Added comments to make the codebase build cleanly in Doxygen.

Change-Id: I01e000ceac57dbafa04342858c8f1be250ba20d1

Restore ABI compatibility with the master branch.

Change-Id: Ie9f6fdf536662bd87dfcf114d16f003422670763

This patch adds column-based tiling. The idea is to make each tile
independently decodable (after reading the common frame header) and
also independendly encodable (minus within-frame cost adjustments in
the RD loop) to speed-up hardware & software en/decoders if they used
multi-threading. Column-based tiling has the added advantage (over
other tiling methods) that it minimizes realtime use-case latency,
since all threads can start encoding data as soon as the first SB-row
worth of data is available to the encoder.

There is some test code that does random tile ordering in the decoder,
to confirm that each tile is indeed independently decodable from other
tiles in the same frame. At tile edges, all contexts assume default
values (i.e. 0, 0 motion vector, no coefficients, DC intra4x4 mode),
and motion vector search and ordering do not cross tiles in the same
frame.
t log

Tile independence is not maintained between frames ATM, i.e. tile 0 of
frame 1 is free to use motion vectors that point into any tile of frame
0. We support 1 (i.e. no tiling), 2 or 4 column-tiles.

The loopfilter crosses tile boundaries. I discussed this briefly with Aki
and he says that's OK. An in-loop loopfilter would need to do some sync
between tile threads, but that shouldn't be a big issue.

Resuls: with tiling disabled, we go up slightly because of improved edge
use in the intra4x4 prediction. With 2 tiles, we lose about ~1% on derf,
~0.35% on HD and ~0.55% on STD/HD. With 4 tiles, we lose another ~1.5%
on derf ~0.77% on HD and ~0.85% on STD/HD. Most of this loss is
concentrated in the low-bitrate end of clips, and most of it is because
of the loss of edges at tile boundaries and the resulting loss of intra
predictors.

TODO:
- more tiles (perhaps allow row-based tiling also, and max. 8 tiles)?
- maybe optionally (for EC purposes), motion vectors themselves
  should not cross tile edges, or we should emulate such borders as
  if they were off-frame, to limit error propagation to within one
  tile only. This doesn't have to be the default behaviour but could
  be an optional bitstream flag.

Change-Id: I5951c3a0742a767b20bc9fb5af685d9892c2c96f

Started adding support for multiple internal decoder instances.  Also added
code to limit the vp8 config options available when using frame-based
multithreading.

Change-Id: I0f1ee7abcfcff59204f50162e28254b8dd6972eb

Change-Id: I44b3ad780cef6f448fa17ff8e28fea87ef9cd518

Approximate the Google style guide[1] so that that there's a written
document to follow and tools to check compliance[2].

[1]: http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml
[2]: http://google-styleguide.googlecode.com/svn/trunk/cpplint/cpplint.py

Change-Id: Idf40e3d8dddcc72150f6af127b13e5dab838685f

Avoid a pthreads dependency via pthread_once() when compiled with
--disable-multithread.

In addition, this synchronization is disabled for Win32 as well, even
though we can be sure that the required primatives exist, so that the
requirements on the application when built with --disable-multithread
are consistent across platforms.

Users using libvpx built with --disable-multithread in a multithreaded
context should provide their own synchronization. Updated the
documentation to vpx_codec_enc_init_ver() and vpx_codec_dec_init_ver()
to note this requirement. Moved the RTCD initialization call to match
this description, as previously it didn't happen until the first
frame.

Change-Id: Id576f6bce2758362188278d3085051c218a56d4a

Remove a bunch of compatibility code dating back to before the initial
libvpx release.

Change-Id: Ie50b81e7d665955bec3d692cd6521c9583e85ca3

doxygen < 1.7.? seems to have been more tolerant of single line
\if/\endif

This change fixes warnings such as:
mainpage.dox:13: warning: unable to resolve reference to `vp8_encoder-'
for \ref command
vpx_decoder.h:193: warning: explicit link request to 'n' could not be
resolved

Change-Id: If3d04af5ede1b0d1e2c63021d0e4ac8f98db20b2

This is a code snapshot of experimental work currently ongoing for a
next-generation codec.

The codebase has been cut down considerably from the libvpx baseline.
For example, we are currently only supporting VBR 2-pass rate control
and have removed most of the code relating to coding speed, threading,
error resilience, partitions and various other features.  This is in
part to make the codebase easier to work on and experiment with, but
also because we want to have an open discussion about how the bitstream
will be structured and partitioned and not have that conversation
constrained by past work.

