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MidiBridge
for iPhone, iPad and iPod Touch
Known Issues
Here are the current known issues/bugs in MidiBridge. Check this list to see if any problems you may be having are already known about. Don't forget about our Understanding MidiBridge guide either.
  • BeatMaker 2.2 users - route events to MidiBridge's own virtual output to be picked up in BeatMaker and not the 'BeatMaker 2' destination. Have flagged this with Intua.
  • BeatMaker 2.2 and SynthStation 25 users - use FreEWI or NoteSplitter module to remap the range of the SS25 keyboard down two octaves to control the drum pads.
  • Animoog (for iPhone) users - there is an issue with Animoog terminating the network midi session when it is started. To workaround, select 'MidiBridge' in Animoog's MIDI input option and then return to MidiBridge and re-make the wifi connection.
  • Music Studio users - currently Music Studio cannot co-exist with some other audio apps running in the background. Audio from these apps is muted when Music Studio runs. The most notable is SampleTank.
  • Music Studio users - Tip: to generate track MIDI events (eg. for MidiBridge to pass to another device via wi-fi), the MIDI Output mode must be set to 'Tracks'.
  • SynthStation 25 and Midi Mobilizer (original) users - please make sure you're running iOS5 or events from these devices will stop when MidiBridge is backgrounded.
  • SynthStation25 and Midi Mobilizer (original) users - there is a bug in MidiBridge when you mix these with CoreMIDI inputs in some cases. Fixed in version 1.4
  • We have found a bug where in some cases with multiple physical interfaces, MidiBridge sends the events to the wrong output. This has been fixed and will be included in the next release. In the meantime there is a workaround: just set an empty filter on each of the input ports that are in use. This will make the events take a slightly different path through the code and route to the correct output. Fixed in version 1.1
  • System exclusive messages larger than 1010 bytes can't be sent over the CoreMIDI network interface. This seems to be a problem with the iOS driver from Apple. Note, this does not affect external interfaces.
  • System exclusive messages larger than 255 bytes can't be received via the CoreMIDI network interface. This seems to be a problem with the iOS driver from Apple. Note, this does not affect external interfaces.
How do I minimise latency and maximise throughput?
Here is a list of things you can try to get the most performance out of MidiBridge:
  • Turn off the Visual Events option in MidiBridge. In slower systems this is important.
  • Terminate as many apps as possible so they are not running in the background taking CPU cycles unnecessarily.
  • Set up a filter on the incoming interface to filter out as much unwanted data as possible. Blocking 'TimeSong' for instance will filter out ticks and active sense messages which may not be needed depending upon what you're doing.
  • Run a little bit of MIDI data through beforehand (maybe to a channel with no sound?) to get iOS to page MidiBridge into memory.

Events stop working after about 5 seconds after I background MidiBridge
If you want events to be processed while MidiBridge is in the background you need to ensure that the 'Run in Background' option on the MidiBridge Preferences pane is switched to 'On'. By default, this setting is 'Off' as running in the background can cause extra battery drain and we want our users to consciously switch on the option and be aware of that. Even when backgrounded, MidiBridge (and MidiVision) will suspend itself after 20 minutes of no events being received to conserve the battery (a local notification is issued by MidiBridge to inform you this has happened). Also, you must be running iOS5 if you are want to use MidiBridge in the background with the original Midi Mobilizer or SynthStation 25.

I want to connect MIDI inputs to an app that supports CoreMIDI network (but not virtual MIDI)
It's a sneaky trick, but you can tell MidiBridge to connect to itself in the Settings pane and the CoreMIDI network interface becomes (very close to in terms of speed/latency) a virtual MIDI input. Step by step:

  • First, make sure CoreMIDI network input on MidiBridge is *not* connected to anything. We don't want infinite loops or duplicate events!
  • On the settings page, enter the word 'localhost' in the hostname and press the 'Connect' button.
  • Back on the interfaces page, connect the inputs you want passed to the other app to CoreMIDI Network out.
  • In the other app, tell it to listen to CoreMIDI Network.

Can I connect two iOS devices together without a router?
Not currently. iOS will not create ad-hoc wi-fi sessions and the personal hotspot feature will only route to the internet and not to the local device. Maybe this will change in the future, but for now, a router/access point is needed to interconnect two iOS devices. You don't need a router/AP if you want to connect an iOS device to a computer, since the computer can create the ad-hoc session and the iOS device can connect to it.

How fast does the app turnaround an event?
During development we attempted to measure the turnaround times of events especially in busy stream situations. We ran a busy MIDI track of 12,827 events over a 4 minute and 51 second period and measured the time taken from receiving the message to having finished dealing with it, all within the app.

Newer devices with faster processors naturally enough process the messages quicker than older devices, but even with an old iPod Touch 2G and original Midi Mobilizer the app was able to pass the events with an average delay of just under 2 milliseconds:

iOS Device MIDI Device Average Process Time
(milliseconds)
iPad 2 Line6 Midi Mobilizer I 0.65 ms
iPad 2 CME U2MIDI 0.13 ms
iPhone 3GS Line6 Midi Mobilizer I 1.42 ms
iPod Touch 2G Line6 Midi Mobilizer I 1.92 ms

If any MidiBridge user would like to see these metrics on their own system, drop us a line and we'll tell you how to get them.



MidiVision
for iPhone, iPad and iPod Touch
Known Issues
Here are the current known issues/bugs in MidiVision. Check this list to see if the problem you are having is already known about.
  • ESI MIDIMATE II - unable to use midi thru with this device due to an incompatibility issue with how this interface works. No workaround - fix in next release. Fixed in version 1.3
  • New bug in V1.2 where settings migration code causes the app to crash. Please delete the app and download again as a workaround. Fixed in version 1.3
  • Channel aftertouch messages can cause problems and stop events from being seen by MidiVision. This issue will soon be fixed in a Line6 firmware update. 4 Feb 2011 - Resolved in MidiVision V1.1
  • Some real-time messages (time clock) are currently not available to apps via Line6's SDK. This issue is also being addressed by Line6 in a pending firmware update. 4 Feb 2011 - Resolved in MidiVision V1.1
How much latency is there with the midi thru feature?
This all depends upon how much data is being presented by the Midi Mobilizer and whether you have a filter setup. For a single event, the latency is unnoticable, but for voluminous data the latency through the system will increase. Essentially it is a trial and error thing, but to ensure minimum latency, don't use filtering and don't rotate/scroll the device.

How much data can be handled?
Again, this depends. MidiVision has a feature where it monitors the data throughput and if it reaches a certain threshold, it will temporarily disable the screen event updates in order to process the data as a priority. You'll see the 'spinning wait indicator' when this happens. Once the data throughput drops, MidiVision will catch up and display the captured data. Of course, the system as a whole (iDevice/iOS/Midi Mobilizer/SDK/App) can only handle a finite amount of data in a given time period. What this actually is will depend upon the speed of the device's chip, other running apps and amount of memory. Your mileage may vary, as they say.



If none of the above helps you with your problem or you have a question, please do contact us via email, apps@audeonic.com or post on our soapbox forum and we will do our best to help you.

 
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Last updated 31 July 2014