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SmokeyVW
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Registered: 06/13/06
Posts: 7145
Location: N/A
 
Cross-Fade Percussion Tracks
Monday, September 10 2018 @ 06:20 PM CDT

seeking advice on percussion tracks

the scenario: i'm using some home-grown software for generating partly random, partly algorithmic percussion tracks. some of them actually sound fairly interesting: if you repeat a loop several times, a "main beat" emerges in your mind. in a lot of ways i think it's a musical perception thing. i have yet to find a method of algorithmically finding that beat, but hey, it's a work in progress.

now for the real question. i have the software generate several of these looping tracks, and i want to gradually cross-fade from one to the next. even if i manually adjust for where the "main beat" is, a purely audio-based cross-fade sounds pretty bad mostly.

i've also tried to cross-fade by selecting the loudest note of each instrument as the gain of one track goes down, while the next goes up. but that comes out a jumble.

any suggestions on how to cross-fade rhythm tracks? i know i've done it manually in GarageBand in the past, but it was usually from one loop to another very similar loop. in this situation, the loops can be VERY different. i'm at a loss at the moment.

thanks in advance!
chikoppi
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Registered: 04/02/04
Posts: 2012
Location: N/A
 
Re:Cross-Fade Percussion Tracks
Monday, September 10 2018 @ 07:16 PM CDT

I'm not exactly sure what you're trying to accomplish, but you might try "recede/emerge" rather than cross fade.

When the source of percussion becomes more distant not all frequencies drop off at the same rate (which is what happens when you fade the volume). Instead, the high and low frequencies recede at a faster pace than the low-mids,

Think of a bass drum smacked right next to you vs. heard from across a large field. It goes from being perceived as a crack to more of a dull thud. By having the low-mids appear first (and recede last) you might get a different interplay between patterns than you would from a straight-up volume curve.

You could automate a high pass and low pass filter to gradually modulate the frequency as tracks fade in and out. A little automation of a reverb with reflections would heighten the effect.

“Ya, that idea is dildos.” Skwisgaar Skwigelf
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SmokeyVW
Forum Full Member


Registered: 06/13/06
Posts: 7145
Location: N/A
 
Re:Cross-Fade Percussion Tracks
Monday, September 10 2018 @ 07:29 PM CDT

Quote by: chikoppi
I'm not exactly sure what you're trying to accomplish, but you might try "recede/emerge" rather than cross fade.

When the source of percussion becomes more distant not all frequencies drop off at the same rate (which is what happens when you fade the volume). Instead, the high and low frequencies recede at a faster pace than the low-mids,

Think of a bass drum smacked right next to you vs. heard from across a large field. It goes from being perceived as a crack to more of a dull thud. By having the low-mids appear first (and recede last) you might get a different interplay between patterns than you would from a straight-up volume curve.

You could automate a high pass and low pass filter to gradually modulate the frequency as tracks fade in and out. A little automation of a reverb with reflections would heighten the effect.

excellent ideas! a slight overlap in the background of one rhythm track to the next would probably work... i'll give it a try. some filtering is definitely do-able as well! (i wonder if reversion to some very basic pulse/beat in between would also work)

as to why:
i'm writing some code to generate music, mostly drone + rhythms.

as for 'why would i do that?' - i dunno. learning? coding is more fun than doing 'real' composition? somebody's got to do it?
SmokeyVW
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Registered: 06/13/06
Posts: 7145
Location: N/A
 
Re:Cross-Fade Percussion Tracks
Tuesday, September 11 2018 @ 04:51 AM CDT

maybe another approach is to gradually mutate the rhythm pattern
bud
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Registered: 06/17/05
Posts: 3859
Location: Brooklyn, NY USA
 
Re:Cross-Fade Percussion Tracks
Tuesday, September 11 2018 @ 11:22 AM CDT

What if you sampled a small piece of track A and looped it to create a subset rhythm (A.a)? Then do the same with track B using the same length of time, or not to create (B.b).
Cross fade the looped sample (A.a) with track A as you start to fade in the looped sample (B.b) followed by track B - ending with track B alone.
Similar to your idea of working with a dominant beat - but creating two that come closer to matching.

