attr/m47401: derive quant stepsize from quantisation parameter

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

cfg/octree-liftt-ctc-lossless-geom-lossy-attrs.yaml

@@ -42,14 +42,13 @@ categories:
      -
        - !conditional '${has_refl}'
        - adaptivePredictionThreshold: '$eval{ 1 << (8 - 2) }'
-       - quantizationStepLuma:
-           r01: 256
-           r02: 128
-           r03:  64
-           r04:  32
-           r05:  16
-           r06:   8
-       - quantizationStepChroma: 0
+       - qp:
+           r01: 52
+           r02: 46
+           r03: 40
+           r04: 34
+           r05: 28
+           r06: 22
        - bitdepth: 8
        - attribute: reflectance
 
@@ -58,20 +57,14 @@ categories:
      -
        - !conditional '${has_colour}'
        - adaptivePredictionThreshold: '$eval{ 1 << (8 - 2) }'
-       - quantizationStepLuma:
-           r01: 256
-           r02: 128
-           r03:  64
-           r04:  32
-           r05:  16
-           r06:   8
-       - quantizationStepChroma:
-           r01: 256
-           r02: 128
-           r03:  64
-           r04:  32
-           r05:  16
-           r06:   8
+       - qp:
+           r01: 52
+           r02: 46
+           r03: 40
+           r04: 34
+           r05: 28
+           r06: 22
+       - qpChromaOffset: 0
        - bitdepth: 8
        - attribute: color
 

cfg/octree-liftt-ctc-lossy-geom-lossy-attrs.yaml

@@ -51,14 +51,13 @@ categories:
        -
          - !conditional '${has_refl}'
          - adaptivePredictionThreshold: '$eval{ 1 << (8 - 2) }'
-         - quantizationStepLuma:
-             r01: 256
-             r02: 128
-             r03:  64
-             r04:  32
-             r05:  16
-             r06:   8
-         - quantizationStepChroma: 0
+         - qp:
+             r01: 52
+             r02: 46
+             r03: 40
+             r04: 34
+             r05: 28
+             r06: 22
          - bitdepth: 8
          - attribute: reflectance
 
@@ -67,20 +66,14 @@ categories:
        -
          - !conditional '${has_colour}'
          - adaptivePredictionThreshold: '$eval{ 1 << (8 - 2) }'
-         - quantizationStepLuma:
-             r01: 256
-             r02: 128
-             r03:  64
-             r04:  32
-             r05:  16
-             r06:   8
-         - quantizationStepChroma:
-             r01: 256
-             r02: 128
-             r03:  64
-             r04:  32
-             r05:  16
-             r06:   8
+         - qp:
+             r01: 52
+             r02: 46
+             r03: 40
+             r04: 34
+             r05: 28
+             r06: 22
+         - qpChromaOffset: 0
          - bitdepth: 8
          - attribute: color
 

cfg/octree-predt-ctc-lossless-geom-lossless-attrs.yaml

@@ -47,8 +47,7 @@ categories:
        -
          - !conditional '${has_refl}'
          - adaptivePredictionThreshold: '$eval{ 1 << (8 - 2) }'
-         - quantizationStepLuma: 0
-         - quantizationStepChroma: 0
+         - qp: 4
          - bitdepth: 8
          - attribute: reflectance
 
@@ -57,8 +56,8 @@ categories:
        -
          - !conditional '${has_colour}'
          - adaptivePredictionThreshold: '$eval{ 1 << (8 - 2) }'
-         - quantizationStepLuma: 0
-         - quantizationStepChroma: 0
+         - qp: 4
+         - qpChromaOffset: 0
          - bitdepth: 8
          - attribute: color
 

cfg/octree-predt-ctc-lossless-geom-nearlossless-attrs.yaml

@@ -43,13 +43,12 @@ categories:
      -
        - !conditional '${has_refl}'
        - adaptivePredictionThreshold: '$eval{ 1 << (8 - 2) }'
-       - quantizationStepLuma:
-           r01:  2
-           r02:  4
-           r03:  8
-           r04: 16
-           r05: 32
-       - quantizationStepChroma: 0
+       - qp:
+           r01: 10
+           r02: 16
+           r03: 22
+           r04: 28
+           r05: 34
        - bitdepth: 8
        - attribute: reflectance
 
