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App to live transpose midi loops based on chords played?
Hi,
Can anyone suggest an app and help me end my search?
Goal
I would like to set the key of my performance then use a midi keyboard to live record a bass line on a looping pattern and then play chords and get the bass line to 'follow' the chord progressions?
So far I have found:
- Hardware: Roland JD-XI has an interactive chord feature shown in this youtube video here
- Hardware: Yamaha QY-100 has Chord follow
- Hardware: the rather lovely Oxi One has harmoniser mode
- Desktop plugin: Chordprism has chord/key shifters
As for apps,
Prism looks like the perfect looper, but I can't tell if it can live transpose.
Drambo and Eg.Nodes seem promising but I can't find anything definitive.
Mozaic Plugin Workshop and Mela seem so open ended that they might be a solution.
I'm obviously hoping Loopy Pro will have this feature, when the midi looping comes out.
I've been on this search for weeks and while it's been enormous fun, I would like to make some music now!
I'd really appreciate any help you can offer.
Cheers
Daniel
Comments
So, you need a transpose MIDI effect?
Will this one work?
https://apps.apple.com/ca/app/midiflow-transposer-audiobus/id1175575102
That's not planned at this time. You may want to search the Loopy Pro Roadmap site to see if there's a similar feature request to upvote and comment on, or to add a feature request.
You can do it in dRambo however it does require a bit of setting up.
For the most part, just transposing a bass part and keeping it in key should work. Rozeta Scaler is particularly good for that. But you need something to detect which scale degree the chord is in.
The trick is recognizing which note is the root note of the chord. As long as the bass note is always the lowest note, that's not a problem for even a simple mozaic script, and I'm sure there must be one already available. But if you play inversions it's harder. In that case it's far easier to deal with if you can somehow trigger the bass note on a different midi channel.
It's not as easy as you might think to determine chords and react to them in realtime.
Figuring out the key of a song from the chords in real-time and transposing other clips accordingly is non-trivial. This seems like something for a specialized accompanist app/plugin.
Does Scaler do this sort of real-time analysis?
I agree working out the key from a chord is non trivial!! I'm expecting to set the key in advance (or scale and root note) - from what I can tell you have to do that on the JD-XI and QY-100.
I've been playing around with a jsfx script in reaper and am starting to appreciate the nuance in the request. I don't know whether there is a 'standard' solution, I'd guess not. Like wim says, the root note of the chord can be used, but there are other paths...
Thanks for the comments, I'll have a look at Rozetta Scaler and midiflow transposer and report back.
Could you build the bass line as a pattern of offsets in something like StepPolyArp, and drive it with input chords? I do something like that a lot using ChordJam.
I would use Drambo because at some point, you'll hit a few cases where transposition matching a chosen scale will not always end on the notes you want. In Drambo you can add fine offsets or even make 1:1 transpositions for each note separately.
I'd like to record the bassline live, would that be possible in StepPolyArp?
@wim - You hide you light under a bushell!!!
I got a proof of concept working in Mozaic using MIDI Note Shifter followed by Simple Scaler
Then I realised both of them were written by @wim - Nice one!!
I'm tidying up a modified version of the note shifter that avoids hanging notes when the transpose amount or output channel is changed mid note.
Thanks for sharing :-)
So you want to build your own auto-accompaniment ! I remember having fun playing chord changes and transposing on an old Casio I had.
I could see a use for the Breakbeat genre ala Kaidi Tatham (although I seriously doubt he's using it lol)
Exactly Etienne!! But with the ability to live create the backing loops!
I love Loopers like loopy pro, but I never know how to handle the chorus and bridge - This has potential.
You should have a look at iBassist Live Midi In. I think you may be able to work something out with it.
iBassist Live looks amazing! But I'm trying to generate ALL the backing loops live, nothing autogenerated or prerecorded.
My Smart Chord BassMozaic script determines and outputs the bass note of chords and their inversions. But processing might take some msec and if used to tranpose another parallel running midi source, that might miss correctly transposing the first note that came in at the same time as the chord.
You‘ll find a similar problem with live input of chords to iBassist - the first note might be using the transpose of the previous chord.
