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Device Linking woes

Started by robbaron, July 03, 2014, 03:25:12 PM

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Quote from: bassman on August 27, 2014, 03:25:56 PM
arlo: Send & follow used to work before version 4.

This functionality didn't change in version 4, but I'll test it again.


I could be wrong as we just discovered the remote option just prior to v4 release. I do remember a device not being greyed out if it was already set to following. This seams to be new in v4.


Now that I think of it, I'm pretty sure the device grayed out means there is some kind of connection problem. I see that occasionally when testing, but I don't know what causes it. (The connection menu comes from an iOS framework that I don't control.) If the device is not set up to be followed, it wouldn't appear in the menu at all.


Quote from: bassman on August 27, 2014, 03:25:56 PMChristoph: Thanks for the reply.  I was a little worried the WIFI option would not work well either.  I was just about to spring for MIDI bridge to test so I am glad you answered when you did.  Does song selection work very well using MIDI interfaces & cables?  Do you just send and receive MIDI song numbers?  Can anyone in the group send them and the others follow or do you need to have only one device sending?  Would like to know this works before spending cash on 3 interfaces & cables.

We do use MIDI a lot, but not for device linking. We actually had a few shows with MIDI over WiFi and Bluetooth device linking - but this turned out to be not very reliable. It might have to do with our special stage setup, that has additional WiFi networks running for video and mixer remote control and also wireless digital guitar transmitters that have to share the 2.4 GHz band with WiFi and Bluetooth. Please see this topic for more info. I would suggest you give it a try with the MIDI Bridge app. And if all works, but you have connection problems occasionally, I would go for the hardware interfaces. However, there might be two possible show stoppers for your planned setup:

  • For more than two devices in the group sending and receiving MIDI data, you would need to merge MIDI inputs: E.g. device 1 would have to receive from 2 and 3 simultaneously. Because MIDI is rather a one-way serial connection, this could be really difficult to implement. You would need MIDI interfaces with more than one input or additional hardware mergers. But you can implement this virtually with CoreMIDI and the MIDI Bridge app.
  • You would have to be really careful to not create endless loops of MIDI data: E.g. device 1 sends a MIDI song select command that switches to a song on device 2 but also lets device 2 send a song selection command back and so on. When I used this setup, I had a "master" and a "slave" device where this was not a problem. But with all devices as "master" and slave" simultaneously, you probably would need to differentiate if the song select action was triggered by the user or by an incoming MIDI message and prevent the sending of MIDI song select messages in the latter case. I am not sure how Arlo has implemented this.


Quote from: Christoph on August 28, 2014, 04:30:00 AM
You would have to be really careful to not create endless loops of MIDI data: E.g. device 1 sends a MIDI song select command that switches to a song on device 2 but also lets device 2 send a song selection command back and so on.

When the app is used for the Bluetooth device linking, it will not send a song selection message as a result of receiving a song selection message, to avoid this infinite loop. However, it doesn't filter MIDI input like that. It generally just sends whatever MIDI data you give it without applying any logic to it, to provide the most flexibility for your setup.


Quote from: arlo on August 26, 2014, 07:37:42 PM
You should actually be able to send remote control events and follow remote control events from the same device. I haven't tested that in a while, but that's how it was designed to work.

arlo: the remote control through Bluetooth linking must be broken because I have spent the last 20 minutes trying to get my iPhone 5 linked to my iPad 4.  I can get the iPhone to follow the iPad with no issues but as soon as I try to get the iPad to follow the phone, the phone is greyed out in the connection window and says "Bassman's iPhone is not available".  Sometimes doing this even crashed the app, sometimes it can't find any available devices even though they are 2" apart.  I have had a few instances where if the two devices were paired in that direction sometime previously it will auto connect after you cancel and for the rest of your session you will successfully have a 2 way link.  This only happens randomly so it is not exactly reliable.

I don't know what else to try as this feature is very important to us and since it worked before we don't want to live without it.


