Re: [AH] Alternatives to the UM-880 USB-MIDI interface?

From codemechanic
Sent Sat, Dec 22nd 2018, 05:44

A year or two ago I decided to gear up on reliable midi interfaces and
went hunting for old Unitor 8s and MTP AV (both USB and ADB) units. I
went as far as bring up my old PowerMac 9600 running Mac OS 9.1 in an
attempt to find the latest firmware revision for the Unitor8. I was
way out in the weeds when a friend made the timely recommendedation
that I should check out the iConnetivity Mio-10.

I haven't completely put them through their paces yet, but I now own
two Mio-10s and am super happy with them so far. Despite having a good
amount of outboard gear I've been composing in-the-box these days.
With the Mio-10s I've really just done the bare minimum (upgraded
firmwware, sent sysex to and from a few synths, and set up some basic
Midi routing etc).

Two important things they do:
- work without needing to be connected to a computer
- support midi over ethernet (RTP Midi) - USB not required

Here's more information on RTP Midi, aka AppleMIDI:
https://en.wikipedia.org/wiki/RTP-MIDI

RTP Midi has been around for many moons and was released as a part of
Mac OS X v10.4 Tiger. There's an RFC for RTP Midi
(https://tools.ietf.org/html/rfc6295), and it has support for both
Midi timestamps and latency compensation. The wikipedia page states
average latency of 1-2ms with the possibility of hitting 125
microseconds under optimal conditions. Here is some additional
information on RTP Midi in regards to latency:
https://en.wikipedia.org/wiki/RTP-MIDI#Latency

Back to the older USB units... I've run the Unitor 8 under Mac OS X
Sierra and everything works fine (same with the MTP AV for that
matter). The latest Unitor Family Driver 2.5 is still available on
Apple's website. I can't recall the exact process but if you don't
have it installed already and you launch Logic with your
Unitor8/AMT8/MT4 interface plugged in, you should be prompted to
download and install the 2.5 driver.

Unitor Family Driver 2.5
https://support.apple.com/kb/DL991

Most of the iConnectivity devices (PlayAUDIO12, MIDI4+, mio4, mio10)
come equipped with a LAN port and support RTP Midi. Here's a some
additional information:
https://www.iconnectivity.com/blog/2018/3/1/midi-over-ethernet-the-marvel-o=
f-rtp-midi

iConnectivity has their own driver for Windows 7 and above:
https://www.iconnectivity.com/windows-drivers

And here's another RTP Midi driver for Windows XP through Windows 10:
https://www.tobias-erichsen.de/software/rtpmidi.html

And ofcourse there are tons of other implementations of RTP Midi under
other OSes and languages including Linux, iOS, Arduino, etc.

Not my intention, but now that I've made this sound like an
iConnectivity sales pitch I'll reiterate that my experience with their
product and their company has been great.

Given that I have a few MTP AV, Unitor 8, and Mio 10s with various
firmware revisions, as well as a few Mac and Windows boxes, I'd be
open to doing a Midi timing shootout. That's assuming that someone
hasn't done a better one yet. I did find reference to a Windows
application called MidiTest that seems like it could come in handy -
unfortunately the domain isn't around anymore:
http://web.archive.org/web/20100217060619/http://earthvegaconnection.com/ev=
c/products/miditest/index.html#download

