Wireshark-bugs: [Wireshark-bugs] [Bug 4455] AppleMIDI - dissector for lightweight session protoc
https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=4455
--- Comment #8 from Tobias Erichsen <t.erichsen@xxxxxx> 2010-02-07 18:05:54 PST ---
(In reply to comment #5)
> Can you provide a pointer to a document with details about the
> "Apple Network-Midi Session Protocol".
I'm not sure if I can distribute that document, I will possibly
check about that...
> 1. The AppleMidi SeqNum is being shown as 4 bytes big-endian aka network order;
> The RTP sequence number is being shown as the hi-order (ie first_ two bytes
> of the AppleMidi SeqNum (again in big-endian aka network order).
> Is this correct ?
The document specifies it as a 32bit value, but the meaningful part is only
16bit wide, I got confirmation of that just today.
> 2. In any case, the 16 bit "ack" sequence number in the data in frame #30
> doesn't match the RT-Sequence number in frame #29. (The hi-order two bytes seem
> to be in little-endian rather than big-endian format).
> Is the sequence number in the frame incorrect ?
Actually it is not. That response is sent from a small external device
that is compatible to the AppleMIDI protocol, but I already discovered
that flaw in their implementation and I already notified the company
about it.
> I note, however, that the "ack" in frame #78 *does* match the RT-Sequence # in
> frame #77.
>From the MAC-address you can see that this packet is actually the one that
Apple sends - and which is in the right format.
Best regards,
Tobias
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