Quote from: bassman on August 27, 2014, 03:25:56 PM
arlo: Send & follow used to work before version 4.  I do not know how reliably as we just figured the whole remote thing out about a week before we got auto updated to the new version.  Please test it out when you have time as this is a very valuable option to us and I would love to see it fixed in a new release.  Let me know if you need more detailed info.

I just tried this and it worked fine for me. After setting both devices to broadcast remote control events, I first set one device to follow the second, then set the second device to follow the first. Both connections succeeded on the first try. Once connected, I could select a song on either device and the same song would be selected on the other device.

This is with an iPad 3 and an iPhone 5 sitting side by side on my desk. While still connected, I took one downstairs to another part of the house and flipped through a few songs, and when I came back, the other device was showing the correct song.

I know it doesn't help you to be told this, but I do think the problems you're describing are more about flaky network connections than errors in the app code. I'll have to find a new method for connecting devices when I add this functionality to the Android version, so that will be a good time to replace the current Bluetooth framework with something more robust.


QuoteIf the device is not set up to be followed, it wouldn't appear in the menu at all.

This has not been my experience at all. I have 4 devices set to follow and only one to broadcast. The following devices often see other following devices on the selection menu and not just the one set to broadcast. Just as often, they don't see the device set to broadcast in the list.

I'm still having a hell of a time with devices not communicating properly (i.e. devices losing connection)

This has been a problem for us for months now. I'm very interested in the possibility of a "more robust connection method". I REALLY gave the possibility of Bluetooth interference a chance, but our problems still exist in an environment where there are no other Bluetooth devices in operation. The lack of dependable device linking is the only thing keeping my group from being a massive billboard for you. Many of our recent gigs had several thousand in attendance. They all want to know what's on the iPads until they see us fumbling through a lost connection somewhere on the stage


Had the most reliable usage at tonight's practice. Only had 1 following device drop connection in a 3 hour practice and user was able to open device linking, select the broadcasting device again and reconnect for 2 minutes before it disconnected again..


I've started reworking the device linking functionality in Set List Maker and BandHelper, with two goals:

- Improve connection reliability and transmission speed.
- Provide linking between iOS and Android devices.

Unfortunately, the only way I've found to do both requires that all the linked devices be connected to the same wi-fi network. The wi-fi network doesn't need to have an Internet connection, so it could be provided by a cheap ($20) wireless router that you bring to your gigs. It also doesn't need to be provided by a standalone router, so it could be one of your mobile devices with the personal hotspot feature enabled (which usually requires a data and tethering plan on that device), or a laptop with the ad-hoc wi-fi feature enabled (which usually does not require any special service).

My thought is that I could leave the existing, Bluetooth-based device linking functionality in place on iOS, for people who are happy with the existing setup and aren't able to set up a local wi-fi network, but add an option to switch over to the new, wi-fi based functionality. Only the new functionality would be available for Android devices, so anyone using this feature on Android would need a wi-fi network.

What do you think about that?


I think that would work for us very well. We already have most of the devices in a WiFi network on stage because we also use them to remote control our digital mixer. Do you think you could incorporate syncing the metronomes of the devices? That would be really helpful, because this would save a lot of additional cables and network connections for common use cases: E.g. All devices would blink or output the metronome sounds in sync. And would have less need for MIDI over WiFi if every device could output it's own MIDI presets and MIDI time code perfectly in sync.


I think tempo syncing would require a different solution than what I'm working on for device linking. That would require something like a 1 millisecond transmission time versus the 1-2 seconds that I'm targeting for screen sharing and song selections. That's on my wish list, but I haven't looked very far into how that might work.


In the upcoming version 4.1 of Set List Maker, you will be able to switch the device linking functions to use wi-fi instead of Bluetooth. This should be a lot more robust. More info is here:,848.0.html


Would this be available now on the Android version?

Also would an Android device be able to link with an iOS device or vice versa?


This will be available for Android in a few days ... I'm wrapping up the next release now. And yes, you will be able to do device linking between iOS and Android.