Subject: [AVT] Re: Comments (1) on draft-ietf-avt-mwpp-midi-rtp-02.txt

From: John Lazzaro <[email-masked]>
Date: Wed, 13 Mar 2002 15:38:54 -0800

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>>> Dominique Fober writes:
>>>
>>> I'm not convinced by the usefulness of interleaving MIDI commands into
>>> SysEx segments.

>> John Lazzaro writes:
>>
>>This feature seems to be getting a fair amount of negative feedback,
>>maybe its best for it to be deleted.

> Dominique Fober writes:
> You're certainly right concerning interleaving with your example
> however, my feeling is that the transmission speed on alternate
> physical layers allow to obtain the same result without
> interleaving. 

This makes sense; unless I hear objections otherwise, I'll delete
interleaving in the next revision.

---

> Dominique Fober writes:
>
> [... thoughts on pwe=1 uses of delta times ...]
>
> Wouldn't it be possible to use delta time for the
> unique purpose of expressing the sender timing intention 
> (maybe it's a fantasy). 

OK, I think I understand your concerns here. I'll try reworking the
delta-time semantics on the next document revision to address
them. 

> Of course it means that an additional mechanism to code the
> dropped F7 is to be provided (terminating the sysex with 2 
> consecutive F7 for example).

This particular solution introduces a parsing ambiguity, any trailing
0b1xxxxxxx octet patterns in a MIDI Command field need to be of known
length, in order for the variable-length delta time scheme to work --
how do we know the "second F7" isn't actually the first octet of a
multi-octet delta time?

But there are alternative solutions to this issue, I'll find one with
good properties and incorporate it into the next revision.

-------------------------------------------------------------------------
John Lazzaro -- Research Specialist -- CS Division -- EECS -- UC Berkeley
lazzaro [at] cs [dot] berkeley [dot] edu     www.cs.berkeley.edu/~lazzaro
-------------------------------------------------------------------------

_______________________________________________
Audio/Video Transport Working Group
[email-masked]
https://www1.ietf.org/mailman/listinfo/avt

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From: "Martijn Sipkema" <[email-masked]>
Date: Thu, 14 Mar 2002 13:07:22 +0100

> interleaving in the next revision.

The interleaving of MIDI system realtime commands will not
be deleted right?

> how do we know the "second F7" isn't actually the first octet of a

You are right.

> good properties and incorporate it into the next revision.

It will have to be terminated, perhaps using some other status byte
then 0xf7 (0xf0?).

--martijn