/// <summary>
/// Initializes a new instance of the <see cref="ScanDecoder"/> class.
/// </summary>
/// <param name="stream">The input stream.</param>
/// <param name="frame">The image frame.</param>
/// <param name="dcHuffmanTables">The DC Huffman tables.</param>
/// <param name="acHuffmanTables">The AC Huffman tables.</param>
/// <param name="fastACTables">The fast AC decoding tables.</param>
/// <param name="componentsLength">The length of the components. Different to the array length.</param>
/// <param name="restartInterval">The reset interval.</param>
/// <param name="spectralStart">The spectral selection start.</param>
/// <param name="spectralEnd">The spectral selection end.</param>
/// <param name="successiveHigh">The successive approximation bit high end.</param>
/// <param name="successiveLow">The successive approximation bit low end.</param>
public ScanDecoder(
DoubleBufferedStreamReader stream,
JpegFrame frame,
HuffmanTables dcHuffmanTables,
HuffmanTables acHuffmanTables,
FastACTables fastACTables,
int componentsLength,
int restartInterval,
int spectralStart,
int spectralEnd,
int successiveHigh,
int successiveLow)
{
this.dctZigZag = ZigZag.CreateUnzigTable();
this.stream = stream;
this.frame = frame;
this.dcHuffmanTables = dcHuffmanTables;
this.acHuffmanTables = acHuffmanTables;
this.fastACTables = fastACTables;
this.components = frame.Components;
this.marker = JpegConstants.Markers.XFF;
this.markerPosition = 0;
this.componentsLength = componentsLength;
this.restartInterval = restartInterval;
this.spectralStart = spectralStart;
this.spectralEnd = spectralEnd;
this.successiveHigh = successiveHigh;
this.successiveLow = successiveLow;
}
public unsafe void Quantize(int seed)
{
var block = new Block8x8F();
block.LoadFrom(Create8x8RoundedRandomFloatData(-2000, 2000, seed));
var qt = new Block8x8F();
qt.LoadFrom(Create8x8RoundedRandomFloatData(-2000, 2000, seed));
var unzig = ZigZag.CreateUnzigTable();
int *expectedResults = stackalloc int[Block8x8F.Size];
ReferenceImplementations.QuantizeRational(&block, expectedResults, &qt, unzig.Data);
var actualResults = default(Block8x8F);
Block8x8F.Quantize(&block, &actualResults, &qt, unzig.Data);
for (int i = 0; i < Block8x8F.Size; i++)
{
int expected = expectedResults[i];
int actual = (int)actualResults[i];
Assert.Equal(expected, actual);
}
}
public void ZigZagCanHandleAllPossibleCoefficients()
{
// Mimic the behaviour of the huffman scan decoder using all possible byte values
short[] block = new short[64];
var zigzag = ZigZag.CreateUnzigTable();
for (int h = 0; h < 255; h++)
{
for (int i = 1; i < 64; i++)
{
int s = h;
int r = s >> 4;
s &= 15;
if (s != 0)
{
i += r;
block[zigzag[i++]] = (short)s;
}
else
{
if (r == 0)
{
break;
}
i += 16;
}
}
}
}
/// <summary>
/// Creates and initializes a new <see cref="ComputationData"/> instance
/// </summary>
/// <returns>The <see cref="ComputationData"/></returns>
public static ComputationData Create()
{
ComputationData data = default;
data.Unzig = ZigZag.CreateUnzigTable();
return(data);
}
/// <summary>
/// Initializes a new instance of the <see cref="HuffmanScanDecoder"/> class.
/// </summary>
/// <param name="stream">The input stream.</param>
/// <param name="frame">The image frame.</param>
/// <param name="dcHuffmanTables">The DC Huffman tables.</param>
/// <param name="acHuffmanTables">The AC Huffman tables.</param>
/// <param name="componentsLength">The length of the components. Different to the array length.</param>
/// <param name="restartInterval">The reset interval.</param>
/// <param name="spectralStart">The spectral selection start.</param>
/// <param name="spectralEnd">The spectral selection end.</param>
/// <param name="successiveHigh">The successive approximation bit high end.</param>
/// <param name="successiveLow">The successive approximation bit low end.</param>
public HuffmanScanDecoder(
DoubleBufferedStreamReader stream,
JpegFrame frame,
HuffmanTable[] dcHuffmanTables,
HuffmanTable[] acHuffmanTables,
int componentsLength,
int restartInterval,
int spectralStart,
int spectralEnd,
int successiveHigh,
int successiveLow)
{
this.dctZigZag = ZigZag.CreateUnzigTable();
this.stream = stream;
this.scanBuffer = new HuffmanScanBuffer(stream);
this.frame = frame;
this.dcHuffmanTables = dcHuffmanTables;
this.acHuffmanTables = acHuffmanTables;
this.components = frame.Components;
this.componentsLength = componentsLength;
this.restartInterval = restartInterval;
this.todo = restartInterval;
this.spectralStart = spectralStart;
this.spectralEnd = spectralEnd;
this.successiveHigh = successiveHigh;
this.successiveLow = successiveLow;
}
/// <summary>
/// Encodes the image with no subsampling.
