The geometry quantisation assumed that octree nodes were cubes.  The
addition of qt/bt partitioning modes breaks this premise.  This commit
addresses the following:

 - Only the to-be-coded bits, which may differ for each component, are
   quantised, rather than quantising all bits according to the tree
   depth (which would result in quantising already coded bits).

 - The occupancy mask (determining the non-coded occupancy bits) must
   be recomputed for each node.  Since the effect of quantisation is
   to prune back each sub-tree from the leaves, some nodes that would
   have had qt/bt partitions will not be coded, leaving an unequal
   reconstruction.  The solution is to terminate the shorter leaves
   earlier and to recompute the partition.

Xiang Zhang authored Jun 10, 2019 and David Flynn committed Nov 21, 2019

This adoption permits coding geometry with non-cubic bounding boxes.
Since the depth of the tree remains constant for cubic and non-cubic
bounding boxes with identical largest dimensions, quad-tree and
binary-tree partitions are introduced to avoid coding 'fractional'
positions.

The following configuration options control the placement of non-octree
partitions within the coding tree:

 --max_num_implicit_qtbt_before_ot
 --min_implicit_qtbt_size_log2

Geometry quantisation introduced an extra field to the point cloud
to hold scaled positions (to be restored after geometry coding is
complete).  This had a side effect of causing significant memory
increases since it applied to every instance of the point cloud.

Since it is not necessary to store both quantised and scaled positions
separately, this commit removes the extra storage and uses a method
similar to the decoder to represent partially quantised positions.

The geometry tree nodes contain a position element (pos) that identifies
the spatial position of the node.  At internal nodes this node position
is the partial position of a point and may either be represented using
the magnitude of the decoded points, or the magnitude of the current
depth.

The first form equates to:
 nextPos = curPos | (xyz << currentNodeSize)

The second:
 nextPos = (curPos << 1) | xyz

Where xyz represents a position bit from the coded occupancy.

In order to use the first form to determine neighbour relationships,
curPos must be shifted down to represent position within the current
depth.  This repeated shifting, along with the introduction of
simultaneous quantised and unquantised positions becomes increasingly
difficult to follow when adding non-cubic nodes (via OtQtBt).

This commit switches the representation to the second form above,
eliminating various shifted forms and duplicate state.  A decoded
positions is inverse quantised when reaching a leaf node.

Xiang Zhang authored Aug 19, 2019 and David Flynn committed Nov 21, 2019

This extends the geometry based quantisation scheme to:
 - add a per-slice QP offset, and
 - permit uniform quantisation of the whole slice without
   requiring signalling of an additional node QP offset.

Per node QP offset signalling is disabled by setting
positionQuantisationOctreeDepth=-1

Xiang Zhang authored Aug 19, 2019 and David Flynn committed Nov 21, 2019

This introduces a quantization scheme into the octree coding process,
enables adaptive geometry quantization for different regions of the
point cloud.  This in-loop scheme is independent of the any quantisation
performed in non-normative pre-processing at the input to the encoder.

At a particular depth of the octree, the remaining (uncoded) position
bits of each point are quantised according to a per-node (or rather,
per-subtree) QP.  The QP itself is signalled as an offset to a base QP.

The following configuration parameters are added:
  positionQuantisationEnabled
  positionBaseQp
  positionQuantisationOctreeDepth

Noritaka Iguchi authored Sep 27, 2019 and David Flynn committed Nov 21, 2019

A per-slice region may be defined with a qp offset.  Points within
the region have an offset applied to the per-level QP.

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

This commit adds the lossless YCgCoR colour transform.
The CTC configuration is updated to use YCgCoR for lossless
attribute coding instead of inter-component prediction on
GBR (colourMatrix=0) data.

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

In order to support bit depths higher than 8bit, this commit adds
an attr_t type to represent attribute data.  Existing uses of
uint8_t and uint16_t are converted to attr_t.

None of these methods need to be inlined.

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.

The GBR coding order matches the description in ISO/IEC 23001-8 for
the identity matrix (MatrixCoefficients=0).

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.

ChenJiafeng authored Oct 18, 2019 and David Flynn committed Nov 21, 2019

This adoption implements a different context selection method for the
isOne syntax element in attribute coding.

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 commit migrates PCCPointSet3::read and write to ply::read and write.

David Flynn authored Jun 21, 2018 and David Flynn committed Nov 21, 2019

This commit enables the codec to encapsulate more than one frame in the
coded bitstream.  The number of frames to encode is controlled by the
frameCount option.

Support is added to encode multiple source frames from separate ply
files based on a template input file name.  A printf-like "%d" directive
acts as a placeholder for the current frame number.

Decoding functions in a similar way with a each frame decoded from the
bitstream being written to a separate ply file named according to a
template pattern.

The first frame number used for file I/O may be set using the
firstFrameNum option.

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.

This converts an unrolled loop (with special case for the initial
iteration) to the rolled up form in order to improve readability.

For the lifting scheme, some APS parameters are always signalled.
However, some syntax elements are not needed depending upon the values
of attr_coding_type and lifting_scalability_enabled_flag.  This adoption
avoids signalling unnecessary syntax elements in these cases.

This commit refactors calling the LoD generation routines to pass
the aps rather than a long list of syntax variables.

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.

This commit extends the operating range of the forward and inverse
quantization tables in order to reduce distortion at low bit rates.

Consider candidates that are tied according to distance with the current
worst predictor in order to consistently use the lowest indexed candidate
and to prefer neighbours in coarser LoD to neighbours in current LoD.

This fixes an issue when during predictor construction, when
lodIndex == levelOfDetailCount causing the retained set to be empty.

The clang indent rules used to tidy the code cause undue indentation
when used with include guards.  This commit switches the only remaining
instance to use pgrama once.

David Flynn authored May 06, 2019 and David Flynn committed Aug 26, 2019

This commit provides a set of MPEG::PCC perl modules that may be used to
parse TMC13 log files.  An example script collect-tmc13.pl demonstrates
their use.

basketball_player_vox11 and dancer_vox11 are reduced to 64 frames.

Wei Zhang authored Jul 10, 2019 and David Flynn committed Aug 12, 2019

This avoids artefacts during trisoup generation by checking whether the
original slice partition interval is an integer multiple of the block
size W=2^(trisoup_node_size_log2). If not, the partition interval is
rounded up to the nearest integer that is exactly divisible by the block
size.

Yiting Shao authored Jun 14, 2019 and David Flynn committed Aug 12, 2019

This commit adds a process to limit the number of points per slice to be
within a hard upper limit and soft lower limit.

Yiting Shao authored Jun 14, 2019 and David Flynn committed Aug 12, 2019

Adjust the operation sequence of slice partition and geometry quantization. We
do geometry quantization first and then do the slice partition, so that the
point number of each slice would be kept in the predefined range under
lossless/lossy geometry coding conditions.

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.