The br_cdf and lps_cdf with a new 4-state symbol br_cdf.
The br symbol indicates whether the level is k, k+1, k+2 or >k+2
In the latter case, a new br symbol is read. Up to 4 br symbols are
read which will reach level 14 at most. Levels greater than 14 are
golomb coded.

The adapted symbol count is reduced further by this commit.
E.g. for the I-frame of ducks_take_off at cq=12, the number of adapted symbols
is reduced from 4.27M to 3.85M. About 10% reduction.

Gains seems about neutral on a limitied subset.

Change-Id: I294234dbd63fb0fa26aef297a371cba80bd67383

This experiment modifies lv_map to make use of multi symbol.

Replace the nz_map and coeff_base binary CDF with a new multi-symbol
CDF of size 4. The new base_cdf indicates for each coeff if the level
is 0, 1, 2 or >2. Two new special contexts are added to be used for the
last coefficient (the EOB coeff). For the EOB coefficient we already know
that it is non-zero. We use one context for DC EOB and one for AC EOB
(this can potentially be refined more).

The new symbol is read/written by special bitreader/bitwriter functions.
Those functions reduce the probability precision from 15bit to 9bit before
the invocation of the arithmetic coding engine.

The adapted symbol count is significantly reduced by this experiment.
E.g. for the I-frame of ducks_take_off at cq=12, the number of adapted symbols
is reduced from 6.7M to 4.3M.

Change-Id: Ifc3927d81ad044fb9b0733f1e54d713cb71a1572

Include a few RDO fixes that properly account for the extra flag
cost at the right place. Also entropy coding of the flag is made
contexted on tx_size and based on cdf framework.

Change-Id: I52f98ace7e253ccc08917a4a7b517515d1d58a98

Make it work with NO_FRAME_CONTEXT_SIGNALING.

Change-Id: I27813305c68de7042678706c1c9b938b172c3666

Conveys depth from the largest transform size instead of the
actual transform size. Besides, the max depth is now limited
by the macro MAX_TX_DPETH set at 2.

Results: BDRATE lowres (30 frames): -0.005%

Change-Id: I1ccbac8ee18c77b816a6a8f500abfaa7892b21de

Support cdf for jnt_comp read/write.

Change-Id: I2c29277a8b06b3e9f571355946b70ce0d492fbb2

Tested on screen_content, it has very little impact on compression quality.

Change-Id: I49c7d5e8de8420c0d2af1b327c084a2667cfea40

This experiment has been abandonned for AV1.

Change-Id: I18cf1354df928a0614a1e58b718cd96ee7999925

Development of this experiment will be deferred to AV2.

Change-Id: I3c4615a21b59508500bed8aab0a5c54413b4f284

The "use_intrabc" flag is signaled with CDF. No need to keep a counter
for it.

Change-Id: Ia62ef8f264aa5ce2f6fceddc0b2a7d2032c73044

This experiment has been adopted, we can simplify the code
by dropping the associated preprocessor conditionals.

Change-Id: I02ed47186bbc32400ee9bfadda17659d859c0ef7

This name better reflects the functionality of the mode.

Change-Id: Idc2372e7c7b226f70f63fa4f272a88cb4d857089

Change-Id: Icbedc16b01adf9b48f0f357ec89143462865d54e

At the frame header level, add the checking on whether an inter-coded
frame allows the use of 'skip_mode'. At the block level, add the
decoding of 'skip_mode' for all the blocks if 'skip_mode' is allowed
for the current frame. If 'skip_mode' is set, no further bit needs to
read out, and the block is set as:
- Inter-coded in compound mode;
- With the nearest forward and backward reference frames;
- In NEAREST_NEARESTMV mode;
- In SIMPLE_TRANSLATION motion mode;
- In COMPOUND_AVERAGE compound type; and
- Skip set for residual.

Change-Id: I50297f63a81135109332c4a51b516bffd7726777

This experiment has been adopted, we can simplify the code
by dropping the associated preprocessor conditionals.

Change-Id: I54fee8a18afaec5333ae852eb6bd9ac0e2550db1

This experiment has been adopted, we can simplify the code
by dropping the associated preprocessor conditionals.

