This commit allows the rate-distortion optimization recursion
at encoder to go down to 4x4 block size. It deprecates the use
of I4X4_PRED and SPLITMV syntax elements from bit-stream
writing/reading. Will remove the unused probability models in
the next patch.

The partition type search and bit-stream are now capable of
supporting the rectangular partition of 8x8 block, i.e., 8x4
and 4x8. Need to revise the rate-distortion parts to get these
two partition tested in the rd loop.

Change-Id: I0dfe3b90a1507ad6138db10cc58e6e237a06a9d6

This reverts commit a9333111

Change-Id: I2321f88011178381adbcffeda1bcc6a430ab8f1d

To be consistent with other prediciton modes

Change-Id: If9e1464e5c807f0b36047a046c4ac59d91b1b868

Change-Id: Ib19352e391408507f2237985501406900a355964

Change-Id: Ib7448f7f325ba34a3cba8ab3129028e31e593cf5

Change-Id: I493bcf7bac930e9937a9b57e4b7c803da22728bd

Change-Id: Ia7a772718a4b11b413c36d4280df8668e19c9084

Change-Id: Id1cc1c2663b9c2219cb830ffb4b0c6ab3468dc04

Allow motion search multiple times iteratively, and break out
the loop if this search couldn't find better motion vectors.
Limit the maximum number of search to 2.

Tests results:
1. stdhd set: 0.311%(overall psnr); 0.346%(ssim).
positive gain on 10 out of 16 clips(best: 2.746% on sunflower;
worst: -0.434% on old_town_cross).
2. derf set: 0.016%(overall psnr); 0.062%(ssim).
positive gain on half of the clips(best: 0.499% on bowing;
worst: -0.387 on city).

Change-Id: Ibf0a51776d4caf7707be0586346db08128117559

Change band calculation back to simpler model based
on the order in which coefficients are coded in scan order
not the absolute coefficient positions.

With the scatter scan experiment enabled the results were
appear broadly neutral on derf (-0.028) but up a little on std-hd +0.134).

Without the scatterscan experiment on the results were up derf as well.

Change-Id: Ie9ef03ce42a6b24b849a4bebe950d4a5dffa6791

Move set_partition_seg_context_ to common file. Use consistent
context setup conditions for partition probability model update at
encoder and decoder.

Change-Id: I24b7ed3b1c48e3d2568191a46b70136b99b67b1a

Use 4x4 block coding for UV components arbitrarily in I4X4_PRED and
SPLITMV coding modes. This is a temporary solution to enable
bit-stream support for recursive partition down to 4x4 block size.
Will separate the functionalities of 4x4 block coding rate-distortion
out from those of superblocks.

Change-Id: I03dc15d5897014f175f3f2c91e9b266091d56797

Use common function to fetch/assign sb_index in rd loop, bit-stream
writing and reading.

Change-Id: I1d8a214a57ed9cbcd026040436ef33e5e39d65b7

Change-Id: Ic11dc052fb641687c015e1bbc37181b9babcd43e

mdcounts seems no longer used.

Change-Id: Idd8162e8acfa3f5be7a18767156cc79ccbc2bdee

In current code, motion vectors got from single prediction mode are used
in compound prediction mode directly. These motion vectors may not give
accurate prediction since they are searched independently. In this patch,
we took Pascal's suggestion, and did joint motion search in compound
prediction mode to find better motion vectors in this situation.
Test results:
Overall PSNR: 0.570%(derf), 0.918%(stdhd);
SSIM: 0.572%(derf), 1.009%(stdhd);

The encoder is a little slower. This can be improved since some c
code is used in motion search.

Change-Id: Ib30c9240f6c56c9b070867b4ca89412a76d9f3c6

This commit enables the search for the optimal superblock
partition types in the recursion form. The intention is to
make the optimization process more concise and ready to
support partition down to 4x4 block size next.

Change-Id: Iae279a67df3a7cc372553c84c775bc4d2f3e4336

Use value already computed value to save of calls

Change-Id: I42836698e59c116416ccd75395bebdd11dd609fb

Increase the allocated size of the token array to support 4:4:4.

Change-Id: I7766a7bedc74b819dcc1f3622d634f340fd3186d

The previous code was somewhat vestigial for 16x16 MI units, but was
incorrect when called with chroma blocks larger than 4x4 because the
block index caused a reference to a non-existent BMI. This patch uses
the same MV for all chroma subblocks in SPLITMV mode, which is
suboptimal for non-4:2:0 subsamplings, but as SPLITMV may be removed
in the near future, will use this as a stop gap.

Change-Id: I3211cee5ccf1cfb426e5eef5353b0ce5bb92b4cd

Fixes some debugging code to be able to write out frames with
chroma other than 4:2:0.

Change-Id: I5ee3d29e584db1f52d2de344db249e927eff10b7