/// </summary>
/// <typeparam name="TPixel">The pixel format.</typeparam>
/// <param name="pixels">The pixel accessor providing access to the image pixels.</param>
/// <param name="cancellationToken">The token to monitor for cancellation.</param>
private void Encode444 <TPixel>(Image <TPixel> pixels, CancellationToken cancellationToken)
where TPixel : unmanaged, IPixel <TPixel>
{
// TODO: Need a JpegScanEncoder<TPixel> class or struct that encapsulates the scan-encoding implementation. (Similar to JpegScanDecoder.)
// (Partially done with YCbCrForwardConverter<TPixel>)
Block8x8F temp1 = default;
Block8x8F temp2 = default;
Block8x8F onStackLuminanceQuantTable = this.luminanceQuantTable;
Block8x8F onStackChrominanceQuantTable = this.chrominanceQuantTable;
var unzig = ZigZag.CreateUnzigTable();
// ReSharper disable once InconsistentNaming
int prevDCY = 0, prevDCCb = 0, prevDCCr = 0;
var pixelConverter = YCbCrForwardConverter <TPixel> .Create();
ImageFrame <TPixel> frame = pixels.Frames.RootFrame;
Buffer2D <TPixel> pixelBuffer = frame.PixelBuffer;
for (int y = 0; y < pixels.Height; y += 8)
{
cancellationToken.ThrowIfCancellationRequested();
var currentRows = new RowOctet <TPixel>(pixelBuffer, y);
for (int x = 0; x < pixels.Width; x += 8)
{
pixelConverter.Convert(frame, x, y, currentRows);
prevDCY = this.WriteBlock(
QuantIndex.Luminance,
prevDCY,
ref pixelConverter.Y,
ref temp1,
ref temp2,
ref onStackLuminanceQuantTable,
ref unzig);
prevDCCb = this.WriteBlock(
QuantIndex.Chrominance,
prevDCCb,
ref pixelConverter.Cb,
ref temp1,
ref temp2,
ref onStackChrominanceQuantTable,
ref unzig);
prevDCCr = this.WriteBlock(
QuantIndex.Chrominance,
prevDCCr,
ref pixelConverter.Cr,
ref temp1,
ref temp2,
ref onStackChrominanceQuantTable,
ref unzig);
}
}
}
/// <summary>
/// Encodes the image with no subsampling.
/// </summary>
/// <typeparam name="TPixel">The pixel format.</typeparam>
/// <param name="pixels">The pixel accessor providing access to the image pixels.</param>
private void Encode444 <TPixel>(Image <TPixel> pixels)
where TPixel : struct, IPixel <TPixel>
{
// TODO: Need a JpegScanEncoder<TPixel> class or struct that encapsulates the scan-encoding implementation. (Similar to JpegScanDecoder.)
