AI Chord Analysis and Composition (Autozap!)

Songzap’s AI (artificial intelligence) features are subtle but powerful and are designed to help musicians to work faster, expand their creativity, and learn musical concepts to a deeper level.

The most obvious form of AI built into Songzap is the ‘automated music accompaniment algorithm’ which listens to your recordings and adds one or more instrument compositions that accompany your own work. ‘Automatic music accompaniment algorithm’ is a bit of a mouthful to say and write though, so we generally refer to this simply as ‘Autozap’!

Watch us explore all of Songzap’s AI features!

Music AI is Already Amongst Us!

Now, before we start to explain about Autozap, you’ll probably be aware that there are waves of AI technologies emerging nowadays in music and other walks of life. And these tools bring out fierce debates about whether AI is killing creativity or is a force of evil, or maybe it’s useful and can help in certain circumstances. We’ve been following this evolution closely and have our own philosophies about such things… In general, here at Songzap, we’re not interested at all in AI that looks to replace or marginalise musicians. There are tools coming out that claim to make music from just a simple text entry or other basic input and they are marketed to non-musicians with the tagline ‘make music even if you can’t play an instrument’ or ‘produce a Beatles song in 30 seconds’. This kind of technology is clever, technically, but it really doesn’t interest us here at Songzap, because it in no way helps musicians or moves human creativity forwards. 

BUT, we are ourselves are building AI music tools and we do feel they have a particular place in the world of music making. For instance:

  • Imagine you can play guitar but can’t play piano. Can AI help translate your guitar-specific music knowledge to help you write music for piano? We think yes, and users can only expand their musical understanding by engaging with such concepts.
  • Can AI help with hearing a single-instrument recording of a song in the context of a full band or in different genres? For example, an acoustic guitar recording with hip hop drums and synthesisers. We think yes, because hearing a full band or genre-flipped version can help you reflect and decide if you are taking a song’s creation in your preferred artistic direction.
  • Can AI help someone who is working alone and without access to drums, bass and string or synth instruments, so they are not restricted by their access to instruments or session musicians? We think yes, helping people who have limited access to resources and collaborators is an excellent use of AI!

A final point on the topic before we go into explaining how to use Songza’s AI; it’s worth noting that AI in music is already here and it has the ability to contribute to lower quality music, less royalties for artists and less need to learn an instrument. So in many respects, musicians really need to embrace AI and utilise its capabilities for their own benefit, and stay above a new higher threshold of creativity.. Imagine the power of being a great instrumentalist AND having AI tools at your fingertips. We have seen these kinds of musical revolutions in the past – for example when drum machines, synthesisers, sequencers and samplers first emerged. Many people thought these instruments should be banned (seriously!), but true innovative artists like David Bowie, Peter Hook and Kate Bush embraced the new technologies, and a whole new culture of technology-led music was formed. So here at Songzap, we think AI is just another musical instrument, and we’re excited to see and hear what truly innovative music artists do with it!

Introducing Autozap!

There are three main components to Songzap’s auto-accompaniment feature (Autozap):

  1. An intelligent chord recogniser that listens to your recordings and maps out the chord structure of your songs and song sections.
  2. An intelligent music composition engine that looks at the song’s chord chart and performance dynamics and writes drums, bass and pad music scores to accompany your recordings.
  3. A suite of expertly produced sample libraries that allow you to find the right feel, vibe and genre for the auto-accompaniment compositions.

Most of the action relating to Autozap is managed through the Songzap AI menu. To open the menu just press the Autozap button in either of the Grove or Arrange pages and you’ll see the Autozap options menu appear, as shown in Figure 1.

Figure 1. Songzap’s AI (Autozap) menu is launched from the Groove or Arrange pages.

From the Autozap menu, seen in Figure 1, you can decide if you want to enable all of the AI features when the process runs. Most likely you will, so these are all switched on by default. 

At the top you’ll see the Chord Analysis option. Chord Analysis listens to your recordings and produces a chord chart of the song, which the AI accompaniment then uses for composition. You’ll most likely want this switched on, unless you’ve manually input your chord chart with the chord editor (which is described in more detail below). Now, when you enable Chord Analysis, you also need to tell Autozap which recording channel (or track) you want it to analyse. Because Autozap is aiming to work out the chords of the song and song sections, it;’s best to choose the track of recording which has the most chord-like performances. So if you have recorded guitar chords onto Loop Track 1 for each song section (see the Loop Recording tutorial for more info on this!), then select Loop Track 1. If you haven’t used Loop Recording and instead used linear Tracking to record (see the Tracking tutorial for info on this!) then you might need to select the Linear Track which you recorded your chords onto. Note that running the Chord Analyser will override any chord charts that you already have created.

