Some imput formats and colour spaces have a different bitdepth
for their chroma (non-primary) component.  This commit adds
support to signal their bitdepth as described by the codec
independent code points.

This commit enables signalling a colour matrix index using
cicp_matrix_coefficients_idx (ISO/IEC 23001-8 codec independent code
points).

It adds the following options that replace the existing colorTransform
option:

 - colourMatrix: The coded representation according to ISO/IEC 23001-8.

 - convertPlyColourspace: Enables conversion to/from RGB using the
   indicated matrix.

Configuration files are updated to use the new option and to
signal the identity matrix in the case of direct GBR coding.

Sehoon Yea authored Sep 25, 2019 and David Flynn committed Nov 21, 2019

This adoption permits prediction of residuals between components of
the same attribute, coding the residual resulting from this second
prediction.

Yiting Shao authored Sep 23, 2019 and David Flynn committed Nov 21, 2019

This adoption allows determining the weights of each point's
predicting neighbours with a reduced influence of the, for
instance, z component.

This adoption permits encoding the geometry positions in an order other
than {x,y,z}.  The --geometry_axis_order option causes the encoder to
load data from the ply file in a different order.  The order is
signalled in the SPS and the decoder will label the output axis as
appropriate.

This adds:
 - a frame_idx syntax element to every geometry slice header.
 - (decoder) handling of a frame boundary data unit.

Frame boundaries are represented by changes in the value of frame_idx
or by the presence of a frame boundary data unit.

Satoru KUMA authored May 31, 2019 and David Flynn committed Nov 21, 2019

This provides a means to achieve spatial scalability for a G-PCC
bitstream.  For bitstreams encoded with aps_scalable_enabled_flag set,
the decoder may partially decode the geometry octree
(minGeomNodeSizeLog2) and the corresponding point attributes.  The
functionality is achieved by constraining the LoD generation process to
align with partial geometry decoding.

David Flynn authored Feb 13, 2019 and David Flynn committed Aug 12, 2019

Rather than code bypass bins using a simplified mode of the
arithmetic coder, this commit adds the ability to signal bypass bins
in a separate byte-reversed sub-stream.

Noritaka Iguchi authored Jul 02, 2019 and David Flynn committed Aug 12, 2019

This commit allow individual QP offsets to be specified for each
LoD/RAHT layer in attribute coding.

For each 2×2×2 block, a predicted block is produced by upconverting the
previous transform level.  The prediction is transformed and subtracted
from the transformed attributes at the encoder.

When the same geom_box_log2_scale is used for all slices, it is not
necessary to store them in slice headers.  This commit permits
signalling of the common value in the GPS.

Toshiyasu Sugio authored Mar 01, 2019 and David Flynn committed Apr 16, 2019

This commit introduces prediction by previously coded points within
the same level of detail using the predicting attribute coder.
The feature is controlled using --intraLodPredictionEnabled=0|1.

This method has been replaced by an LoD decimation method.

Valery Valentin authored Mar 05, 2019 and David Flynn committed Apr 16, 2019

This LoD generation (subsampling) method uses the Morton-based ordering
of points that is used to determine prediction neighbours.  Each LoD
level comprises 3/4 of the points of the previous.

This commit permits signalling a per-slice delta QP for luma and
chroma attribute components.  The delta is relative to the base
value derived from the APS.

NB: while syntax support and derivation processes are provided,
this commit does not contain any method to control the delta
QP value at the encoder.

Noritaka Iguchi authored Mar 27, 2019 and David Flynn committed Apr 16, 2019

This commit introduces control of the quantisation step size using
the familiar HEVC | AVC quantisation parameter.

This is part of a series attempting to remove unhelpful typedefs.

The commit adds a flag to conditionally enable/disable the feature.

Vladyslav Zakharchenko authored Dec 14, 2018 and David Flynn committed Feb 06, 2019

This uses a binary-tree to generate the levels-of-details for the
lifting/predicting transforms as an alternative to Euclidean distance
thresholding methods.

The configuration parameters seq_bounding_box_xyz0 and
seq_bounding_box_whd allow overriding the automatic derivation of
frame (sequence) bounding box, forcing the depth of the geometry
tree.

NB: seq_bounding_box_xyz0 and seq_bounding_box_whd are specified
    using unscaled co-ordinates.

NB: this patch does not signal these parameters in the SPS.

 - signal geom_slice_id / attr_geom_slice_id in geometry / attribute
   header.

 - attr_geom_slice_id set to current geom_slice_id to maintain
   relationship between attribute and geometry.

 - increment geom_slice_id after each round of encoding.

 - decoder checks that the attribute payload's attr_geom_slice_id
   corresponds to the most recently decoded geometry payload.

