Author: ods15 Date: Sat Oct 28 20:14:40 2006 New Revision: 164 Modified: trunk/docs/nut-english.txt Log: explanation of NUT packets Modified: trunk/docs/nut-english.txt ============================================================================== --- trunk/docs/nut-english.txt (original) +++ trunk/docs/nut-english.txt Sat Oct 28 20:14:40 2006 @@ -29,6 +29,20 @@ beginning from 0. This allows simple and compact reference to streams in packet types where overhead must be kept to a minimum. +Packet Structure + +Every NUT packet has a packet_header and a packet_footer. +The packet_header consists of a 64-bit startcode, a forward_ptr, and an +optional CRC on the packet header if the forward_ptr is larger than 4k. +The forward_ptr gives the size of the packet from after the packet_header +until the end of the packet_footer. The optional CRC is to prevent a +demuxer from seeing a damaged startcode and forward_ptr with a high size, +causing it to skip or buffer a large part of the file, only to find it is +not really a NUT packet. +The packet_footer consists of reserved_bytes, which is room for any +reserved fields which can be skipped by old demuxers, and a CRC covering +the packet from after the packet_header until the CRC itself. + Header Structure A NUT file must begin with a magic identification string, followed by