It's better to regret something you have done, than something you haven't done.
MikeRobinson
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Registered: 08/29/11
Posts: 839
Location: Chattanooga, TN United States
 
Re:Cross-Fade Percussion Tracks
Tuesday, September 11 2018 @ 12:58 PM CDT

To my way of thinking, your present cross-fade is probably destroying the illusion of the perceived down-beat that, you say, is not actually there.   You ear is left groping to re-establish the non-existent beat.   Since it can’t, the perception is that of a cacophony.   And I’m not sure that you can do anything about it, so long as the downbeat is illusory.

Maybe your randomized rhythm tracks should contain a bona-fide downbeat ... some instrument that isn’t randomized.   Then, even if the part was taken up by another instrument in the faded-to track, your ear would simply perceive it to be a change of rhythm.
SmokeyVW
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Registered: 06/13/06
Posts: 7145
Location: N/A
 
Re:Cross-Fade Percussion Tracks
Tuesday, September 11 2018 @ 03:44 PM CDT

today's experiments with mutation seem to be working rather well. gradual changes seem to be working nicely: individual notes swap from one instrument to another, and/or shift slightly in time. the loudness gets gradually adjusted up or down as well.

i have an unsolved issue with notes that move across measure boundaries, but that should be fixable.
MikeRobinson
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Registered: 08/29/11
Posts: 839
Location: Chattanooga, TN United States
 
Re:Cross-Fade Percussion Tracks
Tuesday, September 11 2018 @ 06:45 PM CDT

In many ways, the brain is “a pattern-finding and pattern-discriminating machine.”   This is what enables you to “instinctively, at a glance,” detect that there might be a tiger lurking in yonder bush.   If your brain expects to find pattern in a mathematically-random stream of percussion sounds, it will somehow find one.   But it probably won’t take too kindly if that pattern subsequently fails.

Your experiments sound extremely interesting and I hope that you will post some actual examples of your tracks very soon.
SmokeyVW
Forum Full Member


Registered: 06/13/06
Posts: 7145
Location: N/A
 
Re:Cross-Fade Percussion Tracks
Wednesday, September 12 2018 @ 08:07 AM CDT

Quote by: MikeRobinson
In many ways, the brain is “a pattern-finding and pattern-discriminating machine.”   This is what enables you to “instinctively, at a glance,” detect that there might be a tiger lurking in yonder bush.   If your brain expects to find pattern in a mathematically-random stream of percussion sounds, it will somehow find one.   But it probably won’t take too kindly if that pattern subsequently fails.

Your experiments sound extremely interesting and I hope that you will post some actual examples of your tracks very soon.

yes indeed. i've been interested in the workings of the mind, and i have read about these things for many years. a lot of progress has been made, but there's a long way to go

pareidolia is a fascinating effect. i think a lot of the arts rely on it to work their magic. (Bob Ross comes to mind right now.) it's really cool how similar things can happen with artificial neural networks too.
see https://www.iflscience.com/technology/artificial-intelligence-dreams/

what i find truly frustrating is how learned people can know a lot about this topic, be subject themselves to its effects, and yet not believe it applies to them. i feel a lot of today's problems stem from exactly this

reality and perception are miles apart
 
SmokeyVW
Forum Full Member


Registered: 06/13/06
Posts: 7145
Location: N/A
 
Re:Cross-Fade Percussion Tracks
Wednesday, September 12 2018 @ 05:23 PM CDT

the mutation approach is working great!

the main reason, i suspect, is that it builds upon what the listener's interpretation is. why should i, in software, try to create, enforce, or discover, what "the beat" is? mutation gradually changes the temporal meaning of sounds, allowing the listener to gradually adapt to the sounds they are hearing. that ought to be truly "listener independent" - perhaps timeless

and on to the next issue...

i'll likely post on SoundCloud whatever comes of this. i can't post songs here any more. they come up as "This song is not yet approved"