Audiobus: Use your music apps together.
What is Audiobus? — Audiobus is an award-winning music app for iPhone and iPad which lets you use your other music apps together. Chain effects on your favourite synth, run the output of apps or Audio Units into an app like GarageBand or Loopy, or select a different audio interface output for each app. Route MIDI between apps — drive a synth from a MIDI sequencer, or add an arpeggiator to your MIDI keyboard — or sync with your external MIDI gear. And control your entire setup from a MIDI controller.
Download on the App StoreAudiobus is the app that makes the rest of your setup better.
Midiguitar app
This is not directly Audiobus related but I have noticed that there are several guitarplayers lurking around her and this app can be useful to trigger iOS instrument apps with the guitar, and record them using audiobus ;-) Hope this is ok.
Anyway, I have kept an eye on the Midiguitar App and until now it has been kind of useless. The app transforms audio input to midi and supports polyphony, chords. The app was updated today and to my suprice, it triggers fast and much better than before. It supports virtual/wifi/cable midi. I have not tested virtual midi yet but the included internal piano worked very well and if virtual midi works as good this app will be very useful. I will do more comprehensive testing later and come back with my impressions but this looks really promising. If anyone else has tested the latest version please share your experience. I'm really exited :-)
Sorry AB team for this little OT post. Who knows, maybe the dev will include more internal sounds and include Audiobus in the future 
Comments
I saw the update this morning and was pretty excited to try it out, but with my wife asleep and being late for work already, I had to slip back into reality. I also have the Sonuus G2M and Shredder apps, but triggering is a bit hit or miss with those. G2M is better than Shredder in my experience, but Shredder has a built in synth and recorder, so it is interesting in that regard, although virtual midi makes that irrelevant.
I noticed this update too, looking forward to trying it.
Just to chime in, ThumbJam has this feature too, albeit more hidden away.... the button with the mic-and-notes (on the bottom of the iPad sidebar, or in the aux sidebar on iphone/ipod, which you get by pressing the button with three little icons on it). All the above apps and TJ have slightly different strengths and capabilities, so try them all.
TJ's is monophonic, but lets you lock to the selected scale, chromatic, or free, octave offset, plus gives you some glide controls when driving the built-in sounds. Virtual midi, of course. Can be fun with tracking any sound source.
Seriously: Is there anything Thumbjam doesn't do??
Are there any good TJ tutorials (text or video) out there? I struggle greatly figuring it out. As powerful as it is, every time I open it up I have no idea where to find what I want to do.
@sonosaurus - thanks for that. I recall hearing that some time back, but didn't get around to trying it and then lost sight of it. I think all the other apps are monophonic as well. It would be interesting to hear whether there are any that are poly. Playtime tonight!
@jesse_ohio, there aren't many official tutorials but hopefully that will change. Please go to the forums on thumbjam.com and ask some questions there about the things you want to do (but struggle finding), and I'll address them specifically there!
@funjunkie27 MidiGuitar (this topic's subject) does support polyphony, but it's probably not quite responsive enough to be useful yet (I haven't tried the latest version of it). It is definitely a challenging problem.
@sonosaurus - I gotta check that out...I think I was always playing it in a mono manner, thinking it wasn't poly.
I've played with TJs "Audio to midi" function and it is kind of hit or miss. Don't get me wrong, it is a nice feature but it is hard to get a tight performance with it. Can't wait until the kids are in bed so that I can test Midiguitar properly. High hopes.
@jtrake, I totally agree, TJ's can be a little fidgety. It does best when driven by a voice, where attack transients and other string vibrations don't interfere.
Just tested Midiguitar (with a guitar as input) and I can't tell much difference from the previous version. It is still limited to chromatic with no pitch bends, no octave transpose, and the virtual midi is of the "broadcast to everyone" style. But it definitely doesn't have the false triggering problem that TJ tends to have, and the polyphonic implementation is kind of neat, appears to be limited to about 3 notes, but 2 is more consistent.
Just had a play about with my guitar into Thumbjam and it tracks really well (in mono)! Then I added Midi Guitar app, playing through Thumbjam but with polyphony, and recorded a couple of tracks into MTD via Audiobus. Have a listen:
Well, Now after some more testing of the app my conclusion is, close but no cigar. The latest version is an improvment but... Polyphony works but it still misses notes here and there little to often, even if played clean. The lack of pitchbend support is a big one. Pitchbend is essential to get a natural feel. Midi implementation is hmm simple and the app behaved little strange in the background for me etc etc. After testing I started Thumbjam and actually enjoyed playing with that more than Midiguitar, single note lines of course. Probably because it supports pitchbend.
I hope they keep on improving the product and finally nails it and I will for sure keep an eye on this one.
Here's a quick demo I made using MIDI Guitar - using MIDIBridge's key split to play two of Thumbjam's instruments simultaneously, recorded through AB into Multitrack. http://snd.sc/YWh1Ls
It's certainly not perfect, and as with all MIDI to guitar systems you need to play very cleanly to get consistent results, but the fact that I can do this with only my phone and a guitar is amazing.
I tried the updated app this morning as well and it doesn't do the polyphony very well at all unless strumming extremely slow. But yeah the pitchbend is a dealbreaker. I need to try the thumbjam version for sure. Love thumbjam!
Note that in TJ you have to set the snap control to the smooth diagonal line in the popup pitch tracking controls (no snap) in order for the pitch bend to work. It would be cool if I supported it in the snap modes too, where an initial trigger will snap but then any variation during the note will bend relative to the initial one. I'm putting that on the list.
I've not tried the app since the update but I have the You Rock Guitar and it seemed to track allot faster than the app did. Anyone else try a YRG yet?
I have it. After a few tweaks it tracks really well.
@mgmg4871 I hate to tell you this but I've got my eye on a new toy due out later this year.
http://jamstik.com/
@thesvh, is that you Scott? From the YRG site? Either way, good to have you here.
@AkaMarko, so cruel. Lol . Looks awesome. How much will I be spending?
Yeah Jamstik is going to be awesome for guitarists. I can't wait. After that I can't afford it. Word on the street is they also have a full 24 fret one coming. ;-)
Cool!
@thesvh Yes I had a play with a YRG that one of my friends had but I didn't find it very natural - it didn't feel like a real guitar because the strings you fret are fixed so you can't bend them and I found I was unnecessarily applying too much pressure.
Good tracking though!
@Ryan, the company hints at a price tag f $249-$299.
I'd probably part with $250 for it f it's a good tracker but no more. I aready have the You Rock Guitar Generation 1 which I paid around $215.