Host don‘t offer control about the order of midi plugin processing - but to work correctly, things like chord detetction needs to run and finish first, then its output configures the scale transposition and after that the notes to be transposed should arrive at the plugin doing the transpose. So the live-sequencer producing the bass melody needs to run at the end of the midi processing chain. Since everything happns in a single midi processing round before producing one audio buffer, this doesn‘t mean that chord and notes are not ‚straight on point‘ - the midi cmd buffer supplied has the option to accuratly specify the point in time (in the future) when the note will occure - so they are always computed a bit earlier.
Btw, at 44.1khz and 256 sample buffer that‘s 172 runs through all midi plugins and all audio buffer transfers for all instruments and plugins per second… It‘s not the midi processing itself that is the problem, but the inability to specify the order of processing and when midi is transmitted between the plugins ;-)
Prism has an “ECHO” feature that allows a track to “echo” notes / chords from another track’s sequence .. there are also options for step/octave up/down, mono/poly, gate and harmonize to help you further fine tune your accompaniment ..
Thing is, it doesn’t transpose live, i.e. it wont live transpose chords/notes/trigs straight out of the keyboard that are not part of a sequence already; the echoing track echoes chords/notes from a track’s sequence that you point it to. Prism’s developer @A_Mortal_Mage might have more to say about this ..
Here’s a screenshot of the ECHO description from the app ..
Okay, back to this post...
Would an AUv3 Pitch shifter effect do the job? Live transposing and pitch shifter are very similar for the output you want.
Sure, one stretches audio, but if the algorithm used to write it is decent, that should be a trivial issue.
Nice work on the Smart Chord BassMozaic script @_ki
Thanks for pointing out the timing issues that trying to transpose notes based on incoming notes will have.
Thanks for the suggestion @seonnthaproducer but I don't think a pitch shifter will work here - The goal is to transpose in key, so if the key is C Major a C major arpeggio would transpose to an A minor arpeggio. I think with pitch shift it would always stay major.
Thanks @mikejohn, I love the direction that Prism is going in and have contacted @A_Mortal_Mage to see if live transposition is possible now or in the future.
Umm…I could be wrong but isn’t C Major and A minor in the same scale? It’s the same thing as starting a song with the 6th note of C (and calling it Aminor) and the first note of C (and calling it C major).
Then again, I’m not really an educator. I just use the tools I have to solve problems that come my way. If I had that problem, I’d either transpose the MIDI or use a pitch shifter on the audio.
Then again, here’s what my AI assistant (taught with everything I know from iOS, the ChatGPT framework, and the Audiobus community) mentioned:
For your setup, it sounds like you’re looking for an iOS app that can:
Here are some potential solutions on iOS that may align with what you’re looking for:
Loopy Pro (with MIDI updates)
• Why: Loopy Pro is indeed a powerful tool for live looping, and its upcoming MIDI support might include advanced functionality to handle chord/key-based transposition and follow along with harmonic changes.
• Tip: Keep an eye out for Loopy Pro’s future updates. Meanwhile, it might already handle your basic looping needs if you’re okay with setting the key manually each time.
Drambo
• Why: Drambo is a modular audio environment on iOS that has MIDI features and a lot of flexibility. Some users have been able to create setups with Drambo that involve MIDI-following harmonies and transpositions, although it may take some setup work.
• How: You could experiment with using Drambo’s MIDI utilities to set up a patch that tracks the chords and shifts the bass line. Drambo has a supportive user community, so you may be able to find a preset or patch that fits your needs.
Mozaic Plugin Workshop
• Why: Mozaic Plugin Workshop is powerful for building MIDI manipulation tools within iOS and might be able to let you script a setup where your bass line follows chord progressions.
• How: You’d likely need to create or download a MIDI-following script to get the bass to follow the key and chord progression in real time. If coding isn’t your thing, there are user communities and script libraries that may already have something close to what you need.
AUM + Various MIDI FX Apps
• Why: Combining AUM (for routing) with a MIDI effects app like Scaler (when available on iOS), ChordBud, or Rozeta Scaler might give you a modular setup for setting keys and having MIDI-following bass patterns.
