From Jason Proctor Sent Sat, Dec 22nd 2018, 02:26
From Jason Proctor Sent Sat, Dec 22nd 2018, 02:26
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 was= using the standard USB-MIDI Class compliant driver that is built in to mac= OS and which works with all USB-MIDI Devices. > > Your messages raised more questions about this elusive feature than they = 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. Wh= ether CoreMIDI has changed since such a driver was written, and whether it = would still work on a modern OS is the real question. I=E2=80=99m not aware= of any significant changes to CoreMIDI that orphaned any prior drivers, bu= t I=E2=80=99m also not aware of whether the AMT-8 ever had a CoreMIDI drive= r. > >> > >> At any rate, if there is a CoreMIDI driver then all CoreAudio MIDI sof= tware would be able to take advantage of Advanced MIDI Transmitter features= . That=E2=80=99s the beauty of CoreMIDI: They managed to implement send-ahe= ad timestamping in a way that=E2=80=99s not specific to any particular hard= ware implementation. Of course, not all apps take advantage of this, but th= ose that do shouldn=E2=80=99t be tied to any particular hardware. > >> > >> If anybody has more information, then please share. I remember strongl= y 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 Transmitter)= . > >>> > >>> 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 timestamp= ing. Drivers can be finicky at times. I'm curious to know about the timing = of the newer mio offerings... with a uC or smart oscilloscope one could pro= perly 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 impl= ement every aspect of the specification, where Microsoft Windows versions f= all short. I know this because I have designed USB-MIDI hardware and found = out the hard way where the OS support for the USB-MIDI specification stops. > >>>>> > >>>>> For my clients, I deliver firmware that supports Windows, because i= t=E2=80=99s a market necessity. Unfortunately, that requires dumbing down t= he feature set to the short list supported by Microsoft. For my personal co= ntrol surfaces and MIDI interfaces, I use firmware that takes full advantag= e of USB-MIDI capabilities, even though these devices only work with Mac OS= X. > >>>>> > >>>>> > >>>>> That said, even the USB-MIDI specification is severely lacking. It = provides no timing information, so precise timing of MIDI events is very sl= oppy. This is a shortcoming of the specification itself. > >>>>> > >>>>> What you=E2=80=99re witnessing is that manufacturers like Roland an= d MOTU are trying to improve on USB-MIDI by providing a non-class-compliant= implementation that adds the missing precision. The problem here is that t= here is no standard for decent MIDI time stamping, so there=E2=80=99s no wa= y for an OS to ship a class compliant driver. The result is that users must= download drivers from the manufacturer and install them before things will= work well. That=E2=80=99s a difficult task when operating systems are cons= tantly changing, so I=E2=80=99m not really surprised that hardware vendors = sometimes fall behind. > >>>>> > >>>>> > >>>>> Note that there is a standard for better-than-USB-MIDI performance = on macOS. It falls under the umbrella of Apple=E2=80=99s CoreMIDI. Thanks t= o CoreMIDI, applications like Logic can access the precise timing of MOTU M= TS (MIDI Time Stamping), and presumably whatever it is that Roland has to g= et beyond the limitations of USB-MIDI. Applications do not need to be aware= of hardware specifics, or variations in the USB protocol additions. As lon= g as they support CoreMIDI, and as long as the hardware manufacturers provi= de CoreMIDI drivers in addition to their USB drivers, everything works. > >>>>> > >>>>> What this means is the Logic can read ahead in your MIDI sequence f= ile, deliver the data to the MIDI interface ahead of time in a way that cir= cumvents any bandwidth bottlenecks, and then the shared time reference allo= ws the MIDI interface to transmit the MIDI data at the precise time it was = authored for. In the other direction, incoming MIDI is marked with a time s= tamp that is then delivered to the application via CoreMIDI in a way that p= reserves sub-millisecond accuracy. The caveat is that you cannot improve re= al-time passthrough of MIDI data because there=E2=80=99s no looking ahead, = and thus any bottlenecks in bandwidth necessarily introduce latency. In thi= s latter case, you=E2=80=99re better off doing MIDI overdubs, with separate= record and playback passes, rather than attempting to do real-time MIDI ma= nipulation. > >>>>> > >>>>> For the technical reasons described above, I recommend MOTU (Mark o= f the Unicorn) MIDI interfaces that feature MTS (MIDI Time Stamping). You n= eed to make sure that you install the custom drivers, but it=E2=80=99s the = only system that doesn=E2=80=99t have serious flaws. (I=E2=80=99ve yet to e= valuate 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 MIDI= sorted ages ago and we still have driver compatibility nonsense happening = this far down the line (and i say this as a developer).