WebM Experimental Codec Branch Snapshot

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#7a15907)

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

1 files changed, 0 insertions, 4 deletions

diff --git a/vpx/vpx_decoder.h b/vpx/vpx_decoder.h
index 0fc38c69f..ea2569daf 100644
--- a/vpx/vpx_decoder.h
+++ b/vpx/vpx_decoder.h
@@ -53,8 +53,6 @@ extern "C" {
 #define VPX_CODEC_CAP_PUT_SLICE  0x10000 /**< Will issue put_slice callbacks */
 #define VPX_CODEC_CAP_PUT_FRAME  0x20000 /**< Will issue put_frame callbacks */
 #define VPX_CODEC_CAP_POSTPROC   0x40000 /**< Can postprocess decoded frame */
-#define VPX_CODEC_CAP_ERROR_CONCEALMENT   0x80000 /**< Can conceal errors due to
-                                                       packet loss */
 #define VPX_CODEC_CAP_INPUT_PARTITION   0x100000 /**< Can receive encoded frames
                                                     one partition at a time */
 
@@ -66,8 +64,6 @@ extern "C" {
      *  The available flags are specified by VPX_CODEC_USE_* defines.
      */
 #define VPX_CODEC_USE_POSTPROC   0x10000 /**< Postprocess decoded frame */
-#define VPX_CODEC_USE_ERROR_CONCEALMENT 0x20000 /**< Conceal errors in decoded
-                                                     frames */
 #define VPX_CODEC_USE_INPUT_PARTITION   0x40000 /**< The input frame should be
                                                     passed to the decoder one
                                                     partition at a time */