private void DecodePredictedFrame(Stream inStream, BitmapData currentData, BitmapData previousData, int pixelBytes)
{
int xBlocksCount = DivideRoundUp(frameWidth, MCBlockSize);
int yBlocksCount = DivideRoundUp(frameHeight, MCBlockSize);
MotionVector motionVector = MotionVector.ZERO;
for (int yBlock = 0; yBlock < yBlocksCount; yBlock++)
{
for (int xBlock = 0; xBlock < xBlocksCount; xBlock++)
{
int yStart = yBlock * MCBlockSize;
int xStart = xBlock * MCBlockSize;
// TODO: handle bad value
MCRecordType mcType = (MCRecordType)inStream.ReadUByte();
switch (mcType)
{
case MCRecordType.Identical:
DecodeTranslatedBlock(inStream, currentData, previousData, pixelBytes, yStart, xStart, MotionVector.ZERO);
break;
case MCRecordType.MotionVector:
motionVector.x = inStream.ReadSShort();
motionVector.y = inStream.ReadSShort();
DecodeTranslatedBlock(inStream, currentData, previousData, pixelBytes, yStart, xStart, motionVector);
break;
case MCRecordType.FullBlock:
DecodeFullBlock(inStream, currentData, previousData, pixelBytes, yStart, xStart);
break;
}
}
}
}
public Bitmap DecodeFrame(int frameIndex, Stream inStream)
{
if (inStream == null) return null;
try
{
// Check the frame header:
if (inStream.ReadUInt() != MAGIC_FRAME) return null;
int encodedFrameIndex = inStream.ReadSShort();
if (encodedFrameIndex != frameIndex) return null;
BitmapData currentData = currentFrame.LockBits(
new Rectangle(0, 0, frameWidth, frameHeight),
ImageLockMode.ReadOnly, currentFrame.PixelFormat);
BitmapData previousData = previousFrame.LockBits(
new Rectangle(0, 0, frameWidth, frameHeight),
ImageLockMode.ReadOnly, previousFrame.PixelFormat);
if (VisualizeMCBlockTypes)
{
debugFrame = new Bitmap(frameWidth, frameHeight, PixelFormat.Format24bppRgb);
debugFrameData = debugFrame.LockBits(
new Rectangle(0, 0, frameWidth, frameHeight),
ImageLockMode.ReadOnly, debugFrame.PixelFormat);
}
int pixelBytes = GetBytesPerPixel(currentFrame.PixelFormat);
// TODO: handle bad value
FrameType frameType = (FrameType)inStream.ReadUByte();
switch (frameType)
{
case FrameType.Intra:
DecodeIntraFrame(inStream, currentData, pixelBytes);
break;
case FrameType.Predicted:
DecodePredictedFrame(inStream, currentData, previousData, pixelBytes);
break;
}
currentFrame.UnlockBits(currentData);
previousFrame.UnlockBits(previousData);
if (VisualizeMCBlockTypes)
{
debugFrame.UnlockBits(debugFrameData);
debugFrame.Save(String.Format("debug{0:000000}.png", frameIndex), ImageFormat.Png);
debugFrame.Dispose();
}
}
catch (EndOfStreamException ex)
{
Log("Exception: {0} {1}", ex.Message, ex.StackTrace);
return null;
}
Bitmap result = currentFrame;
// double buffering
// save the current bitmap to act as previous one when decoding the next frame
SwapBitmaps(ref previousFrame, ref currentFrame);
//currentFrame.Dispose();
return result;
}