@@ -58,18 +57,13 @@ categories:
      -
        - !conditional '${has_colour}'
        - adaptivePredictionThreshold: '$eval{ 1 << (8 - 2) }'
-       - quantizationStepLuma:
-           r01:  2
-           r02:  4
-           r03:  8
-           r04: 16
-           r05: 32
-       - quantizationStepChroma:
-           r01:  2
-           r02:  4
-           r03:  8
-           r04: 16
-           r05: 32
+       - qp:
+           r01: 10
+           r02: 16
+           r03: 22
+           r04: 28
+           r05: 34
+       - qpChromaOffset: 0
        - bitdepth: 8
        - attribute: color
 

cfg/octree-raht-ctc-lossless-geom-lossy-attrs.yaml

@@ -31,14 +31,13 @@ categories:
      -
        - !conditional '${has_refl}'
        - rahtLeafDecimationDepth: 0
-       - quantizationStepLuma:
-           r01: 256
-           r02: 128
-           r03:  64
-           r04:  32
-           r05:  16
-           r06:   8
-       - quantizationStepChroma: 0
+       - qp:
+           r01: 52
+           r02: 46
+           r03: 40
+           r04: 34
+           r05: 28
+           r06: 22
        - bitdepth: 8
        - attribute: reflectance
 
@@ -47,21 +46,15 @@ categories:
      -
        - !conditional '${has_colour}'
        - rahtLeafDecimationDepth: 0
-       - quantizationStepLuma:
-           r01: 256
-           r02: 128
-           r03:  64
-           r04:  32
-           r05:  16
-           r06:   8
-       - quantizationStepChroma:
-           # NB: raht doesn't yet support quantizationStepChroma
-           r01: 256
-           r02: 128
-           r03:  64
-           r04:  32
-           r05:  16
-           r06:   8
+       - qp:
+           r01: 52
+           r02: 46
+           r03: 40
+           r04: 34
+           r05: 28
+           r06: 22
+       # NB: raht doesn't yet support qpChromaOffset
+       - qpChromaOffset: 0
        - bitdepth: 8
        - attribute: color
 

cfg/octree-raht-ctc-lossy-geom-lossy-attrs.yaml

@@ -36,14 +36,13 @@ categories:
      -
        - !conditional '${has_refl}'
        - rahtLeafDecimationDepth: 0
-       - quantizationStepLuma:
-           r01: 256
-           r02: 128
-           r03:  64
-           r04:  32
-           r05:  16
-           r06:   8
-       - quantizationStepChroma: 0
+       - qp:
+           r01: 52
+           r02: 46
+           r03: 40
+           r04: 34
+           r05: 28
+           r06: 22
        - bitdepth: 8
        - attribute: reflectance
 
@@ -52,21 +51,15 @@ categories:
      -
        - !conditional '${has_colour}'
        - rahtLeafDecimationDepth: 0
-       - quantizationStepLuma:
-           r01: 256
-           r02: 128
-           r03:  64
-           r04:  32
-           r05:  16
-           r06:   8
-       - quantizationStepChroma:
-           # NB: raht doesn't yet support quantizationStepChroma
-           r01: 256
-           r02: 128
-           r03:  64
-           r04:  32
-           r05:  16
-           r06:   8
+       - qp:
+           r01: 52
+           r02: 46
+           r03: 40
+           r04: 34
+           r05: 28
+           r06: 22
+       # NB: raht doesn't yet support quantizationStepChroma
+       - qpChromaOffset: 0
        - bitdepth: 8
        - attribute: color
 

cfg/trisoup-liftt-ctc-lossy-geom-lossy-attrs.yaml

@@ -44,20 +44,14 @@ categories:
      -
        - !conditional '${has_colour}'
        - adaptivePredictionThreshold: '$eval{ 1 << (8 - 2) }'
-       - quantizationStepLuma:
-           r01: 256
-           r02: 128
-           r03:  64
-           r04:  32
-           r05:  16
-           r06:   8
-       - quantizationStepChroma:
-           r01: 256
-           r02: 128
-           r03:  64
-           r04:  32
-           r05:  16
-           r06:   8
+       - qp:
+           r01: 52
+           r02: 46
+           r03: 40
+           r04: 34
+           r05: 28
+           r06: 22
+       - qpChromaOffset: 0
        - bitdepth: 8
        - attribute: color
 