This commit provides trisoup_node_size_log2 as a replacement for
the following HLS syntax variables:
 - geom_codec_type (redundant wrt. triangle node size derivation)
 - trisoup_depth (redundant wrt. bounding box)
 - trisoup_triangle_level (semantics simplified)

The following config options have been removed:
 - geometryCodec (redundant wrt. trisoup_node_size_log2)
 - triSoupLevel  (replaced by trisoup_node_size_log2)
 - triSoupDepth  (unnecessary)
 - triSoupIntToOrigScale (redundant wrt. positionQuantizationScale)

Khaled Mammou authored Sep 22, 2018 and David Flynn committed Nov 01, 2018

Replace the k-d tree based nearest neighbour search with an approximate
search based upon the points in Morton order.

Toshiyasu Sugio authored Sep 20, 2018 and David Flynn committed Nov 01, 2018

This commit provides an ability to vary the number of direct neighbours
used in the predicting transform.  Mode 0 corresponds to the existing
averaging, and mode n selects the n-th nearest neighbour for direct
prediction.

The provided code has been reworked to:
 - rewrite unary coding to be a little more obvious
 - tidy the mode decision path
 - add configuration for max_num_direct_predictors (renamed from
   MaxNumPredCand)
 - now counts the number of single predictors, rather than prediction
   modes.

This commit provides a method to predict the child occupancy bits of a
node based on the node's 26 neighbours.  The prediction is used to
contextualise coding of each occupancy bit.

This tool requires the use of the occupancyAtlas for neighbour lookup.
NB: a restriction in the current implementation requires that the
atlas size is at most 8³.

intra_pred_max_node_size_log2: 6

Bitwise geometry occupancy coding uses a mapping table to select entropy
contexts.  This commit employs a dynamic mapping which is updated after
each coding operation, replacing the previous static mapping tables.

NB: the proposed version used a context with a halving period
(max_count) of 64 symbols.  However, this conflicts with another
adoption (512 symbols), and a wholesale replacement of the arithmetic
codec and context model.  To resolve the conflict, the existing halving
period (128) is used.

Khaled Mammou authored Sep 19, 2018 and David Flynn committed Nov 01, 2018

This commit allows bytewise encoding of occupancy symbols using the
dual-lut coder.

Khaled Mammou authored Aug 22, 2018 and David Flynn committed Aug 29, 2018

This commit removes the ability to vary quant_step_size on a per-LoD
basis.  This greatly simplifies the codec configuration, especially
when used in conjunction with dist2 derivation.

cfg update:
 - rename quantizationSteps* -> quantizationStep*
 - update quantizationStep* to single values:
   - lossless-geom lossy-attrs:        8, 16, 32, 64, 128, 256 [8bit]
   - lossless-geom nearlossless-attrs: no change
   - lossless-geom lossless-attrs:     no change
   - lossy-geom    lossy-attrs:        8                       [8bit]

 => 16-bit cat3 sequences are have 8-bit qs values multipled by 255

Khaled Mammou authored Aug 22, 2018 and David Flynn committed Aug 29, 2018

This commit replaces the hard coded threshold values with APS signalling.
The default configuration maintains the hard-coded threshold values based
on bitdepth.

This is an editorial change to improve naming clarity: attr_count
represents the number of elements (dimensionality) in an attribute
set rather than the total number of attributes.

Khaled Mammou authored Aug 27, 2018 and David Flynn committed Aug 29, 2018

This commit fixes an error in the hls: dist2 is capable of being a
64-bit value and must not be signalled as 32-bit.

This commit allows the attribute codec to be parametrised by attribute
bitdepth.  The attribute bitdepth is signalled in the attribute's sequence
parameter set description.  The specified bitdepth affects cliping in the
attribute prediction and reconstruction process.

This commit allows individual payloads to be inserted into the decoder
rather than the decoder expecting to decode each payload in a fixed
order.

When an output pointcloud is ready, the decoder will call a user
supplied callback with the conforming output pointcloud.  The user
may choose to rescale this point cloud as necessary.

This commit removes the "lossless" geometry bypass coding mode that simply
skipped coding of geometry and required the decoder to read the geometry
from the source video.  Bypass coding mode is replaced by octree coding.

This commit rewrites the codec high-level syntax:

 - the bitstream is divided into "bricks" (akin to an AVC/HEVC
   slice/tile).

 - sequence, geometry and attribute parameter sets describe the coding
   parameters in use generally and for a specific brick.

 - marshalling the bitstream payloads to a file format is achieved using
   a type-length-value encoding scheme.

Additionally, the triSoup bitstream scale and translation values have
been unified with (replaced by) the octree counterparts.  For
compatibility, existing command line parameters continue to function
as before.

NB: this commit does not incorporate flexibility in the decoding order.
The decoder requires the bitstream to be presented in a fixed order.