In the centre of the Autozap menu, you have the choice of creating music accompaniments for the Beat, Bass and Pad Groove instruments. Thai is where the AI within Songzap looks at the chord data and the dynamics of your recordings and comes up with music that should accompany it well. Of course, this is just a starting point really; after Autozap completes, you can explore the Beat Bass and Pad compositions in the Groove section (as in Figure 2) and decide if you want to make any tweaks or modifications. Feel free to tap and edit the drum beat, simplify or enhance the bass pattern, and shift the pad sound up or down an octave. All the Beat Bass and Pad controls are described in their respective Groove tutorials, so take a look at those to get full control of the AI-assisted compositions).

Figure 2. Beat, Bass and Pad compositions generated by Autozap.

Perhaps the most impact you can have is simply by setting the sample pack for each of the Groove engines. The drums can be anything from rock, electro, hip-hop to hand percussion; bass can be electric bass guitar, acoustic double bass or deep synth bass; and the pads can be organ, choir, synth, strings or piano. So just bey changing the playback sounds after running Autozap, you can considerably change the feel and genre of your song.

Working with Sections and Song Structures

Autozap works best when you start to develop a formal structure for your songs. This means deciding how many sections there are in your song, deciding what type each section is and deciding how long each section is. This is because Autozap likes to generate a song that takes the listener through a sonic journey that may have heavy and light dynamics in places, simple and complex sections, and passages of intensity alongside sections of calm. In general Autozap will generate bolder, more impactful Chorus sections and slightly more sparse Verse sections – which is what many top music producers and mix engineers aim to do when crafting a song for release. But of course, there are no ‘rules’ in music production, so you can always change things around and do something different after Autozap completes if you want to.

When running Autozap, you have the option to just run the AI for the currently selected song section, or for the whole song (see the bottom half of the Autozap menu in Figure 1). It depends how you are working on a song as to which you choose. Sometimes it’s a good idea to record loops for each song section (verse, bridge, chorus, instrumental ect) and then run Autozap for the whole song. On other occasions you might have altered the performance of one particular section and you want to run Autozap again just for that section of the song.

The Chord Chart

Chord charts are commonly used by session musicians and musical collaborators to communicate with each other about how the song is performed, in a quick and concise manner. So we’ve designed Songzap to use chord charts in a very similar way – as if you have a session musician who you need to explain the song chords to. Autozap can also be really useful for showing you your own chord chart, since many musicians don’t always know exactly what chords they are playing at a moment in time. So Songzap can hopefully help you refine and improve your musical knowledge through this process too.

To open the Chord Chart, press the chord chart button on the Groove or Arrange Page (see Figure 3).

Figure 3. Chord Chart Button and Chord Chart.

Songzap’s chord chart displays a row for each bar in the selected song segment, and the beats and intervals for each bar along the row. If you are using 4/4 time signature, there will be 4 beats with 4 intervals per beat, giving a total of 16 intervals per bar. Similarly, working in 3/4 shows the same but with only 3 beats of 4 intervals (12 total). Equally, 12/8 time signature is divided into 4 beats of 3 intervals which results in 12 intervals per bar also. When playing the song you’ll see the blue playback indicator scrolling through the chord chart, which helps with understanding sonically where each chord change occurs.

A chord label can be placed on any interval of any bar. Most commonly we see chord changes on the first beat of a bar (as is shown in Figure 3), but it’s not uncommon to change chords on any beat – and sometimes we have purposefully ‘pushed’ or ‘late’ chords which occur on 16th or 8th intervals between the beats too. Autozap will do its best to put the right chord labels in the correct positions, but you can always modify or add your own too if you want to go manual on this. 

On the top right of the chord chart there are + and – buttons, allowing you to add or remove rows (bars) from the chord chart. If you have a chord progression that repeats after 4 bars, then it makes sense to only have a 4-bar chart. Occasionally you might have a more complex chord progression that is 8 or even 16 bars, in which case you can expand the number of rows to accommodate.

Modifying Chords

It’s possible to modify the chords that Autozap provides and manually create your own chord chart from scratch if you prefer to. Tapping on any interval in the chord chart will launch the Chord Select menu. As shown in Figure 4a, you can use the Chord Select menu to define and place any chord with any musical root and the following modes: major, minor, power (5 chord), sus2, sus4, diminished and augmented. From the menu, you can also move the chord selector position left and right through the bars and intervals with the single arrow buttons. The double arrow buttons appear when a chord is selected, and these allow you to shift the selected chord left and right through the musical timeline too.

