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-   -   Best MIDI Input solution for iPad? (https://www.propellerheads.se/forum/showthread.php?t=178307)

vanKloot 2013-03-16 00:52

Best MIDI Input solution for iPad?
 
So now that R7 has MIDI, I'm seriously thinking of starting to use my iPad as an external synth module.

What do folks use to do MIDI with their iPads currently? I've played a little bit with RsTouch using Network MIDI and it seems to work, but that's just for mixer control, not note data or anything more complex.

Thanks for any input!

normen 2013-03-16 00:54

The "Camera Connection Kit" includes a USB adapter for the iPad. Its compatible to most MIDI devices that work without a driver (USB-MIDI standard), like for example the inexpensive "USB Midi Cables" you get. The "iRig MIDI" thingy is proprietary and doesn't use apples normal MIDI stack, so your app has to support it explicitly.

drk1 2013-03-16 13:39

Quote:

Originally Posted by vanKloot (Post 1263037)
So now that R7 has MIDI, I'm seriously thinking of starting to use my iPad as an external synth module.

What do folks use to do MIDI with their iPads currently? I've played a little bit with RsTouch using Network MIDI and it seems to work, but that's just for mixer control, not note data or anything more complex.

Thanks for any input!

Actually rsTouch is pretty demanding on a MIDI set up. The amount of MIDI data that flows between the iPad and Reason can at times use much of a single MIDI cable's available data bandwidth. rsTouch is managing hundreds of parameters, each of which uses a unique MIDI command. These commands are represented by the entire range of possible MIDI commands: notes, aftertouch, control changes, pitch bend, and SYSEX. In other words its a pretty good "stress test" for a MIDI connection.

Generally speaking a network MIDI connection on a good Wi-Fi connection (especially an ad hoc set up) performs on par with a typical iPad USB MIDI solution. Also not all USB MIDI interfaces offer the same performance, and some actually have surprising latency. In those cases a network MIDI connection may actually be a better method.

Another consideration is that when sending from Reason to the iPad, for example controlling an iPad synth, a USB MIDI connection will encounter delay leaving the computer and additional delay at the iPad, both due to the USB MIDI driver delay as well as any delays internal to the MIDI interfaces. So the total delay is more than you'd normally expect from a "simple MIDI cable". There is of course always sending and receiving delay but hardware devices, like synthesizers, usually have optimized their MIDI I/O for responsiveness.

Finally iPad apps themselves have a broad range of "MIDI responsiveness". Some synths and controllers do this better than others. What may seem to be poor MIDI connection performance may just end up being a limitation in the app itself.

Bottom line is that its not a given that a USB MIDI connection between your computer and your iPad will perform with lower latency, and handle more throughput, than the network MIDI connection. My recommendation would be to really give network MIDI a good go before committing to a wired-MIDI configuration.

normen 2013-03-16 13:49

No, for instruments the MIDI wifi latency is definitely feelable. You just can't compare network UDP packets with a direct over USB protocol. Agree on most other things though :)

BoddAH 2013-03-16 14:39

Quote:

Originally Posted by normen (Post 1263525)
No, for instruments the MIDI wifi latency is definitely feelable. You just can't compare network UDP packets with a direct over USB protocol. Agree on most other things though :)

I use CoreMIDI over WiFi.

I had some terrible latency and jitter issues when I was doing this over my standard router home network (unusable for actual performance/note data) but all these issues disappear if you set up an Ad Hoc network between your computer and the iOS devices and everything's tight and in sync.

normen 2013-03-16 14:41

Quote:

Originally Posted by BoddAH (Post 1263564)
I use CoreMIDI over WiFi.

I had some terrible latency and jitter issues when I was doing this over my standard router home network (unusable for actual performance/note data) but all these issues disappear if you set up an Ad Hoc network between your computer and the iOS devices and everything's tight and in sync.

I played around a lot with it and theres no way to make a drummer be pleased with the WiFi setup to play any percussion instrument. WiFi is unreliable per se, its kind of the trick about it ;)

Dogboy1973 2013-03-16 16:24

I use an IK iRig MIDI interface. Works very well for getting MIDI in and out of the iPad ;)

drk1 2013-03-16 16:30

Quote:

Originally Posted by normen (Post 1263525)
No, for instruments the MIDI wifi latency is definitely feelable. You just can't compare network UDP packets with a direct over USB protocol. Agree on most other things though :)

This is a good discussion!

