hls: rename sps attr_count to attr_num_dimensions

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.

tmc3/AttributeDecoder.cpp

@@ -138,7 +138,7 @@ AttributeDecoder::decode(
   decoder.start(
     payload.data() + abhSize, payload.size() - abhSize, alphabetSize);
 
-  if (attr_desc.attr_count == 1) {
+  if (attr_desc.attr_num_dimensions == 1) {
     switch (attr_aps.attr_encoding) {
     case AttributeEncoding::kRAHTransform:
       decodeReflectancesRaht(attr_desc, attr_aps, decoder, pointCloud);
@@ -152,7 +152,7 @@ AttributeDecoder::decode(
       decodeReflectancesLift(attr_desc, attr_aps, decoder, pointCloud);
       break;
     }
-  } else if (attr_desc.attr_count == 3) {
+  } else if (attr_desc.attr_num_dimensions == 3) {
     switch (attr_aps.attr_encoding) {
     case AttributeEncoding::kRAHTransform:
       decodeColorsRaht(attr_desc, attr_aps, decoder, pointCloud);
@@ -167,7 +167,9 @@ AttributeDecoder::decode(
       break;
     }
   } else {
-    assert(attr_desc.attr_count == 1 || attr_desc.attr_count == 3);
+    assert(
+      attr_desc.attr_num_dimensions == 1
+      || attr_desc.attr_num_dimensions == 3);
   }
 
   decoder.stop();

tmc3/AttributeEncoder.cpp

@@ -271,7 +271,7 @@ AttributeEncoder::encode(
   const uint32_t alphabetSize = 64;
   encoder.start(int(pointCloud.getPointCount()), alphabetSize);
 
-  if (desc.attr_count == 1) {
+  if (desc.attr_num_dimensions == 1) {
     switch (attr_aps.attr_encoding) {
     case AttributeEncoding::kRAHTransform:
       encodeReflectancesTransformRaht(desc, attr_aps, pointCloud, encoder);
@@ -285,7 +285,7 @@ AttributeEncoder::encode(
       encodeReflectancesLift(desc, attr_aps, pointCloud, encoder);
       break;
     }
-  } else if (desc.attr_count == 3) {
+  } else if (desc.attr_num_dimensions == 3) {
     switch (attr_aps.attr_encoding) {
     case AttributeEncoding::kRAHTransform:
       encodeColorsTransformRaht(desc, attr_aps, pointCloud, encoder);
@@ -300,7 +300,7 @@ AttributeEncoder::encode(
       break;
     }
   } else {
-    assert(desc.attr_count == 1 || desc.attr_count == 3);
+    assert(desc.attr_num_dimensions == 1 || desc.attr_num_dimensions == 3);
   }
 
   uint32_t acDataLen = encoder.stop();

tmc3/PCCTMC3Encoder.h

@@ -127,12 +127,12 @@ public:
       attr_sps.cicp_video_full_range_flag = true;
 
       if (it.first == "color") {
-        attr_sps.attr_count = 3;
+        attr_sps.attr_num_dimensions = 3;
         attr_sps.attributeLabel = KnownAttributeLabel::kColour;
       }
 
       if (it.first == "reflectance") {
-        attr_sps.attr_count = 1;
+        attr_sps.attr_num_dimensions = 1;
         attr_sps.attributeLabel = KnownAttributeLabel::kReflectance;
       }
     }

tmc3/hls.h

@@ -132,7 +132,7 @@ enum class AttributeEncoding
 
 // invariant properties
 struct AttributeDescription {
-  int attr_count;
+  int attr_num_dimensions;
   int attr_instance_id;
   int attr_bitdepth;
   int cicp_colour_primaries_idx;

tmc3/io_hls.cpp

@@ -90,7 +90,8 @@ write(const SequenceParameterSet& sps)
   int num_attribute_sets = int(sps.attributeSets.size());
   bs.writeUe(num_attribute_sets);
   for (const auto& attr : sps.attributeSets) {
-    bs.writeUe(attr.attr_count);
+    // todo(df): should be attr_num_dimensions_minus1
+    bs.writeUe(attr.attr_num_dimensions);
     bs.writeUe(attr.attr_instance_id);
     bs.writeUe(attr.attr_bitdepth);
     bs.writeUe(attr.cicp_colour_primaries_idx);
@@ -146,7 +147,7 @@ parseSps(const PayloadBuffer& buf)
   for (int i = 0; i < num_attribute_sets; i++) {
     sps.attributeSets.emplace_back();
     auto& attr = sps.attributeSets.back();
-    bs.readUe(&attr.attr_count);
+    bs.readUe(&attr.attr_num_dimensions);
     bs.readUe(&attr.attr_instance_id);
     bs.readUe(&attr.attr_bitdepth);
     bs.readUe(&attr.cicp_colour_primaries_idx);