hls/m47398: add common signalling of geom_box_log2_scale to gps

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.

tmc3/encoder.cpp

@@ -193,6 +193,8 @@ PCCTMC3Encoder3::fixupParameterSets(EncoderParams* params)
   // the encoder writes out the slice origin in the GBH
   // NB: this may be disabled during encoding
   params->gps.geom_box_present_flag = true;
+  params->gps.geom_box_log2_scale_present_flag = true;
+  params->gps.gps_geom_box_log2_scale = 0;
 
   // fixup attribute parameters
   for (auto it : params->attributeIdxMap) {

tmc3/hls.h

@@ -169,6 +169,13 @@ struct GeometryParameterSet {
   // geom_box_origin_xyz.
   int geom_box_present_flag;
 
+  // Indicates the presence of gps_geom_box_log2_scale and
+  // geom_box_log2_scale.
+  bool geom_box_log2_scale_present_flag;
+
+  // Default scaling factor for per-slice geometry box origin
+  int gps_geom_box_log2_scale;
+
   // Controls the ability to represent multiple points (with associated
   // attributes) at the same spatial position.
   bool geom_unique_points_flag;
@@ -221,6 +228,15 @@ struct GeometryBrickHeader {
   // todo(df): minus1?
   int geom_max_node_size_log2;
   int geom_num_points;
+
+  int geomBoxLog2Scale(const GeometryParameterSet& gps) const
+  {
+    if (!gps.geom_box_present_flag)
+      return 0;
+    if (!gps.geom_box_log2_scale_present_flag)
+      return gps.gps_geom_box_log2_scale;
+    return geom_box_log2_scale;
+  }
 };
 
 //============================================================================

tmc3/io_hls.cpp

@@ -190,6 +190,11 @@ write(const GeometryParameterSet& gps)
   bs.writeUe(gps.gps_geom_parameter_set_id);
   bs.writeUe(gps.gps_seq_parameter_set_id);
   bs.write(gps.geom_box_present_flag);
+  if (gps.geom_box_present_flag) {
+    bs.write(gps.geom_box_log2_scale_present_flag);
+    if (!gps.geom_box_log2_scale_present_flag)
+      bs.writeUe(gps.gps_geom_box_log2_scale);
+  }
   bs.write(gps.geom_unique_points_flag);
   bs.write(gps.neighbour_context_restriction_flag);
   bs.write(gps.inferred_direct_coding_mode_enabled_flag);
@@ -219,6 +224,11 @@ parseGps(const PayloadBuffer& buf)
   bs.readUe(&gps.gps_geom_parameter_set_id);
   bs.readUe(&gps.gps_seq_parameter_set_id);
   bs.read(&gps.geom_box_present_flag);
+  if (gps.geom_box_present_flag) {
+    bs.read(&gps.geom_box_log2_scale_present_flag);
+    if (!gps.geom_box_log2_scale_present_flag)
+      bs.readUe(&gps.gps_geom_box_log2_scale);
+  }
   bs.read(&gps.geom_unique_points_flag);
   bs.read(&gps.neighbour_context_restriction_flag);
   bs.read(&gps.inferred_direct_coding_mode_enabled_flag);
@@ -358,11 +368,13 @@ write(
   bs.writeUe(gbh.geom_slice_id);
 
   if (gps.geom_box_present_flag) {
-    int geom_box_origin_x = gbh.geomBoxOrigin.x() >> gbh.geom_box_log2_scale;
-    int geom_box_origin_y = gbh.geomBoxOrigin.y() >> gbh.geom_box_log2_scale;
-    int geom_box_origin_z = gbh.geomBoxOrigin.z() >> gbh.geom_box_log2_scale;
+    int geomBoxLog2Scale = gbh.geomBoxLog2Scale(gps);
+    int geom_box_origin_x = gbh.geomBoxOrigin.x() >> geomBoxLog2Scale;
+    int geom_box_origin_y = gbh.geomBoxOrigin.y() >> geomBoxLog2Scale;
+    int geom_box_origin_z = gbh.geomBoxOrigin.z() >> geomBoxLog2Scale;
 
-    bs.writeUe(gbh.geom_box_log2_scale);
+    if (gps.geom_box_log2_scale_present_flag)
+      bs.writeUe(gbh.geom_box_log2_scale);
     bs.writeUe(geom_box_origin_x);
     bs.writeUe(geom_box_origin_y);
     bs.writeUe(geom_box_origin_z);
@@ -388,7 +400,8 @@ parseGbh(
   bs.readUe(&gbh.geom_slice_id);
 
   if (gps.geom_box_present_flag) {
-    bs.readUe(&gbh.geom_box_log2_scale);
+    if (gps.geom_box_log2_scale_present_flag)
+      bs.readUe(&gbh.geom_box_log2_scale);
 
     int geom_box_origin_x;
     int geom_box_origin_y;
@@ -396,9 +409,10 @@ parseGbh(
     bs.readUe(&geom_box_origin_x);
     bs.readUe(&geom_box_origin_y);
     bs.readUe(&geom_box_origin_z);
-    gbh.geomBoxOrigin.x() = geom_box_origin_x << gbh.geom_box_log2_scale;
-    gbh.geomBoxOrigin.y() = geom_box_origin_y << gbh.geom_box_log2_scale;
-    gbh.geomBoxOrigin.z() = geom_box_origin_z << gbh.geom_box_log2_scale;
+    int geomBoxLog2Scale = gbh.geomBoxLog2Scale(gps);
+    gbh.geomBoxOrigin.x() = geom_box_origin_x << geomBoxLog2Scale;
+    gbh.geomBoxOrigin.y() = geom_box_origin_y << geomBoxLog2Scale;
+    gbh.geomBoxOrigin.z() = geom_box_origin_z << geomBoxLog2Scale;
   }
 
   bs.readUe(&gbh.geom_max_node_size_log2);