private static int numberOfFrameCentreOffsets(SequenceExtension se, PictureCodingExtension pce)
{
if (se == null || pce == null)
{
throw new ArgumentException("PictureDisplayExtension requires SequenceExtension"
+ " and PictureCodingExtension to be present");
}
if (se.progressive_sequence == 1)
{
if (pce.repeat_first_field == 1)
{
if (pce.top_field_first == 1)
{
return(3);
}
else
{
return(2);
}
}
else
{
return(1);
}
}
else
{
if (pce.picture_structure != PictureCodingExtension.Frame)
{
return(1);
}
else
{
if (pce.repeat_first_field == 1)
{
return(3);
}
else
{
return(2);
}
}
}
}
public static void readExtension(MemoryStream bb, PictureHeader ph, SequenceHeader sh)
{
ph.m_hasExtensions = true;
BitReader inb = new BitReader(bb);
int extType = inb.readNBit(4);
switch (extType)
{
case Quant_Matrix_Extension:
ph.quantMatrixExtension = QuantMatrixExtension.read(inb);
break;
case Copyright_Extension:
ph.copyrightExtension = CopyrightExtension.read(inb);
break;
case Picture_Display_Extension:
ph.pictureDisplayExtension = PictureDisplayExtension.read(inb, sh.sequenceExtension,
ph.pictureCodingExtension);
break;
case Picture_Coding_Extension:
ph.pictureCodingExtension = PictureCodingExtension.read(inb);
break;
case Picture_Spatial_Scalable_Extension:
ph.pictureSpatialScalableExtension = PictureSpatialScalableExtension.read(inb);
break;
case Picture_Temporal_Scalable_Extension:
ph.pictureTemporalScalableExtension = PictureTemporalScalableExtension.read(inb);
break;
default:
throw new Exception("Unsupported extension: " + extType);
}
}
public static PictureDisplayExtension read(BitReader bits, SequenceExtension se, PictureCodingExtension pce)
{
PictureDisplayExtension pde = new PictureDisplayExtension();
pde.frame_centre_offsets = new Point[numberOfFrameCentreOffsets(se, pce)];
for (int i = 0; i < pde.frame_centre_offsets.Length; i++)
{
int frame_centre_horizontal_offset = bits.readNBit(16);
bits.read1Bit();
int frame_centre_vertical_offset = bits.readNBit(16);
bits.read1Bit();
pde.frame_centre_offsets[i] = new Point(frame_centre_horizontal_offset, frame_centre_vertical_offset);
}
return(pde);
}