cfg/trisoup-raht-ctc-lossy-geom-lossy-attrs.yaml

@@ -33,21 +33,15 @@ categories:
      -
        - !conditional '${has_colour}'
        - rahtLeafDecimationDepth: 0
-       - quantizationStepLuma:
-           r01: 256
-           r02: 128
-           r03:  64
-           r04:  32
-           r05:  16
-           r06:   8
-       - quantizationStepChroma:
-           # NB: raht doesn't yet support quantizationStepChroma
-           r01: 256
-           r02: 128
-           r03:  64
-           r04:  32
-           r05:  16
-           r06:   8
+       - qp:
+           r01: 52
+           r02: 46
+           r03: 40
+           r04: 34
+           r05: 28
+           r06: 22
+       # NB: raht doesn't yet support quantizationStepChroma
+       - qpChromaOffset: 0
        - bitdepth: 8
        - attribute: color
 

doc/README.options.md

@@ -234,9 +234,6 @@ Sets coefficients to zero in the bottom n levels of the RAHT tree.
 This option provides a means to perform chroma-subsampling.  Applies
 when `attribute=colour` only.
 
-### `--rahtQuantizationStep=INT-VALUE`
-Deprecated -- use `quantizationStepsLuma`.
-
 ### `--rahtDepth=INT-VALUE`
 Number of bits for Morton representation of RAHT co-ordinate
 components.
@@ -268,13 +265,13 @@ Controls the level-of-detail generation method:
   | 0     | Binary-tree based               |
   | 1     | Euclidean distance thresholding |
 
-### `--quantizationStepLuma=INT-VALUE`
-Attribute's luma quantization step size.
-
-### `--quantizationStepChroma=INT-VALUE`
-Attribute's chroma quantization step size.  Only applies when
-`attribute=colour`.
-
 ### `--dist2=INT-VALUE|INT-VALUE-LIST`
 Attribute's list of squared distances, or initial value for automatic
 derivation.
+
+### `--qp=INT-VALUE`
+Attribute's luma quantization parameter.
+
+### `--qpChromaOffset=INT-VALUE`
+Attribute's chroma quantization quantization parameter relative to luma.
+Only applies when `attribute=colour`.

tmc3/AttributeDecoder.cpp

@@ -151,7 +151,8 @@ AttributeDecoder::decode(
   PCCPointSet3& pointCloud)
 {
   int abhSize;
-  /* AttributeBrickHeader abh = */ parseAbh(payload, &abhSize);
+  AttributeBrickHeader abh = parseAbh(attr_aps, payload, &abhSize);
+  Quantizers qstep = deriveQuantSteps(attr_aps);
 
   PCCResidualsDecoder decoder;
   decoder.start(payload.data() + abhSize, payload.size() - abhSize);
@@ -159,29 +160,29 @@ AttributeDecoder::decode(
   if (attr_desc.attr_num_dimensions == 1) {
     switch (attr_aps.attr_encoding) {
     case AttributeEncoding::kRAHTransform:
-      decodeReflectancesRaht(attr_desc, attr_aps, decoder, pointCloud);
+      decodeReflectancesRaht(attr_desc, attr_aps, qstep, decoder, pointCloud);
       break;
 
     case AttributeEncoding::kPredictingTransform:
-      decodeReflectancesPred(attr_desc, attr_aps, decoder, pointCloud);
+      decodeReflectancesPred(attr_desc, attr_aps, qstep, decoder, pointCloud);
       break;
 
     case AttributeEncoding::kLiftingTransform:
-      decodeReflectancesLift(attr_desc, attr_aps, decoder, pointCloud);
+      decodeReflectancesLift(attr_desc, attr_aps, qstep, decoder, pointCloud);
       break;
     }
   } else if (attr_desc.attr_num_dimensions == 3) {
     switch (attr_aps.attr_encoding) {
     case AttributeEncoding::kRAHTransform:
-      decodeColorsRaht(attr_desc, attr_aps, decoder, pointCloud);
+      decodeColorsRaht(attr_desc, attr_aps, qstep, decoder, pointCloud);
       break;
 
