+
| Avg w/o B2 |  0.17 | -0.02 |  0.07 |  0.16 |      90 |     101 |
+------------+-------+-------+-------+-------+---------+---------+
```

RA:
```
+------------+-------+-------+-------+-------+---------+---------+
| Class      |     Y |    Cb |    Cr |  wAvg | EncWall | DecWall |
+------------+-------+-------+-------+-------+---------+---------+
| A1         |  0.13 |  0.17 | -0.58 |  0.09 |      97 |     100 |
| A2         |  0.11 |  0.04 |  0.05 |  0.10 |      96 |     100 |
+------------+-------+-------+-------+-------+---------+---------+
| Avg w/o B2 |  0.03 |  0.03 | -0.32 |  0.01 |      96 |     100 |
+------------+-------+-------+-------+-------+---------+---------+
```

STATS_CHANGED

- partition_allowed_*, prune_partition_* fields are grouped into one
array and made accessible via partition_type

No stats changed

Change-Id: I9983d117e36805b9c936038cdcdbd22c2fc23413

This patch avoids extra stack buffer size for `process_ref`
structure and uses the correct size `MFMV_STACK_SIZE` in
`av2_setup_motion_field()`. This aligns with the maximum
allowed size check in `check_and_add_process_ref()`.

This patch refactors `check_and_add_process_ref()` by removing
`checked_count` and its associated code as `process_count`
serves the same purpose.

Initially, `ProcessRefTMVP->type` was introduced to indicate whether
to use side projection (type 0) or target frame projection (type 1).
Later, the logic was simplified and type 0 is only used for every
case.

As a result, `motion_field_projection_start_target()` is entirely
unused. This patch cleans up these unused code.

The recent removal of `motion_field_projection_start_target()` causes
GCC compiler to inline `motion_field_projection_side()` into
`av2_setup_motion_field()`, increasing the decoder instruction count
by ~0.5%. Marking the function noinline prevents this issue.

Clang compiler shows neutral impact for this change.

Introduce 3 EOB levels adaptive tx search pruning.
eob_level = 0: eob >= max_eob / 4
eob_level = 1: max_eob / 12 <= eob < max_eob / 4
eob_level = 2: eob < max_eob / 12

Anchor:
AOMediaCodec@0d25d58
Tests: cpu-used =1, RA
A1 - 17 frames
A2 - 33 frames

```
+---------+--------+--------+--------+--------+----------+----------+
| Summary |   Y    |   U    |   V    |  YUV   | Enc-time | Dec-time |
+---------+--------+--------+--------+--------+----------+----------+
| A1      |  0.09% | -0.06% | -0.99% |  0.03% | 96.4%    | 99.5%    |
| A2      |  0.09% | -0.35% | -0.20% |  0.06% | 97.7%    | 99.6%    |
+---------+--------+--------+--------+--------+----------+----------+
```

Make the C and AVX2 code have the same behavior. Add unit test to check
the two match.

MLP-based partition pre-screener
    
Add an MLP-based partition mode pre-screener for the encoder's partition
search. A small 3-layer network (38 inputs, hidden dims 64/32, 4
outputs) predicts NONE/HORZ/VERT/SPLIT per block from a 32-bin HOG
histogram over the source luma plane plus 6 scalar features (source
variance, block size, QP, RD cost of the NONE partition, and the winning
partition type of the above/left neighbors). Separate models are trained
for intra-only and inter frames. When the model confidently predicts
NONE, the weaker of the HORZ/VERT rectangular directions is pruned from
the RD search. Enabled at speed >= 1 via
sf.part_sf.partition_pruning_with_mlp.

Anchor: commit 1d2febc
Performance of this change in isolation, Speed 1 (cpu-used=1), FG16 CTC
(33 frames):

AI:
```
+------------+------+-------+-------+------+------+
| Class      |    Y |    Cb |    Cr | wAvg | Enc% |
+------------+------+-------+-------+------+------+
| A1         | 0.14 |  0.05 | -0.01 | 0.13 |   90 |
| A2         | 0.17 |  0.05 | -0.02 | 0.16 |   90 |
+------------+------+-------+-------+------+------+
| Avg w/o B2 | 0.17 | -0.02 |  0.08 | 0.16 |   90 |
+------------+------+-------+-------+------+------+
```

RA:
```
+------------+------+------+-------+------+------+
| Class      |    Y |   Cb |    Cr | wAvg | Enc% |
+------------+------+------+-------+------+------+
| A1         | 0.12 | 0.23 | -0.40 | 0.10 |   96 |
| A2         | 0.07 | 0.24 |  0.36 | 0.08 |   95 |
+------------+------+------+-------+------+------+
| Avg w/o B2 | 0.13 | 0.42 | -0.09 | 0.12 |   95 |
+------------+------+------+-------+------+------+
```

STATS_CHANGED

This change reduces duplicate code in functions that recurse through pc
trees. No stats changed

Anchor: 6d405a3

Test condition: CTC, RA, 33 frames, speed 1

+---------+--------+--------+--------+--------+----------+
| Summary |   Y    |   U    |   V    |  YUV   | Enc-time |
+---------+--------+--------+--------+--------+----------+
| A1      |  0.01% | -0.03% |  0.08% |  0.01% | 99.14%   |
| A2      |  0.02% |  0.05% |  0.03% |  0.02% | 97.98%   |
|avg wo b2|  0.02% |  0.04% |  0.04% |  0.02% | 97.69%   |
+---------+--------+--------+--------+--------+----------+

STATS_CHANGED

Introduced an encoder option: "enable_low_complexity_decode" (LC mode)
to target reduced decoding complexity. This mode is disabled by default.
Also added related API control for ongoing LC mode development.

1. Cleanup the unused sf 'enable_interinter_diffwtd_newmv_search` and its
associated code
2. Cleanup the code and comments related to COMPOUND_DISTWTD

No Stats Changed

This feature considers the distortion reduction of deblocking filter for
partition research.

-- The deblocking filter is applied to a non-split partition after the
best mode is picked for the current block. The distortion improvement of
the deblocking filter is used to update the best RD cost of the current
none-split partition block.

This encoder side only feature provides the coding gain with slight
encoding time increase. Should be a good trade-off for low speed level.

Results of 33 frame (cpu1), a1 (missing 3 sequences) and a2 (missing 1
sequence) are as follows:

+---------+--------+-------+-------+-------+----------+----------+
| Summary | Y | U | V | YUV | Enc-time | Dec-time |
+---------+--------+-------+-------+-------+----------+----------+
| A1  | -0.62% |  -0.14% | -0.49% | -0.58% | 102.06% | 100.82% |
| A2 | -0.39% | +0.15% | -0.70% | -0.38% | 102.37% | 100.56% |
+---------+--------+-------+-------+-------+----------+----------+