I agree that an ideal wired MIDI setup will have less latency than an ideal network MIDI setup. And a knowledgeable user with the means can, if they wish, construct a wired MIDI set up that has less latency than a network MIDI one in the real world. However its not a given that a iPad connected to a computer using wired MIDI will always be lower latency, or better performing, under typical sequencer loads. A lot depends on the specifics of the wired MIDI approach, and for some users (who have not looked at this in the same technical depth you have) there needs to be an awareness that there are a lot of "shades of gray" when comparing network MIDI and using USB MIDI with an iPad.

The problem is that a typical USB MIDI interface that works with the iPad can vary from "good performing" to very poor performing. Some have relatively long inherent delays just getting the MIDI into the iPad, before CoreMIDI even takes it. In some cases this can be worse than a high quality ad hoc Wi-Fi connection. Also how much data needs to be passed plays a big part. Playing a monophonic synth line or some simple three note chords is not likely to tax the USB MIDI set up. Trying to send a song's MIDI data driving a hardware drum machine, two synths, and an iPad instrument is another matter. So the answer really does depend on intended usage, and the specific USB interfaces. (Hint: avoid inexpensive "USB MIDI cables"). Unfortunately the only way to know is to test.

My other point is that the iPad app itself often is a contributor to the delay. But since many users only use network MIDI to connect their iPads it is easy for them to assume that any delay comes from the "slow" network MIDI connection. They might see that its actual the app if they tried using it with a top-notch wired-MIDI connection. So again the only way to know is to compare using some type of MIDI latency test.

So like you say we agree on most of these matters. I especially agree with your comment about percussion players. Then again many of those have issue with wired MIDI timing jitter and latency :-)

normen 2013-03-16 16:38

Quote:

Originally Posted by drk1 (Post 1263687)
This is a good discussion!

I agree that an ideal wired MIDI setup will have less latency than an ideal network MIDI setup. And a knowledgeable user with the means can, if they wish, construct a wired MIDI set up that has less latency than a network MIDI one in the real world. However its not a given that a iPad connected to a computer using wired MIDI will always be lower latency, or better performing, under typical sequencer loads. A lot depends on the specifics of the wired MIDI approach, and for some users (who have not looked at this in the same technical depth you have) there needs to be an awareness that there are a lot of "shades of gray" when comparing network MIDI and using USB MIDI with an iPad.

The problem is that a typical USB MIDI interface that works with the iPad can vary from "good performing" to very poor performing. Some have relatively long inherent delays just getting the MIDI into the iPad, before CoreMIDI even takes it. In some cases this can be worse than a high quality ad hoc Wi-Fi connection. Also how much data needs to be passed plays a big part. Playing a monophonic synth line or some simple three note chords is not likely to tax the USB MIDI set up. Trying to send a song's MIDI data driving a hardware drum machine, two synths, and an iPad instrument is another matter. So the answer really does depend on intended usage, and the specific USB interfaces. (Hint: avoid inexpensive "USB MIDI cables"). Unfortunately the only way to know is to test.

My other point is that the iPad app itself often is a contributor to the delay. But since many users only use network MIDI to connect their iPads it is easy for them to assume that any delay comes from the "slow" network MIDI connection. They might see that its actual the app if they tried using it with a top-notch wired-MIDI connection. So again the only way to know is to compare using some type of MIDI latency test.

So like you say we agree on most of these matters. I especially agree with your comment about percussion players. Then again many of those have issue with wired MIDI timing jitter and latency :-)

Yes, totally. I played with the iOS MIDI stack myself and you have to implement relatively basic things like note triggering etc. yourself. Plenty of chances to mess things up and just increase the latency here and there, I agree. E.g. some applications definitely seem to "quantize" according to screen refresh rate (sigh).
Also the audio latency will probably play the most important role for most, like you say. I was plainly talking about the MIDI connection itself. If you want a "normal" MIDI experience like on PC for instruments, use a direct cable. For remotes and the occasional chord input the WiFi connection is completely fine. With AdHoc even for melody.. But for percussion.. Well if you can play with it you are definitely not a very groovy percussionist ;)

vanKloot 2013-03-16 16:50

Very interesting gang, thanks for the details. This has revealed much that I didn't know about network/Wifi MIDI!


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