Figure 4. a) the Chord Select menu, b) with flat notation selected, c) with chord extension and bass note option menus displayed.

You’ll notice the sharp and flats button in the middle at the bottom of the menu, allowing you to choose the notation that you prefer. As an example Figures 4a and 4b show the selection of sharps and flats notation respectively.

It’s possible to play many complex and wonderful chords on instruments like the guitar and piano, so it’s also possible to select a number of chord extensions and a bass note option too for the Chord Select menu (as shown in Figure 4b). The chord extensions supported are 6 chords, 7 chords and major 7 chords. The bass note selector is useful when using slash chords, or if you want to force the Bass engine to play a particular note at a specific moment. For example, on guitar it’s not uncommon to play slash chords that have an alternate bass note played with the thumb holding a fret position on the low E string. A good example is the F#/Asus2 chord commonly used by Radiohead in songs like Fake Plastic Trees and Karma Police. In reality this is a simple Asus2 chord played on the guitar, but with the thumb held on fret 2 of the low E string, giving a F# bass note.

It’s fair to say that Autozap’s chord recogniser might not always be able to work out exactly which weird or wonderful chord you are playing, since there are thousands of permutations and in many occasions it can be subjectively argued to be one chord or another; but it will always identify a suitable chord that is in key and harmony with what you are playing, and you are enabled to tweak or modify this to something different if you prefer.

Musical Key

Finally, on the chord chart, you’ll notice that there is a musical key defined for each segment of the song. Some songs maintain one key consistently throughout the whole song, whereas others change key once or more during different song sections. Autozap identifies the key for each song segment, and this helps the playback engine to play interesting bass patterns and pad accompaniments that go beyond the triad of notes of a single chord. Knowing the key of each segment, along with the chord chart, allows Songzap’s AI accompaniment to play much more like a human musician than if it just knew the chords or the key alone. Of course, the key of each section can be modified or set manually too. Just tap on the Key label in the top left of the song chart and the Key Select menu will appear (as shown in Figure 5.)

Figure 5. Key Select Menu.

In the Key Select menu, you can select or modify the musical key for the selected song section, including relative minor keys and sharp/flat options too. If you want no key to be selected, press the centre of the chart and Songzap will work happily with no musical key defined.

You might notice that Bass and Pad interfaces (shown in Figure 2) also display the section key and current chord as the song plays, in the notation menu above the keyboard display. This also indicates if the chord being played is ‘in-key’ by giving the ‘chord type’ in standard Roman numerals if it is. This relates to a little background harmonic theory which is quite simple to explain and is worth all musicians having a basic understanding of. We’ll explain this very briefly below, but it’s worth looking at some musical training websites or books also to get a full understanding…

Within the realm of (the commonly used) diatonic harmony, we can construct a chord for each of the seven notes of a major scale, making sure that the notes of the chords we construct stay in key with the scale chosen (the key of the song or section). To do this, we follow a simple formula for each degree (note) of the scale. For the first degree of the scale, we construct a major chord; for the second and third, a minor chord; for the fourth and fifth a major chord; for the sixth, a minor chord; and for the seventh, a diminished chord. This ensures that the chord triads we have constructed only use notes from the key/scale selected (and this also applies to chord extensions). For example, if the key of the song is C major, we can quite happily use the chords C, Dm, Em, F, G, Am and Bdim, and we’ll be in agreement with diatonic harmony rules (which applies to millions of songs). It’s also worth noticing the intervallic construction (the semitone and full tone steps in between each note) of the scale itself. In the key of C, for example, it would be:

As this intervallic pattern applies to all major scales, we can think of and represent the respective chords also in terms of intervals (which enables easy transposition of songs to any key). And this is why you will often see chord charts that utilise Roman numerals, with uppercase numerals indicating major chords, and lowercase numerals indicating minor chords; the seventh chord (diminished) has an additional indicator to show that it is subtly different from the other minor in-key chords (it contains a lowered – diminished – fifth in the triad):

Wrapping Up

Learning and understanding a small amount of music theory, such as that above, can really help with songwriting – allowing you to more quickly identify what chords in a progression will work well in a song you are writing. It can also be incredibly powerful when adding harmonic layers, basslines, solos and arpeggiated patterns to a song you have already written and recorded.

So hopefully you’ll agree that Songzap’s AI engine is there to help musicians work faster and more expansively, but also to develop their musical knowledge and understanding too. The best way to learn is through doing, which means writing, listening and reflecting in the world of music. Autozap helps by providing information and examples to the musician, who can then start to learn why such suggestions were made and use their unique (human!) intuition to take things to the next level.

So go ahead, embrace AI and let’s see what the exciting future of music sounds like!

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