I have been spoiled by the ease with which I can connect my iPad up to MIDI applications on my Macbook using the native support for midi-over-the-network provided by the CoreMIDI subsystem in both OS X and iOS.
Is there a compatible Linux implementation? I have found some tantalizing references out there that indicate there may be one, but I haven't been able to find any concrete information.
There is no such thing as a "CoreMIDI network" protocol per se. Apple chose to implement the RTP MIDI standard for MIDI network communication in OS X and iOS, but replaced the somewhat complicated part of the protocol which deals with session discovery and initiation with its own protocol based on Bonjour.
Unfortunately, there is no RTP MIDI implementation for Linux that I know of, which is compatible with Apple's implementation of the protocol. There is a reference implementation by the creators of the standard at UC Berkeley, but it's not a ready-to-use library and it wouldn't interoperate with Apple's version anyway.
There is an implementation for Windows called rtpMIDI, already mentioned in another answer, but it's not free software and so unlikely to be ported to Linux. There is also a Java implementation for Android, called nmj Network MIDI, which is, AFAICS, also only released in binary form under a CC-by-nc-nd license. Both claim to be compatible with devices which use Apple's RTP MIDI implementation.
If you are looking for cross-platform MIDI network communication, I would suggest you look into JACK. Besides audio, JACK also routes MIDI between clients and a JACK server can use another JACK server as a backend over the network instead of an audio/MIDI interface. There are now JACK distributions for Mac OS X and Windows as well and they integrate well with CoreAudio/MIDI resp. ASIO/MMS on these platforms.
Another new contender in the field is CopperLan, which looks very promising, and extends the ability for MIDI network communication (and more) to embedded devices and has lot of other features to offer. It remains to be seen how this will catch on.
RoseGarden could contain something that you might be looking for.
If you can find something within this mostly-notation software, please try it. Otherwise qsynth is, to the extent of my knowledge, a synth but not exactly what you may be looking for.
I'm limited in experience with midi that works. Feedback TOTALLY welcome.
Thanks.
RtMidi should be able to bridge a jack on Linux to CoreMIDI on OSX. rtpMIDI supports Windows and iOS. Between the two you might be able to get something working. If you do, please do post back, I do my audio connectivity via headphone jacks at the moment.
RTP-MIDI support in Linux has been reactivated in February 2013 (I have seen a demo on a Raspberry Pi somewhere on the web made by a guy from KissBox who is also making RTP-MIDI embedded devices) I think there will be a Linux driver quite soon this year, fully compatible with Apple and rtpMIDI implementation. And no problem to use RTP-MIDI in Linux open source world, since it's completely open and free (not like some other protocols which require licensing...)
In order to make host that can talk to RT-MIDI devices (devices cannot initiate a session), you need to have knowledge of the Apple session process. While RTP-MIDI is a open standard, Apple modified it. The specification is not available. This is like most things the fruit company does to take open standards people worked on very hard, create their own -closed - anti innovation- proprietary - implementation by changing a few bytes. For Linux, just give up. Under Windows there is an RTP-MIDI bridge and I found it unstable, sometimes the MIDI port does not show up or it does not connect. Success !!
One alternative to the Kiss-Box is the Cinara MidiGateway that provides USB-MIDI and Ethernet RTP-MIDI interfaces with routing function. You attaches the USB connection to your linux machine just like any USB/MIDI interfaces. Then, data received on the virtual USB MIDI ports are forwarded to the opened RTP-MIDI sessions (and vice-versa) by the box. It is able to manage the Apple RTP-MIDI modified protocol. This solution does not require any kind of specific software running on the Linux host, and it preserves compatibility with other RTP-MIDI devices. Of course, disadvantages is to have to buy something else...
This appears to be a bit tricky. I would like to use existing iPad sequencing apps to control MIDI synths wirelessly w/o having to have a laptop in the mix to do the translation. A Raspberry PI solution would be ideal. The Kiss-Box would do it but it appears to be over 400 Euros. I've already got a Missing Link which is great but it's not COREMIDI, it uses OSC and only works with control surface programs. For now I'm probably going to stick with a wired MIDI, but that sucks...
