private PictureHeader readHeader(MemoryStream buffer)
{
PictureHeader ph = null;
MemoryStream segment;
MemoryStream fork = buffer.duplicate();
while ((segment = MPEGUtil.nextSegment(fork)) != null)
{
int code = segment.getInt() & 0xff;
if (code == MPEGConst.SEQUENCE_HEADER_CODE)
{
SequenceHeader newSh = SequenceHeader.read(segment);
if (sh != null)
{
newSh.copyExtensions(sh);
}
sh = newSh;
}
else if (code == MPEGConst.GROUP_START_CODE)
{
gh = GOPHeader.read(segment);
}
else if (code == MPEGConst.PICTURE_START_CODE)
{
ph = PictureHeader.read(segment);
}
else if (code == MPEGConst.EXTENSION_START_CODE)
{
int extType = segment.get(4) >> 4;
if (extType == SequenceHeader.Sequence_Extension || extType == SequenceHeader.Sequence_Scalable_Extension ||
extType == SequenceHeader.Sequence_Display_Extension)
{
SequenceHeader.readExtension(segment, sh);
}
else
{
PictureHeader.readExtension(segment, ph, sh);
}
}
else if (code == MPEGConst.USER_DATA_START_CODE)
{
// do nothing
}
else
{
break;
}
buffer.position(fork.position());
}
return(ph);
}
private static SequenceHeader getSequenceHeader(MemoryStream data)
{
MemoryStream segment = MPEGUtil.nextSegment(data);
while (segment != null)
{
int marker = segment.getInt();
if (marker == (0x100 | MPEGConst.SEQUENCE_HEADER_CODE))
{
return(SequenceHeader.read(segment));
}
segment = MPEGUtil.nextSegment(data);
}
return(null);
}