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.
Sonuus G2M demo...control synths with guitar
Control your synths with your guitar! 
Comments
@Flo26 very cool...love the different nuances you can get from that!
Beautiful both performance @Derek and @Flo26!!
@Derek in the video I can see a lot of latency, how you can play in this way on a base?
For this purpose what is the best, Midimorphosis, Midi guitar or G2M app?
Thank you
Francesco
Very nice sounds and performance guys.
@pexfra midi guitar is both poly and monophonic...G2M is mono. As far as the latency goes...I record the tracks live into Auria ( or whatever I'm using at the moment) and then have to line the audio up with the video in editing....sometimes I'm close enough to not really matter...but at times it doesn't match up perfect. I think YouTube has some effect on that as well sometimes. G2M tracks the best and has the least amount of wrong notes. Midi guitar is ok if you play really slow.
Obviously, I'm not going to be the most impartial guy on this… In my experience, MIDI Guitar tracks a little bit faster than MIDImorphosis, but I find that it gets more wrong notes -- it'll really commit to a pitch, and stay there, even if it's not right. With my app, you may hear a note pop out briefly, and then it'll switch to a different note -- that's the app trying to figure out quickly what the incoming pitch is, and then finding out that it's wrong. G2M also commits, and with my guitars, it grabs a lot of wrong notes when I play quickly, particularly at the lower registers. I like my app the best (surprise, surprise!), but I can see the merits of the others -- I've got a lot of respect for both MIDI Guitar and G2M, and depending on how you play, they might be the "right choice." MIDI Guitar is free to try -- people should absolutely get that, and put it through it's paces, to see if it's what they need.
My app also supports off-line conversion -- so you can play guitar live, and then convert to MIDI, to minimize latency issues. The off-line conversion should work on older hardware, so an underpowered iDevice is still useful. There's support for AudioShare, recording and playback over Audiobus, and playback of converted MIDI.
As @Flo26 says -- none are perfect; considering the constraints (audio pipeline delays, limited processing power, all strings mixed together in one input), it's impressive that they work as well as they do. Depending on how you play -- you can get good results from all of them, or you can make them crash and burn. Playing style (and being able to adjust how you play) are critical. Mute notes if you don't need them, pick cleanly, avoid slides, bends, vibrato (for polyphonic modes), minimize fret noise.
The best system I've played is the Fishman TriplePlay. I was so impressed, I bought one. Fantastic hardware solution, crazy fast tracking, but $400. For 10% of that, you could pick up all three apps, and have money left over. The apps are not as fast as the Fishman, but if you play carefully, you can get a lot of good use out of them.
@SecretBaseDesign I've notice some poor tracking in lower registers as well...maybe too much string resonance? Anyhow...hit me up when you get a chance. Going to give your app a whirl again this afternoon!
The poor tracking on the lower registers is due to the frequency of the sound wave, versus the size of the FFT window. Lower frequency notes have fewer cycles within a 256/512 sample window, and if the FFT window is too small, the low frequencies are just not detectable. (Headphone jack interfaces, by the way, are a killer here -- they filter out low frequency stuff, so even with large FFT windows, the low notes are gone).
A low E on a bass is about 41hz -- or 41 full sine wave cycles per second. If you're sampling at 44.1khz, that's about 1076 samples before you have a single cycle, which is also about 24ms -- a latency that is noticeable. Any app that responds faster than that is making a guess (maybe grabbing a harmonic), because there's no way to really know what the pitch is until you've got a full cycle (or two or three). Higher pitch notes are easier, because you get more cycles within a single FFT window.
I play bass as well as guitar -- and I want to be able to use the app with bass, so I've gone with the larger windows. My app doesn't track as fast as G2M, but from my experience, it gets the lower notes right more often. There's actually some additional software trickery that I'm doing (and I'm guessing that MIDI Guitar does as well) to compensate for this; a little bit of special sauce in the coding.
The settings you had on MIDImorphosis looked fairly reasonable -- the trick is to figure out the sweet spot for playing (speed, intonation, etc.), and try to stay in the zone. The apps each have their quirks, but if you play within the limits, they all can work.
@SecretBaseDesign just want to say thanks for your explanations. I occasionally see you go into detail here and on Discchord comments and I really enjoy reading them.
@SecretBaseDesign , @DerekBuddemeyer, @Flo26
thank's a lot for sharing your experience here, this is very intersting topic, I'm gonna test all 3 apps , I'm very curious!!
Francesco
Here's a short instrumental created using an aluminum beer bottle blown across the top with MIDImorphosis triggering SquareSynth filtered through fx of Swoopster and AUFX:Dub in AB.
@Paulinko -- wow, high tech jug band music! (And it made me wonder if there was a washboard app. And sure enough, iWashboard, sitting there in the app store. There really is an app for everything).
@Syrupcore -- glad the explanations are useful. My day job is being a computer science professor (for reals), so I fall into lecture mode pretty easily.
@SecretBaseDesign hah! Rad. I'd go to your classes and yell at compilers any day.
@SecretBaseDesign found this video....it's from a while back...but this was so much fun to use Midi Guitar
I've used g2m and ThumbJam for mono tracking. I found ThumbJam better. I'm planning to test Jam Synth but didn't yet.
Midi Guitar 2 is the absolute gold standard in this category. I've tried the others, and MG2 is magical. I never play a guitar part these days that isn't buttressed by a synth or an organ or a sample or whatnot. Finally got the sound I've always heard in my head dialed in!
Hey, I enjoyed that!
Thanks for sharing.
Also, I'm another Midimorphosis fan; I find it to be both responsive and versatile.