fix a buffer overread in x264_mbtree_propagate_cost_sse2. no effect on actual behavior, only theoretical correctness.
fix x264_slicetype_frame_cost_recalculate on I-frames, which previously used all 0 mb costs.
shut up a valgrind warning in predict_8x8_filter_mmx.

1.6x faster on conroe.

AQ was applied inconsistently, with some AQed costs compared to other non-AQed costs. Strangely enough, fixing this increases SSIM on some sources but decreases it on others. More investigation needed.
Account for weighted bipred.
Reduce memory, increase precision, simplify, and early terminate.

Eliminates a memory leak.

Fuzz tests show that all mallocs appear to be checked correctly now.

ftell doesn't seem to work properly on Windows in text mode.

Delay frames for threading don't actually count as part of lookahead.

Apparently some people are actually *using* placebo, so I've added this preset to bridge the gap.

On by default; can be turned off with --no-mbtree.
Uses a large lookahead to track temporal propagation of data and weight quality accordingly.
Requires a very large separate statsfile (2 bytes per macroblock) in multi-pass mode.
Doesn't work with b-pyramid yet.
Note that MB-tree inherently measures quality different from the standard qcomp method, so bitrates produced by CRF may change somewhat.
This makes the "medium" preset a bit slower.  Accordingly, make "fast" slower as well, and introduce a new preset "faster" between "fast" and "veryfast".
All presets "fast" and above will have MB-tree on.
Add a new option, --rc-lookahead, to control the distance MB tree looks ahead to perform propagation analysis.
Default is 40; larger values will be slower and require more memory but give more accurate results.
This value will be used in the future to control ratecontrol lookahead (VBV).
Add a new option, --no-psy, to disable all psy optimizations that don't improve PSNR or SSIM.
This disables psy-RD/trellis, but also other more subtle internal psy optimizations that can't be controlled directly via external parameters.
Quality improvement from MB-tree is about 2-70% depending on content.
Strength of MB-tree adjustments can be tweaked using qcompress; higher values mean lower MB-tree strength.
Note that MB-tree may perform slightly suboptimally on fades; this will be fixed by weighted prediction, which is coming soon.

Make predictors have an offset in addition to a multiplier.
This primarily fixes issues in sources with lots of extremely static scenes, such as anime and CGI.
We tried linear regressions, but they were very unreliable as predictors.
Also allow VBV to be slightly more aggressive in raising QPs to avoid not having enough bits left in some situations.
Up to 1db improvement on some clips.

An entry in subpel_iterations was missing.
I have no idea how QPRD was working at all without this change.

Deal with some out-of-date information.

re-roll a loop (saves 44KB code size, which is the cause of most of this speed gain)
don't re-mc mvs that haven't changed

Cache chroma MC during refine_bidir_rd and use both the luma and chroma caches to skip MC in macroblock_encode.
Fix incorrect call to rd_cost_part; refine_bidir_rd output was incorrect for i8>0.
Remove some redundant clips.
~12% faster refine_bidir_rd.

It does what it says it does.

fprofile settings now actually fprofile QPRD.
Don't use i_mbrd before initializing it.

Trellis used wrong lambda with trellis=1

Also add a few more checks to eliminate the need for spel_border.

Refactor trellis lambda selection to be done in analyse_init instead of in trellis.
This will allow for more easy adaption of lambda later on; for now it allows constant lambda across variable QPs.
QPRD is only available with adaptive quantization enabled and generally improves SSIM and visual quality.
Additionally, weight the SSD values from RD based on the relative QP offset for chroma; helps visually at high QPs where chroma has a lower QP than luma.
This fixes some visual artifacts created by QPRD at high QPs.
Note that this generally hurts PSNR and SSIM, and so is only on when psy-RD is on.

Palignr-based solution for the most commonly used qpel function.
1-1.5% faster overall on Core 2 chips.

"Auto-variance" uses log(var)^2 instead of log(var) and attempts to adapt strength per-frame.
Generates significantly better SSIM; on by default with --tune ssim.
Whether it generates visually better quality is still up for debate.
Available as --aq-mode 2.

~70% faster chroma MC on 32-bit Conroe
Also slightly faster SSSE3 intra_sad_8x8c

Faster lossless, cleaner code.
SSSE3 version of zigzag_sub_4x4_field, faster lossless interlaced coding.

For some types of input file, x264 did the adjustment before width/height were known.

Also add b-adapt 2 to fprofile.

Eliminate some redundant shifts.

Other new features include "tune" and "profile" settings; see --help for more details.
Unlike most other settings, "preset" and "tune" act before all other options.
However, "profile" acts afterwards, overriding all other options.
Our defaults have also changed: new defaults are --subme 7 --bframes 3 --8x8dct --no-psnr --no-ssim --threads auto --ref 3 --mixed-refs --trellis 1 --weightb --crf 23 --progress.
Users will hopefully find these changes to greatly improve usability.

Faster chroma encoding by terminating early if heuristics indicate that the block will be DC-only.
This works because the vast majority of inter chroma blocks have no coefficients at all, and those that do are almost always DC-only.
Add two new helper DSP functions for this: dct_dc_8x8 and var2_8x8.  mmx/sse2/ssse3 versions of each.
Early termination is disabled at very low QPs due to it not being useful there.
Performance increase is ~1-2% without trellis, up to 5-6% with trellis=2.
Increase is greater with lower bitrates.

frame_init_lowres_core check didn't check the C plane.
However, all x86 and PPC assembly was correct regardless of the unit test being incorrect.

Improves sub-p8x8 mode decision.

Also clean up a lot of pointless code duplication in CAVLC MV coding.

Faster CABAC CBF context calculation for inter blocks.
Add x264_constant_p(), will probably be useful in the future as well.
Simpler subpartition functions.
Clean up and optimize mvd_cpn a bit more.
Various other minor optimizations.

Faster CABAC mvd coding.