mxfdemux: Incomplete support for AVCIntra essence

Submitted by Sebastian Dröge @slomo

Link to original bug (#651711)

Description

+++ This bug was initially created as a clone of Bug 650503 +++

The files with a DV stream the problems seems to be only in the duration extraction, but with the AVCIntra files the demuxer also is not able to extract the correct stream properties.

In
http://www.megaupload.com/?f=AAN8TD5U
there are some sample files

About the AVCintra issue, I have found the solution but I'm not sure.
In the function "mxf_is_mpeg_essence_track" acording to the table in the table
"SMPTE 381M 7" the key[13] value for the AVCIntra files is 0x10.

I have the pdf and this value doesn't appears, but if I add to the condition
the key->u[13] == 0x10 it works. In fact, after, when it build the
capabilities, int the "mxf_mpeg_create_caps" the 0x10 value is considered.