[linux-audio-dev] a question re: the MIDI spec

[Martijn Sipkema]

[...]
> > > > The problem here is that class compliant devices suffer bad timing
> > > > because they use bulk transfers for MIDI data. The standard for
> > > > MIDI over FireWire is much better.
[...]
> > > Is the timing really that bad?  I don't even think a firewire 8x8
> > > rackmount MIDI interface exists, so my options are kinda limited. :/
> >
> > Timing is especially bad when there is other data being transferred on
> 
> "Especially bad" is still pretty vague. What might look bad on paper might be 
> acceptable in context... 

It's not unusable, but IIRC it can get to several ms of jitter.

> > the same USB bus, as is the case with combined audio/midi interfaces.
> 
> Perhaps, but midi takes a lot less bandwidth than audio so how much worse 
> could it get? It sounds like it wouldn't be a problem if you were 
> overdubbing, but potentially in a live recording/performance if you are using 
> the audio ins for a vocal mic or whatnot.

I'm by no means an expert on this, but I think MIDI taking less bandwidth than
audio is not really relevant; it's audio data being isochronous and using a lot
of bandwidth causing the MIDI timing to suffer.

--ms