Author: ods15
Date: Sat Oct 28 20:29:06 2006
New Revision: 165
Modified:
trunk/docs/nut-english.txt
Log:
Explain VLC's...
Modified: trunk/docs/nut-english.txt
============================================================
==================
--- trunk/docs/nut-english.txt (original)
+++ trunk/docs/nut-english.txt Sat Oct 28 20:29:06 2006
 -43,6
+43,20
reserved fields which can be skipped by old demuxers, and a
CRC covering
the packet from after the packet_header until the CRC
itself.
+Variable Length Coding
+
+Almost all fields in NUT are coded using VLCs. VLCs allow
for compact
+storage of small integers, which still being extendible to
infinitely
+large integers. The syntax is of a VLC is, per byte, a 1
bit flag stating
+if there are more bits to the integer, and 7 bits to be
prepended to the
+lsb of the integer, shifting the previous value to the
left.
+Stuffing is allowed in VLCs by adding 0x80 bytes before the
actual value,
+but a maximum of 8 bytes of stuffing is allowed in any VLC
outside of a
+NUT packet. The only such fields are forward_ptr and fields
in frame
+headers. This is to prevent demuxers from looping on a
large of amount of
+damaged bytes of 0x80. Fields inside a NUT packet are
protected by a CRC
+whcih can be checked before decoding.
+
Header Structure
A NUT file must begin with a magic identification string,
followed by
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