// (Partially done with YCbCrForwardConverter<TPixel>)
Block8x8F temp1 = default;
Block8x8F temp2 = default;
Block8x8F onStackLuminanceQuantTable = this.luminanceQuantTable;
Block8x8F onStackChrominanceQuantTable = this.chrominanceQuantTable;
var unzig = ZigZag.CreateUnzigTable();
// ReSharper disable once InconsistentNaming
int prevDCY = 0, prevDCCb = 0, prevDCCr = 0;
var pixelConverter = YCbCrForwardConverter <TPixel> .Create();
for (int y = 0; y < pixels.Height; y += 8)
{
for (int x = 0; x < pixels.Width; x += 8)
{
pixelConverter.Convert(pixels.Frames.RootFrame, x, y);
prevDCY = this.WriteBlock(
QuantIndex.Luminance,
prevDCY,
&pixelConverter.Y,
&temp1,
&temp2,
&onStackLuminanceQuantTable,
unzig.Data);
prevDCCb = this.WriteBlock(
QuantIndex.Chrominance,
prevDCCb,
&pixelConverter.Cb,
&temp1,
&temp2,
&onStackChrominanceQuantTable,
unzig.Data);
prevDCCr = this.WriteBlock(
QuantIndex.Chrominance,
prevDCCr,
&pixelConverter.Cr,
&temp1,
&temp2,
&onStackChrominanceQuantTable,
unzig.Data);
}
}
}
public unsafe void DequantizeBlock(int seed)
{
Block8x8F original = CreateRandomFloatBlock(-500, 500, seed);
Block8x8F qt = CreateRandomFloatBlock(0, 10, seed + 42);
var unzig = ZigZag.CreateUnzigTable();
Block8x8F expected = original;
Block8x8F actual = original;
ReferenceImplementations.DequantizeBlock(&expected, &qt, unzig.Data);
Block8x8F.DequantizeBlock(&actual, &qt, unzig.Data);
this.CompareBlocks(expected, actual, 0);
}
/// <summary>
/// Initializes a new instance of the <see cref="HuffmanScanDecoder"/> class.
/// </summary>
/// <param name="stream">The input stream.</param>
/// <param name="converter">Spectral to pixel converter.</param>
/// <param name="cancellationToken">The token to monitor cancellation.</param>
public HuffmanScanDecoder(
BufferedReadStream stream,
SpectralConverter converter,
CancellationToken cancellationToken)
{
this.dctZigZag = ZigZag.CreateUnzigTable();
this.stream = stream;
this.spectralConverter = converter;
this.cancellationToken = cancellationToken;
// TODO: this is actually a variable value depending on component count
const int maxTables = 4;
this.dcHuffmanTables = new HuffmanTable[maxTables];
this.acHuffmanTables = new HuffmanTable[maxTables];
}
public unsafe void ZigZag_CreateDequantizationTable_MultiplicationShouldQuantize(int seed)
{
Block8x8F original = CreateRandomFloatBlock(-500, 500, seed);
Block8x8F qt = CreateRandomFloatBlock(0, 10, seed + 42);
var unzig = ZigZag.CreateUnzigTable();
Block8x8F zigQt = ZigZag.CreateDequantizationTable(ref qt);
Block8x8F expected = original;
Block8x8F actual = original;
ReferenceImplementations.DequantizeBlock(&expected, &qt, unzig.Data);
actual.MultiplyInplace(ref zigQt);
this.CompareBlocks(expected, actual, 0);
}
/// <summary>
/// Encodes the image with subsampling. The Cb and Cr components are each subsampled
/// at a factor of 2 both horizontally and vertically.
/// </summary>
/// <typeparam name="TPixel">The pixel format.</typeparam>
/// <param name="pixels">The pixel accessor providing access to the image pixels.</param>
private void Encode420 <TPixel>(Image <TPixel> pixels)
where TPixel : struct, IPixel <TPixel>
{
// TODO: Need a JpegScanEncoder<TPixel> class or struct that encapsulates the scan-encoding implementation. (Similar to JpegScanDecoder.)
