[linux-audio-dev] Re: MIDI

Pieter Palmers pieterp at joow.be
Sun Nov 12 16:28:39 UTC 2006

Gene Heskett wrote:

>On Sunday 12 November 2006 06:16, Jens M Andreasen wrote:
>>On Sat, 2006-11-11 at 21:41 -0500, Gene Heskett wrote:
>>>But I like that idea, a lot.  Maybe some enterprising LAD people could
>>>get together and spec something like a midi interface running over
>>>firewire, complete with the repeaters so it can be daisy-chained just
>>>like midi can be, and hopefully release it into the PD as a new midi-2
>>>interface standard.  And design it such that it never, ever gets into
>>>the snails trail of the 31,250 baud interface it uses today.
>>MIDI over IEEE-1394 (aka firewire) exists and is spec'ed by the MMA
>>midi-consortium as an official standard. Unlike other publications from
>>the MMA, this is a free download:
>Great!  I guess I hadn't been paying attention.  Thank you very much for 
>the link.
Note that this is already implemented in FreeBob. There is nothing 
preventing us from setting up a (random number here)-channel MIDI link 
over Firewire between one or more devices.

A major issue however is discovering the devices and negotiating a 
common stream format. This is not specified by the MMA, this spec only 
describes the actual transfer of the MIDI bytes.

Another showstopper is that every sender will need his own firewire 
isochronous channel to send its data on, so that limits the number of 
devices to 16. Keep in mind that the Firewire bus is one single domain 
(for the Isochronous traffic), i.e. everybody sees everything.

When using asynchronous traffic these restrictions don't apply but then 
you lose the 'broadcast' advantage, making everything more complex.


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