     case AttributeEncoding::kPredictingTransform:
-      decodeColorsPred(attr_desc, attr_aps, decoder, pointCloud);
+      decodeColorsPred(attr_desc, attr_aps, qstep, decoder, pointCloud);
       break;
 
     case AttributeEncoding::kLiftingTransform:
-      decodeColorsLift(attr_desc, attr_aps, decoder, pointCloud);
+      decodeColorsLift(attr_desc, attr_aps, qstep, decoder, pointCloud);
       break;
     }
   } else {
@@ -231,6 +232,7 @@ void
 AttributeDecoder::decodeReflectancesPred(
   const AttributeDescription& desc,
   const AttributeParameterSet& aps,
+  const Quantizers& qstep,
   PCCResidualsDecoder& decoder,
   PCCPointSet3& pointCloud)
 {
@@ -261,7 +263,7 @@ AttributeDecoder::decodeReflectancesPred(
   for (size_t predictorIndex = 0; predictorIndex < pointCount;
        ++predictorIndex) {
     auto& predictor = predictors[predictorIndex];
-    const int64_t qs = aps.quant_step_size_luma;
+    const int64_t qs = qstep[0];
     computeReflectancePredictionWeights(
       aps, pointCloud, indexesLOD, predictor, decoder);
     const uint32_t pointIndex = indexesLOD[predictorIndex];
@@ -269,7 +271,8 @@ AttributeDecoder::decodeReflectancesPred(
     const uint32_t attValue0 = decoder.decode();
     const int64_t quantPredAttValue =
       predictor.predictReflectance(pointCloud, indexesLOD);
-    const int64_t delta = PCCInverseQuantization(UIntToInt(attValue0), qs);
+    const int64_t delta =
+      PCCInverseQuantization(UIntToInt(attValue0), qs, true);
     const int64_t reconstructedQuantAttValue = quantPredAttValue + delta;
     reflectance = uint16_t(
       PCCClip(reconstructedQuantAttValue, int64_t(0), maxReflectance));
@@ -318,6 +321,7 @@ void
 AttributeDecoder::decodeColorsPred(
   const AttributeDescription& desc,
   const AttributeParameterSet& aps,
+  const Quantizers& qstep,
   PCCResidualsDecoder& decoder,
   PCCPointSet3& pointCloud)
 {
@@ -348,8 +352,8 @@ AttributeDecoder::decodeColorsPred(
   for (size_t predictorIndex = 0; predictorIndex < pointCount;
        ++predictorIndex) {
     auto& predictor = predictors[predictorIndex];
-    const int64_t qs = aps.quant_step_size_luma;
-    const int64_t qs2 = aps.quant_step_size_chroma;
+    const int64_t qs = qstep[0];
+    const int64_t qs2 = qstep[1];
     computeColorPredictionWeights(
       aps, pointCloud, indexesLOD, predictor, decoder);
     decoder.decode(values);
@@ -358,14 +362,16 @@ AttributeDecoder::decodeColorsPred(
     const Vec3<uint8_t> predictedColor =
       predictor.predictColor(pointCloud, indexesLOD);
     const int64_t quantPredAttValue = predictedColor[0];
-    const int64_t delta = PCCInverseQuantization(UIntToInt(values[0]), qs);
+    const int64_t delta =
+      PCCInverseQuantization(UIntToInt(values[0]), qs, true);
     const int64_t reconstructedQuantAttValue = quantPredAttValue + delta;
     int64_t clipMax = (1 << desc.attr_bitdepth) - 1;
     color[0] =
       uint8_t(PCCClip(reconstructedQuantAttValue, int64_t(0), clipMax));
     for (size_t k = 1; k < 3; ++k) {
       const int64_t quantPredAttValue = predictedColor[k];
-      const int64_t delta = PCCInverseQuantization(UIntToInt(values[k]), qs2);
+      const int64_t delta =
+        PCCInverseQuantization(UIntToInt(values[k]), qs2, true);
       const int64_t reconstructedQuantAttValue = quantPredAttValue + delta;
       color[k] =
         uint8_t(PCCClip(reconstructedQuantAttValue, int64_t(0), clipMax));
@@ -379,6 +385,7 @@ void
 AttributeDecoder::decodeReflectancesRaht(
   const AttributeDescription& desc,