private TilePartComponent[] DecodePackets(TilePartHeader tilePartHeader)
{
var tile = Image.Tiles[tilePartHeader.SOT.I_TileIndexNumber];
var tilePart = new TilePart(tile, tilePartHeader);
var tilePartComponents = new TilePartComponent[Image.Components.Length];
for (var iComponent = 0; iComponent < Image.Components.Length; iComponent++)
{
var tileComponent = tile.TileComponents[iComponent];
tilePartComponents[iComponent] = new TilePartComponent(tilePart, tileComponent);
}
var progressionOrder = tilePartHeader.COD.SG_ProgressionOrder;
if (progressionOrder == ProgressionOrder.LayerResolutionComponentPosition)
{
DecodePacketsInLayerResolutionComponentPositionOrder(tilePartHeader, tilePartComponents);
}
else
{
throw NotSupported(progressionOrder);
}
return(tilePartComponents);
}
private static double GetQuantizationStepSize(TilePartComponent tilePartComponent, Subband subband)
{
var qcc = tilePartComponent.QCC;
ThrowIf(qcc.QuantizationStyle == QuantizationStyle.NoQuantization);
// See E.1.1.1 "Determination of the quantization step size"
var ri = tilePartComponent.TileComponent.Component.ComponentSampleBitDepth;
var rb = ri + GetLog2SubbandGain(subband);
if (qcc.QuantizationStyle == QuantizationStyle.ScalarExpounded)
{
var qss = qcc.QuantizationStepSizes[subband.SubbandIndex];
return(Math.Pow(2, rb - qss.Exponent) * (1 + qss.Mantissa / Math.Pow(2, 11)));
}
else
{
throw NotSupported(qcc.QuantizationStyle);
}
}
private void StartDecodeCodeBlock(TilePartComponent tilePartComponent, CodeBlock codeBlock)
{
if (codeBlock.LengthInBytes > int.MaxValue - 2)
{
throw new NotSupportedException($"Code block too long ({codeBlock.LengthInBytes})");
}
var bytes = new byte[codeBlock.LengthInBytes + 2];
DataReader.Read(bytes.AsSpan(0, (int)codeBlock.LengthInBytes));
// Two 0xFF bytes must be added to flush the entropy coder (see D.4.1 "Expected codestream termination")
bytes[codeBlock.LengthInBytes] = 0xFF;
bytes[codeBlock.LengthInBytes + 1] = 0xFF;
codeBlock.DecodeTask = Task.Run(() =>
{
var coefficientDecoder = new CoefficientDecoder(codeBlock, bytes);
coefficientDecoder.Run(tilePartComponent);
});
}
private static void CopyToPixelDataBuffer(TilePartComponent tilePartComponent, Signal2D a, int[] buffer, int offset, int count)
{
var inverseDCLevelShifter = InverseDCLevelShifter.Create(tilePartComponent.ArithmeticType);
inverseDCLevelShifter.CopyToPixelDataBuffer(tilePartComponent.TileComponent.Component, a, buffer, offset, count);
}
protected sealed override void Dequantisize(Signal2D <T> transformCoefficientValues, TilePartComponent component, Subband subband)
{
var quantizationStepSize = GetQuantizationStepSize(component, subband);
if (quantizationStepSize != 1)
{
transformCoefficientValues.URange.GetBounds(out int u0, out int u1);
transformCoefficientValues.VRange.GetBounds(out int v0, out int v1);
Parallel.For(v0, v1, v =>
{
for (var u = u0; u < u1; u++)
{
ApplyQuantizationStepSize(transformCoefficientValues, u, v, quantizationStepSize);
}
});
}
}
protected sealed override void Dequantisize(Signal2D <T> transformCoefficientValues, TilePartComponent tilePartComponent, Subband subband)
{
// Nothing to do
}
public abstract void Dequantisize(Signal2D transformCoefficientValues, TilePartComponent tilePartComponent, Subband subband);