MidiMonitor perhaps?
https://www.snoize.com/MIDIMonitor/

-Ben


On Fri, Dec 21, 2018 at 6:28 PM Jason Proctor <xxxxx@xxxxxxx.xxx> wrote:
>
> no it's my fault for not being clearer.
>
> idk whether the AMT-8 works with the class compliant drivers included
> with OS X. i've always used a driver specific to the AMT and Unitor.
> also idk whether the send-ahead feature works as i don't use Logic and
> don't know whether Live implements it (i suspect not).
>
>
> On Fri, Dec 21, 2018 at 6:02 PM Brian Willoughby
> <xxxxxx@xxxxxxxxxxxx.xxx> wrote:
> >
> > Hmm, I didn=E2=80=99t see anything specific to CoreMIDI, custom drivers=
, or the send-ahead features.
> >
> > Florian said, =E2=80=9Cworks like charm=E2=80=9D - but I assumed that w=
as using the standard USB-MIDI Class compliant driver that is built in to m=
acOS and which works with all USB-MIDI Devices.
> >
> > Your messages raised more questions about this elusive feature than the=
y answered - other than assurance that the AMT-8 has basic functionality.
> >
> > Maybe I lost some messages with more details.
> >
> > Brian
> >
> >
> > On Dec 21, 2018, at 4:53 PM, Jason Proctor <xxxxx@xxxxxxx.xxx> wrote:
> > > as Florian and I mentioned earlier in the thread, the current AMT-8
> > > driver works fine with later operating systems. (Sierra, here, at
> > > least.)
> > >
> > > and yes anyone can take advantage of send-ahead timestamping, but
> > > whether they do is another matter :-)
> > >
> > > On Fri, Dec 21, 2018 at 4:49 PM Brian Willoughby wrote:
> > >> AMT-8 support would require a CoreMIDI driver from Emagic or Apple. =
Whether CoreMIDI has changed since such a driver was written, and whether i=
t would still work on a modern OS is the real question. I=E2=80=99m not awa=
re of any significant changes to CoreMIDI that orphaned any prior drivers, =
but I=E2=80=99m also not aware of whether the AMT-8 ever had a CoreMIDI dri=
ver.
> > >>
> > >> At any rate, if there is a CoreMIDI driver then all CoreAudio MIDI s=
oftware would be able to take advantage of Advanced MIDI Transmitter featur=
es. That=E2=80=99s the beauty of CoreMIDI: They managed to implement send-a=
head timestamping in a way that=E2=80=99s not specific to any particular ha=
rdware implementation. Of course, not all apps take advantage of this, but =
those that do shouldn=E2=80=99t be tied to any particular hardware.
> > >>
> > >> If anybody has more information, then please share. I remember stron=
gly considering the AMT-8 for its features, but settled on the MOTU MTP-AV =
=E2=80=9CMIDI timepiece=E2=80=9D with SMPTE. Not that I=E2=80=99ve actually=
 used the thing in decades...
> > >>
> > >> Brian
> > >>
> > >>
> > >> On Dec 7, 2018, at 9:43 AM, Jason Proctor wrote:
> > >>> fwiw, the Emagic AMT-8 and Unitor interfaces implemented send-ahead
> > >>> timestamping way back when (hence the name Advanced MIDI Transmitte=
r).
> > >>>
> > >>> not sure whether any drivers or apps still support it (maybe Logic =
as
> > >>> previously described)
> > >>>
> > >>>> From: Bruno Afonso
> > >>>> Date: 7 December 2018 at 13:56:56
> > >>>> To: Brian Willoughby
> > >>>> Cc: Analog Heaven, Jason Proctor
> > >>>>
> > >>>> Brian is right, what is nice about the motu stuff is their timesta=
mping. Drivers can be finicky at times. I'm curious to know about the timin=
g of the newer mio offerings... with a uC or smart oscilloscope one could p=
roperly test these. I don't have a mio...
> > >>>>
> > >>>> On Tue, Dec 4, 2018, 22:56 Brian Willoughby, wrote:
> > >>>>>
> > >>>>> Apple has USB-MIDI Class compliant drivers fully sorted. Apple im=
plement every aspect of the specification, where Microsoft Windows versions=
 fall short. I know this because I have designed USB-MIDI hardware and foun=
d out the hard way where the OS support for the USB-MIDI specification stop=
s.
> > >>>>>
> > >>>>> For my clients, I deliver firmware that supports Windows, because=
 it=E2=80=99s a market necessity. Unfortunately, that requires dumbing down=
 the feature set to the short list supported by Microsoft. For my personal =
control surfaces and MIDI interfaces, I use firmware that takes full advant=
age of USB-MIDI capabilities, even though these devices only work with Mac =
OS X.
> > >>>>>
> > >>>>>
> > >>>>> That said, even the USB-MIDI specification is severely lacking. I=
t provides no timing information, so precise timing of MIDI events is very =
sloppy. This is a shortcoming of the specification itself.
> > >>>>>
> > >>>>> What you=E2=80=99re witnessing is that manufacturers like Roland =
and MOTU are trying to improve on USB-MIDI by providing a non-class-complia=
nt implementation that adds the missing precision. The problem here is that=
 there is no standard for decent MIDI time stamping, so there=E2=80=99s no =
way for an OS to ship a class compliant driver. The result is that users mu=
st download drivers from the manufacturer and install them before things wi=
ll work well. That=E2=80=99s a difficult task when operating systems are co=
nstantly changing, so I=E2=80=99m not really surprised that hardware vendor=
s sometimes fall behind.
> > >>>>>
> > >>>>>
> > >>>>> Note that there is a standard for better-than-USB-MIDI performanc=
e on macOS. It falls under the umbrella of Apple=E2=80=99s CoreMIDI. Thanks=
 to CoreMIDI, applications like Logic can access the precise timing of MOTU=
 MTS (MIDI Time Stamping), and presumably whatever it is that Roland has to=
 get beyond the limitations of USB-MIDI. Applications do not need to be awa=
re of hardware specifics, or variations in the USB protocol additions. As l=
ong as they support CoreMIDI, and as long as the hardware manufacturers pro=
vide CoreMIDI drivers in addition to their USB drivers, everything works.
> > >>>>>
> > >>>>> What this means is the Logic can read ahead in your MIDI sequence=
 file, deliver the data to the MIDI interface ahead of time in a way that c=
ircumvents any bandwidth bottlenecks, and then the shared time reference al=
lows the MIDI interface to transmit the MIDI data at the precise time it wa=
s authored for. In the other direction, incoming MIDI is marked with a time=
 stamp that is then delivered to the application via CoreMIDI in a way that=
 preserves sub-millisecond accuracy. The caveat is that you cannot improve =
real-time passthrough of MIDI data because there=E2=80=99s no looking ahead=
, and thus any bottlenecks in bandwidth necessarily introduce latency. In t=
his latter case, you=E2=80=99re better off doing MIDI overdubs, with separa=
te record and playback passes, rather than attempting to do real-time MIDI =
manipulation.
> > >>>>>
> > >>>>> For the technical reasons described above, I recommend MOTU (Mark=
 of the Unicorn) MIDI interfaces that feature MTS (MIDI Time Stamping). You=
 need to make sure that you install the custom drivers, but it=E2=80=99s th=
e only system that doesn=E2=80=99t have serious flaws. (I=E2=80=99ve yet to=
 evaluate Roland=E2=80=99s improvements, so perhaps they=E2=80=99re on par)
> > >>>>>
> > >>>>> Brian Willoughby
> > >>>>>
> > >>>>> On Dec 4, 2018, at 11:02 AM, Jason Proctor wrote:
> > >>>>>> still a little disappointed that operating systems didn't get MI=
DI sorted ages ago and we still have driver compatibility nonsense happenin=
g this far down the line (and i say this as a developer).



--
benjamin allen
xxxxxxxxxxxx@xxxxx.xxx
415.624.9111
http://www.codemechanic.com