Wireshark-bugs: [Wireshark-bugs] [Bug 12490] Incorrect decode of 1394 dissection as part of 1722
Comment # 4
on bug 12490
from Paul
Anders,
It is Simple Video Format
0x00 - 61883/IIDC
0x01 - MMA over AVTP
0x02 - Simple Audio Format
0x03 - Simple Video Format
0x02 and 0x03 are referenced in 1722A. I see from packet-ieee1722a.c that only
the audio types are dissected currently. Hence the problem I am seeing, so not
a bug but intention.
Another point is that the standard publication seems to be in limbo. The
previous version is superseded but the current draft is not released.
I guess this ticket should be parked until the latest spec is released then
this can be a feature request at some point.
Paul
(In reply to Anders Broman from comment #3)
> (In reply to Paul from comment #2)
> > Alexis,
> >
> > I'm far from an expert either but I did buy the spec. Unfortunately it's
> > not so enlightening either. Apart from the comment that 00 represents no
> > CIP header it does not include an example of this. I haven't been able to
> > find any examples either. I do have some sample code that reconstructs the
> > camera data so I am reverse engineering that at the moment to find out what
> > should be going on. It certainly looks like the the data payload commences
> > immediately after the 1394 header without the CIP header. I haven't yet
> > decoded the payload (rebuild a jpg image) but as soon as I have done that I
> > will be able to confirm for sure the correct dissection. I will post an
> > update as soon as I get the definitive information.
> > (In reply to Alexis La Goutte from comment #1)
> > > Hi Paul,
> > >
> > > Can you explain the "good" dissection needed ? (i no a expert on 1722
> > > stuff... and the spec are not available...
> This link
> http://avnu.org/wp-content/uploads/2014/05/AVnu-AAA2C_Audio-Video-Transport-
> Protocol-AVTP_Dave-Olsen.pdf
>
> Has some pictures of the header layout
> What does the standard say about the subtype field, the link only gives:
>
> AVTP subtype field specifies streaming protocol
>
> 00 61883_IIDC IEC 61883/IIDC over AVTP
> 01 MMA MMA payload over AVTP
> :
> e.g 3 is not listed
>
> Regards
> Anders
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