Change-Id: I2dce80e1e1b2116708b6ba9feeacaacc12af8fc4

Change-Id: I39cfbb135add0553cadf64481b13786831fbdddd

Change-Id: I0cc53a03f07a11a6f7ea0570ff4ee8cf7c18c5aa

For ext-intra direcation intra modes:

1. Use neighbor block modes to modify edge filtering strength
   Coding gain (lowres/midres/hdres):
     (8 keyframes)
     PSNR: -0.19 -0.22 -0.10
     SSIM: -0.29 -0.27 -0.13

2. Use context-based cdf to code angle_delta syntax
     (8 keyframes)
     PSNR: -0.20 -0.24 -0.27
     SSIM: -0.29 -0.33 -0.37

3. Filter corner sample:
     (8 keyframes)
     PSNR: -0.01 -0.02 -0.05
     SSIM: -0.03 -0.04 -0.05

Combined Bd-rate improvement for 8 keyframes
     PSNR: -0.40 -0.47 -0.40
     SSIM: -0.57 -0.60 -0.51

Change-Id: Id47ac17b6bf91cd810b70cacfc5b457341f417f3

Change-Id: I0e6f7ab981e31f7120105515f6204568b6dc82d3

Change-Id: Ib36a8df1a3ebddbf4320fb7b9b5537041bddc3a3

Use br-node approach, which can be easily turned into multi-symbol
if desired.

Change-Id: I40df5178ab299af24d347d91f01a88dbfc9305a6

Change-Id: I2ae2a33574bc3072561e696a31e0ea2e0770afa9

Change-Id: If77800c0904b5e004508274acb32ae46a641405b

Change-Id: Id955e62c89b44781cef6b562fbc1e5782fccf95e

Change-Id: Id228c94fbe6005ac37a59bb8c23cfb0f95f97af0

Change-Id: Ic8670dcfed8efa37050816bbb8062f9092886ef7

Change-Id: Ia67beabb85eedd5da5eb69f434dde71f66f08006

This experiment has been adopted.

Change-Id: Ife4c18a59791268b7ac0de5a8a08e762a042cae2

Change-Id: Id377c68e30031ad4697ca1ba311487b803a8af4c

Change-Id: I262d9b538988ddcbcac13a217c786fa5df17f8a4

Change-Id: I5bff0a68602a89ce480fec049c8b2c4bce44f6bb

Change-Id: I9d3f0380865790d8adcb85f03305b193bc1949d7

This experiment has been adopted, we can simplify the code
by dropping the associated preprocessor conditionals.

Change-Id: I4705652ac8231ee25f960e8096dc97c2aeed1d20

This experiment uses switchable interpolation filter for intra
prediction. Current gain is too small to be useful for AV1.
May explore more for AV2 in the future.

Change-Id: I24ae8c75dc71adf6271eabdb68a81b68a0869fa2

BUG=aomedia:907

Change-Id: I30a0290e499d338250343b5f9092bdcabe7d867a

Make fi mode index entropy coded instead of using raw bits. Mode
cost estimation in key-frame RDO is updated as well. Modification
to inter frame RDO is not included in this patch.
Also key-frame y mode cdf table is re-trained since fi modes are
attached to DC_PRED

Key frame BDRate:
-0.399% lowres, -0.339% midres

Change-Id: I9ccf478b0a2e48fb1870fe8451e45e2c858a5f63

Count filter level reuse, sign, and delta. And use counts to train
default cdfs.
Default cdf tables updated.

Change-Id: If4fbf3e06ec7d568d940ca7b170bbbb4b778f176

Change-Id: Ic4c5cb2baa661733662cdf932a05dc6de1667b6b

In this experiment, sharp image discontinuity in the predicted
block is detected. Based on this discontinuity, we choose
particular LGTs as row and column transforms.

Bitstream syntax, entropy coding, and RD search for LGT are added.
One binary symbol is used to signal whether LGT is used. This
experiment can work independently with the lgt experiment.

lowres: -0.414% for key frames, -0.151% overall
midres: -0.413% for key frames, -0.161% overall

Change-Id: Iaa2f2c2839c34ca4134fa55e77870dc3f1fa879f