Adjust speed features for RTC speed >= 6.

[marpan-max]

Set tx_size_search_level = USE_FAST_RD, and add level 3 to restrict_tx_partition_type_search to only test
TX_PARTITION_NONE and TX_PARTITION_SPLIT.

Also switch cdef_pick_method to CDEF_FAST_SEARCH_LVL3, until the CDEF_PICK_FROM_Q model is further evaluated/improved.

Only affects realtime mode speed >= 6.

This brings back some quality with small speed loss: on average over rtc set of vga and 720p clips, ~10% bdrate gain with ~4% encoder speed slowdown. This is with the command line settings below with the qp range {70 80 90 100 110 120 130 150 170}:

--passes=1 --bit-depth=8 --obu --lag-in-frames=0 --kf-min-dist=1000 --kf-max-dist=1000 --auto-alt-ref=0 --enable-tpl-model=0 --enable-keyframe-filtering=0 --enable-deblocking=1 --enable-restoration=0 --enable-intra-edge-filter=0 --enable-flip-idtx=1 --enable-masked-comp=0 --enable-onesided-comp=0 --enable-interintra-comp=0 --enable-smooth-interintra=0 --enable-diff-wtd-comp=0 --enable-interinter-wedge=0 --enable-interintra-wedge=0 --enable-global-motion=0 --enable-warped-motion=0 --enable-smooth-intra=0 --enable-paeth-intra=0 --enable-cfl-intra=0 --force-video-mode=1 --enable-overlay=0 --enable-angle-delta=0 --enable-trellis-quant=0 --enable-qm=0 --use-intra-dct-only=1 --coeff-cost-upd-freq=2 --mode-cost-upd-freq=2 --mv-cost-upd-freq=3 --frame-parallel=0 --aq-mode=0 --deltaq-mode=0 --frame-boost=0 --noise-sensitivity=0 --cdf-update-mode=1 --reduced-reference-set=1 --enable-ref-frame-mvs=0 --erp-pruning-level=0 --use-ml-erp-pruning=0 --enable-ext-partitions=0 --enable-mrls=0 --enable-pc-wiener=0 --enable-wiener-nonsep=0 --enable-tip=0 --enable-bawp=0 --enable-cwp=0 --enable-imp-msk-bld=0 --enable-ist=0 --enable-inter-ist=0 --enable-inter-ddt=0 --enable-cctx=0 --enable-ibp=0 --max-drl-refmvs=0 --max-drl-refbvs=0 --enable-refmvbank=0 --enable-opfl-refine=0 --enable-ccso=0 --enable-lf-sub-pu=0 --enable-adaptive-mvd=0 --enable-flex-mvres=0 --enable-joint-mvd=0 --enable-refinemv=0 --enable-mvd-sign-derive=0 --enable-parity-hiding=0 --enable-warp-delta=0 --enable-warp-extend=0 --tile-columns=0 --gf-min-pyr-height=0 --gf-max-pyr-height=0 --end-usage=q --use-fixed-qp-offsets=0 --psnr --threads=1 --enable-sdp=0 --min-gf-interval=8 --max-gf-interval=8 --explicit-ref-frame-map=0 --enable-bru=0 --enable-ext-seg=0 --enable-six-param-warp-delta=0 --enable-cdef=1 --enable-cdef-on-skip-txfm=0 --dpb-size=8 --use-inter-dct-only=0 --enable-fsc=1 --enable-idtx-intra=1 --enable-palette=1 --enable-intrabc-ext=0 --enable-intrabc=0 --tune-content=0 --rt --cpu-used=6 --enable-gdf=0 --max-reference-frames=3 --max-q=qp ---min-q=qp

[urvangjoshi]

Also switch cdef_pick_method to CDEF_FAST_SEARCH_LVL3, until the CDEF_PICK_FROM_Q model is further evaluated/improved.

@marpan-max
Optional suggestion (as this seems like a temporary change):

Note that @chengchen-google found CDEF_FAST_SEARCH_LVL3 method to not work well: 7c9dfba

I also independently found that CDEF_FAST_SEARCH_LVL2 doesn't work well. I believe CDEF_FAST_SEARCH_LVL1 is the one used for speed >= 2 currently -- so maybe better to use that.

[marpan-max]

Also switch cdef_pick_method to CDEF_FAST_SEARCH_LVL3, until the CDEF_PICK_FROM_Q model is further evaluated/improved.

@marpan-max Optional suggestion (as this seems like a temporary change):

Note that @chengchen-google found CDEF_FAST_SEARCH_LVL3 method to not work well: 7c9dfba

I also independently found that CDEF_FAST_SEARCH_LVL2 doesn't work well. I believe CDEF_FAST_SEARCH_LVL1 is the one used for speed >= 2 currently -- so maybe better to use that.

Thanks, for now prefer to keep it at L3 for rtc.