Subject: Re: [linux-audio-dev] a question re: the MIDI spec
From: John Check (j4strngs_AT_bitless.net)
Date: Fri Sep 10 2004 - 21:38:59 EEST
On Friday 10 September 2004 02:07 pm, Martijn Sipkema wrote:
> > On Fri, 2004-09-10 at 07:49, Martijn Sipkema wrote:
> > > >> [...] the USB specification. And it even appears like some vendors
> > > >> are (finally!) starting to follow suit:
> > > >>
> > > >> http://midiman.com/products/en_us/KeystationPro88-main.html
> > > >>
> > > >> - "USB class compliant-no drivers required for
> > > >> Windows XP or Mac OS X"
> > > >
> > > > M-Audio started following suit only after they hung their engineers
> > > > with a USB cable and bought Evolution who had always made
> > > > class-compliant devices.
> > >
> > > 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.
> >
> > Hmm.. I'm just about to drop $400 on a USB MIDI interface (Edirol
> > UM-880), so that's not something I want to hear!
> >
> > 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...
> 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.
> There are several USB interfaces that don't use the standard
> MIDI-over-USB protocol, but I don't think information about these
> protocols is available.
>
> Perhaps there are interfaces that support both the standard protocol and
> one with better timing...
>
> --ms
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