Our basic working pattern has been to initially encapsulate experiments
using configure options linked to #IF CONFIG_XXX statements in the
code. Once experiments have matured and we are reasonably happy that
they give benefit and can be merged without breaking other experiments,
we remove the conditional compile statements and merge them in.

Current changes include:
* Temporal coding experiment for segments (though still only 4 max, it
  will likely be increased).
* Segment feature experiment - to allow various bits of information to
  be coded at the segment level. Features tested so far include mode
  and reference frame information, limiting end of block offset and
  transform size, alongside Q and loop filter parameters, but this set
  is very fluid.
* Support for 8x8 transform - 8x8 dct with 2nd order 2x2 haar is used
  in MBs using 16x16 prediction modes within inter frames.
* Compound prediction (combination of signals from existing predictors
  to create a new predictor).
* 8 tap interpolation filters and 1/8th pel motion vectors.
* Loop filter modifications.
* Various entropy modifications and changes to how entropy contexts and
  updates are handled.
* Extended quantizer range matched to transform precision improvements.

There are also ongoing further experiments that we hope to merge in the
near future: For example, coding of motion and other aspects of the
prediction signal to better support larger image formats, use of larger
block sizes (e.g. 32x32 and up) and lossless non-transform based coding
options (especially for key frames). It is our hope that we will be
able to make regular updates and we will warmly welcome community
contributions.

Please be warned that, at this stage, the codebase is currently slower
than VP8 stable branch as most new code has not been optimized, and
even the 'C' has been deliberately written to be simple and obvious,
not fast.

The following graphs have the initial test results, numbers in the
tables measure the compression improvement in terms of percentage. The
build has  the following optional experiments configured:
--enable-experimental --enable-enhanced_interp --enable-uvintra
--enable-high_precision_mv --enable-sixteenth_subpel_uv

CIF Size clips:
http://getwebm.org/tmp/cif/
HD size clips:
http://getwebm.org/tmp/hd/
(stable_20120309 represents encoding results of WebM master branch
build as of commit#7a159071)

They were encoded using the following encode parameters:
--good --cpu-used=0 -t 0 --lag-in-frames=25 --min-q=0 --max-q=63
--end-usage=0 --auto-alt-ref=1 -p 2 --pass=2 --kf-max-dist=9999
--kf-min-dist=0 --drop-frame=0 --static-thresh=0 --bias-pct=50
--minsection-pct=0 --maxsection-pct=800 --sharpness=0
--arnr-maxframes=7 --arnr-strength=3(for HD,6 for CIF)
--arnr-type=3

Change-Id: I5c62ed09cfff5815a2bb34e7820d6a810c23183c

Remove error concealment code.

Change-Id: I882705174fbfea212e96f7f684e47a671dbe5c67

Adding support for several partitions within one input fragment.
This is necessary to fully support all possible packetization
combinations in the VP8 RTP profile. Several partitions can
be transmitted in the same packet, and they can only be split
by reading the partition lengths from the bitstream.

Change-Id: If7d7ea331cc78cb7efd74c4a976b720c9a655463

Adding capabilities with which the encoder can output frames
partition by partition, and the decoder can get input data
partition by partition.

Change-Id: Ieae0801480b8de8cd43c3c57dd3bab2e4c346fe0

The error-concealer is plugged in after any motion vectors have been
decoded. It tries to estimate any missing motion vectors from the
motion vectors of the previous frame. Intra blocks with missing
residual are replaced with inter blocks with estimated motion vectors.

This feature was developed in a separate sandbox
(sandbox/holmer/error-concealment).

Change-Id: I5c8917b031078d79dbafd90f6006680e84a23412

- correct spelling
- remove explicit file name w/\file (unnecessary when contained in the
  same file and prone to desync)

Change-Id: I68a3960ac5ab84d0f2e5c9b2e29799f26dfccf23

Changes 'The VP8 project' to 'The WebM project', for consistency
with other webmproject.org repositories.

Fixes issue #97.

Change-Id: I37c13ed5fbdb9d334ceef71c6350e9febed9bbba

When the license headers were updated, they accidentally contained
trailing whitespace, so unfortunately we have to touch all the files
again.

Change-Id: I236c05fade06589e417179c0444cb39b09e4200d

Change-Id: Ieebea089095d9073b3a94932791099f614ce120c

This renames the vpx_codec/ directory to vpx/, to allow applications
to more consistently reference these includes with the vpx/ prefix.
This allows the includes to be installed in /usr/local/include/vpx
rather than polluting the system includes directory with an
excessive number of includes.

Change-Id: I7b0652a20543d93f38f421c60b0bbccde4d61b4f

Replace all anonymous structs with struct name matching current typedef
minus _t.

Change-Id: I639295e8f1bc4651fffc9286a7dba5171c92ce92