• How: Use AUM as the main host app, and route your MIDI keyboard through MIDI FX to create the effect of a bass line following chord changes. Scaler-like apps can recognize the chords you’re playing and send appropriate notes to the bass track.
Mela 3
• Why: Mela 3 offers customizable MIDI effects, which might give you a way to experiment with harmonies and real-time transposition.
• How: Explore the MIDI FX section and check if it has real-time transposition options. If it doesn’t handle your needs out-of-the-box, you may be able to route it within AUM for additional flexibility.
Community-Driven Solutions
You may also find user-created setups on forums like Audiobus or iOS Musician groups. Many users share templates and patches for apps like Drambo and AUM, so asking there could save you some setup time.
Since it sounds like you’re exploring each app’s limitations and capabilities, Drambo and AUM combined with a MIDI FX app (like Rozeta or ChordBud) may be the closest options on iOS for getting a bass line to follow your chord changes. Each solution will have a learning curve, but with AUM’s routing and Drambo’s modularity, you should have a good starting point to create your ideal setup.
If Loopy Pro eventually adds this functionality, it could be the perfect solution for you. Meanwhile, trying a Drambo + AUM configuration might be the quickest route to music-making.
@seonnthaproducer
It simply won't work.
Let's say the bass line is C D E when the chord is C major.
If you pitch shift the bass line to -3 while playing a A minor chord, the bass line will be A B C#, so still major as @Errorplane mentioned.
p.s. : I'm saying this amicably, but nobody wants to read AI answers, keep it real dude
You're right about the shift, but hear me out...
A song written in A Minor is the same as a song written in C major because Aminor is the relative minor of CMajor.
So, transposition will be the same thing as if you transposed in Cmajor.
Oh, in regards to AI in general, I'll be honest...it really doesn't matter. If I have my assistant write this out from the perspective of SEONNTHAPRODUCER, I still have to stand by everything I've said.
I'm actually not a real person in this forum. This account is a digital representation of who I am as a person. An avatar of some sorts.
If I said "every single post I've ever made has been written by technology...", there would be an outrage.
Except..it's always been that way. I’m currently using voice to text via Google Keyboard to write this response. I am not actually typing this.
Because it is so easy for people to misunderstand everything I say. But when we are in the real world, and we're talking face-to-face, that's my real personality.
But in regards to the my prompted post, I did that on purpose. Trying to test a particular sequence of words to try and trigger an AI response. The account was made new and we've had a wave of bots coming on the forum.
I would be interested in something like this as well. What comes close to what you're asking for is one of the many synths with a built-in arpeggiator that follows the chords (or midi input) you play - in this case the midi loop is built into the synth arp. Some of the arps can get complex depending on the synth you use.
off topic to this post, but we are having to face some uncomfortable questions in this area.
Great, that makes 2 of us
Can you give any examples? The Korg Karma is the most interesting I've come across.
I'm Focusing on loops generated during the performance, nothing prepared. But if that fails due to lack of skill, you can be sure I'll be welcoming the robots into the band faster than the speed of electricity!!
I think MidiStep will do what you’re looking for. If you jump to about 21:50 in this intro video, you’ll see chords being transposed to a sequence.
https://apps.apple.com/us/app/midistep/id6680182647
I was thinking of Bleass Arpeggiator, but what GRiker said. I use some hardware synths that can do that (Arturia Minifreak, Novation, etc.).
I owned a Korg Karma back in the day, and I can tell you that MidiStep can do a lot of what Korg Karma did and more. Check out the developer’s MidiStep YT MasterClass videos and EdZab’s Companion Docs thread.
You haven't said anything incorrect there, but you've misunderstood the context. With pitch shifting you're not transposing in scale. A C major chord and an A minor chord do have the same notes. However, it's the intervals that make a minor vs major cord.
A major triad's intervals are 0 +4 +3 semitones between the notes. A minor triad's intervals are 0 +3 +4 semitones between the notes. If you just take a C major chord and pitch shift it down to A, you still have the same major semitones difference between them. You will have an A major chord. You can trust me on that.
I don't have time to explain in further depth right now. If you're interested in not continuing to be wrong on this point, you really should look further into what you're saying.