Block8x8F b = default;
BlockQuad cb = default;
BlockQuad cr = default;
var cbPtr = (Block8x8F *)cb.Data;
var crPtr = (Block8x8F *)cr.Data;
Block8x8F temp1 = default;
Block8x8F temp2 = default;
Block8x8F onStackLuminanceQuantTable = this.luminanceQuantTable;
Block8x8F onStackChrominanceQuantTable = this.chrominanceQuantTable;
var unzig = ZigZag.CreateUnzigTable();
var pixelConverter = YCbCrForwardConverter <TPixel> .Create();
// ReSharper disable once InconsistentNaming
int prevDCY = 0, prevDCCb = 0, prevDCCr = 0;
for (int y = 0; y < pixels.Height; y += 16)
{
for (int x = 0; x < pixels.Width; x += 16)
{
for (int i = 0; i < 4; i++)
{
int xOff = (i & 1) * 8;
int yOff = (i & 2) * 4;
pixelConverter.Convert(pixels.Frames.RootFrame, x + xOff, y + yOff);
cbPtr[i] = pixelConverter.Cb;
crPtr[i] = pixelConverter.Cr;
prevDCY = this.WriteBlock(
QuantIndex.Luminance,
prevDCY,
&pixelConverter.Y,
&temp1,
&temp2,
&onStackLuminanceQuantTable,
unzig.Data);
}
Block8x8F.Scale16X16To8X8(&b, cbPtr);
prevDCCb = this.WriteBlock(
QuantIndex.Chrominance,
prevDCCb,
&b,
&temp1,
&temp2,
&onStackChrominanceQuantTable,
unzig.Data);
Block8x8F.Scale16X16To8X8(&b, crPtr);
prevDCCr = this.WriteBlock(
QuantIndex.Chrominance,
prevDCCr,
&b,
&temp1,
&temp2,
&onStackChrominanceQuantTable,
unzig.Data);
}
}
}
/// <summary>
/// Decodes the spectral scan
/// </summary>
/// <param name="frame">The image frame</param>
/// <param name="stream">The input stream</param>
/// <param name="dcHuffmanTables">The DC Huffman tables</param>
/// <param name="acHuffmanTables">The AC Huffman tables</param>
/// <param name="components">The scan components</param>
/// <param name="componentIndex">The component index within the array</param>
/// <param name="componentsLength">The length of the components. Different to the array length</param>
/// <param name="resetInterval">The reset interval</param>
/// <param name="spectralStart">The spectral selection start</param>
/// <param name="spectralEnd">The spectral selection end</param>
/// <param name="successivePrev">The successive approximation bit high end</param>
/// <param name="successive">The successive approximation bit low end</param>
public void DecodeScan(
PdfJsFrame frame,
DoubleBufferedStreamReader stream,
PdfJsHuffmanTables dcHuffmanTables,
PdfJsHuffmanTables acHuffmanTables,
PdfJsFrameComponent[] components,
int componentIndex,
int componentsLength,
ushort resetInterval,
int spectralStart,
int spectralEnd,
int successivePrev,
int successive)
{
this.dctZigZag = ZigZag.CreateUnzigTable();
this.markerBuffer = new byte[2];
this.compIndex = componentIndex;
this.specStart = spectralStart;
this.specEnd = spectralEnd;
this.successiveState = successive;
this.endOfStreamReached = false;
this.unexpectedMarkerReached = false;
bool progressive = frame.Progressive;
this.mcusPerLine = frame.McusPerLine;
this.mcu = 0;
int mcuExpected;
if (componentsLength == 1)
{
mcuExpected = components[this.compIndex].WidthInBlocks * components[this.compIndex].HeightInBlocks;
}
else
{
mcuExpected = this.mcusPerLine * frame.McusPerColumn;
}
while (this.mcu < mcuExpected)
{
// Reset interval stuff
this.mcuToRead = resetInterval != 0 ? Math.Min(mcuExpected - this.mcu, resetInterval) : mcuExpected;
for (int i = 0; i < components.Length; i++)
{
PdfJsFrameComponent c = components[i];
c.Pred = 0;
}
this.eobrun = 0;
if (!progressive)
{
this.DecodeScanBaseline(dcHuffmanTables, acHuffmanTables, components, componentsLength, stream);
}
else
{
bool isAc = this.specStart != 0;
bool isFirst = successivePrev == 0;
PdfJsHuffmanTables huffmanTables = isAc ? acHuffmanTables : dcHuffmanTables;
this.DecodeScanProgressive(huffmanTables, isAc, isFirst, components, componentsLength, stream);
}
// Reset
// TODO: I do not understand why these values are reset? We should surely be tracking the bits across mcu's?
this.bitsCount = 0;
this.bitsData = 0;
this.unexpectedMarkerReached = false;
// Some images include more scan blocks than expected, skip past those and
// attempt to find the next valid marker
PdfJsFileMarker fileMarker = PdfJsJpegDecoderCore.FindNextFileMarker(this.markerBuffer, stream);
byte marker = fileMarker.Marker;
// RSTn - We've already read the bytes and altered the position so no need to skip
if (marker >= PdfJsJpegConstants.Markers.RST0 && marker <= PdfJsJpegConstants.Markers.RST7)
{
continue;
}
if (!fileMarker.Invalid)
{
// We've found a valid marker.
// Rewind the stream to the position of the marker and break
stream.Position = fileMarker.Position;
break;
}
#if DEBUG
Debug.WriteLine($"DecodeScan - Unexpected MCU data at {stream.Position}, next marker is: {fileMarker.Marker:X}");
#endif
}
}
