Ethereal-dev: RE: [Ethereal-dev] Building mpeg-4 dissector, help.

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From: "Simon Hailstone" <Simon.Hailstone@xxxxxxxxxxxxxxxxxxx>
Date: Tue, 2 Mar 2004 17:14:35 -0000
>> I don't know so much about the details in MPEG-4 and if
>> it is possible to make a heuristic dissector  for it,
>> i.e. if there is something in the RTP payload that is
>> very specific for MPEG-4. 

> There is actually a bit sequence that is unique in an mpeg4
> elementary video stream that is called start code.  This
> code is a 32bit sequence composed of 23 0 and a 1 (0000 0000
> 0000 0000 0000 0001).The next 8 bits are to determine the
> type of content of the video stream (VOPs, GVOPs, SPRITEs ecc.)
> So totally there are 32bits that determines the RTP payload
> in an unique way.
>
> Would this be enough to accomplish a heuristic dissection?


That would match MPEG-2 video Elementary Streams too, since
they also use 0x00000001 for start codes...


Regards

Simon Hailstone
Quixotic Research