public static void readExtension(MemoryStream bb, SequenceHeader sh)
{
m_hasExtensions = true;
BitReader inb = new BitReader(bb);
int extType = inb.readNBit(4);
switch (extType)
{
case Sequence_Extension:
sh.sequenceExtension = SequenceExtension.read(inb);
break;
case Sequence_Scalable_Extension:
sh.sequenceScalableExtension = SequenceScalableExtension.read(inb);
break;
case Sequence_Display_Extension:
sh.sequenceDisplayExtension = SequenceDisplayExtension.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);
}
public static SequenceExtension read(BitReader inb)
{
SequenceExtension se = new SequenceExtension();
se.profile_and_level = inb.readNBit(8);
se.progressive_sequence = inb.read1Bit();
se.chroma_format = inb.readNBit(2);
se.horizontal_size_extension = inb.readNBit(2);
se.vertical_size_extension = inb.readNBit(2);
se.bit_rate_extension = inb.readNBit(12);
se.vbv_buffer_size_extension = inb.readNBit(8);
se.low_delay = inb.read1Bit();
se.frame_rate_extension_n = inb.readNBit(2);
se.frame_rate_extension_d = inb.readNBit(5);
return(se);
}
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 void copyExtensions(SequenceHeader sh)
{
sequenceExtension = sh.sequenceExtension;
sequenceScalableExtension = sh.sequenceScalableExtension;
sequenceDisplayExtension = sh.sequenceDisplayExtension;
}
