[Resolved] How to crossfade between 4 tracks in realtime ?

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Hielo Patagonia Sounds
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[Resolved] How to crossfade between 4 tracks in realtime ?

Post by Hielo Patagonia Sounds » Wed Apr 14, 2010 12:08 am

Hello,

I've recorded 4 audio clips from my modular synth in 4 separate audio tracks. I'm wondering how to crossfade between 4 tracks in realtime using the joystick of my FaderFox micromodul LV2 ? A kind of vector mixing between these 4 tracks ?

What I've tried was to make some group tracks : Group Track 1 = Track A + Track C - Group Track 2 = Track B + Track D. Then I assigned the X MIDI controller of the FaderFox's joystick to control the level of track A and in opposite the level of track C. I did the same for Track B and D with the Y MIDI controller of the FaderFox's joystick. But that's not a true vector crossfader.

:x

I think that the X MIDI controller of the FaderFox's joystick should also control the level of the Group Track 2 and the same with the Y MIDI controller of the FaderFox's joystick for the level of the Group Track 1. But then the MIDI controllers values must be mapped to have a special curve ...

Any idea ????
Last edited by Hielo Patagonia Sounds on Wed Apr 14, 2010 11:42 am, edited 1 time in total.

yur2die4
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Re: How to crossfade between 4 tracks in realtime ?

Post by yur2die4 » Wed Apr 14, 2010 12:25 am

I tried an experiment. I used a Rack, but this can be applied to Channel volumes.

Within each rack I had assigned opposites of volume to knob 1. (-inf - +6, for rack A, +6 - -inf for rack B).

I then added a Utility to each rack. This is the tricky part, I set the Utility Gain knob to accomodate for the midpoint and the max point. With the +6 offset of the master Volume this ended up being something like this:

Rack A:
Main volume: -inf - +6
Utility Gain: 34 - -6

Rack B:
Main Volume: +6 - -inf
Utility Gain: -6 - 34

As you can see, as it hits -Inf, your Utility is up at 34, but you won't hear anything since you are mute. When you are at +6 gain, Utility compensates to bring it down to zero (I'm sure you can switch the 6's out for 0's, but then you would have to use 28 instead of 34, if you get my drift.

The midpoint of the volume slider was -14. The Utility (which is essentially set to Double 14) makes up for the loss :D

I don't know a lot about db theory.. but visually it seemed to check out :)

Hielo Patagonia Sounds
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Re: How to crossfade between 4 tracks in realtime ?

Post by Hielo Patagonia Sounds » Wed Apr 14, 2010 1:07 am

Thanks ! This should works for 2 audio sources but with 4 sources it's a more tricky ! :oops:

Any more ideas ... or should I go an buy Max For Live

yur2die4
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Re: How to crossfade between 4 tracks in realtime ?

Post by yur2die4 » Wed Apr 14, 2010 2:12 am

Well, if you use channels instead of racks, it works for 4.

The problem is, in that scenario Stick in center means having all 4 sources at once, at normal volume. Any direction you lean away from means you subtract volume from that source. Unfortunately, no matter what you are stuck with a minimum of 2 sources at once at any given time.

It seems a lot trickier to joystick 4 audio sources than what I used to do with my joystick (sending each channel of one mono source out to 4 returns, each of which went out to a different speaker). In that case, center was a quieter blend of audio when the joystick was at center. But any direction I pointed it, would increase. It also allowed for me to have full on sound in any one direction while actually having zero on 3 others. So that I would be able to listen to an individual soundsource.

Anyway, best of luck. I'll keep dwelling on ideas for this haha.

I'm wondering if phase cancellation would have any realistic use in this scenario..

Hielo Patagonia Sounds
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Re: How to crossfade between 4 tracks in realtime ?

Post by Hielo Patagonia Sounds » Wed Apr 14, 2010 2:38 am

More informations about vector synthesis here : http://en.wikipedia.org/wiki/Vector_synthesis

Hielo Patagonia Sounds
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Re: How to crossfade between 4 tracks in realtime ?

Post by Hielo Patagonia Sounds » Wed Apr 14, 2010 11:41 am

I've found a good trick this morning !!! :D

Instead of thinking about axis (X and Y) where each of the four audio sources is along these axis (axis X : source A & source C - axis Y : source B & source D), the idea was to think about a square where each corner is an audio source. Here is what I've done ...

1 - I cut my 4 loops to the same length (16 bars in this case) and put each on its own track.

2 - Right-click on each audio clip and convert them with "Slice in a new MIDI track".

Image


3 - Select the smaller resolution you can have (here 1/8 bar give 128 slices) and for Slice Preset select "Slice to simgle Sampler".

Image


4 - Now you should have 4 new MIDI tracks in which you have a single Sampler instrument playing a 16 bar MIDI loop triggering 128 sample slices of the former audio loops => Loop 1, Loop 2, Loop 3, Loop 4.

Image


5 - Create a new MIDI track, copy the first Sampler instrument in it (Loop 1), and copy the MIDI clip too.

6 - Create a rack with this Sampler instrument and copy in it the second Sampler instrument (from the 2d audio loop : Loop 1) => Rack 1-2 with MIDI triggered loops 1 & 2.

7 - Embedded Rack 1-2 into an new rack => Main Rack.

8 - Duplicate Rack 1-2 and rename the copy Rack 3-4.

9 - Copy into Rack 3-4 Sampler instruments Loop 3 and Loop 4, and delete Sampler instruments Loop 1 and Loop 2 which were copied when we have duplicated Rack 1-2 (see previous step 8).

10 - Now in each sub-racks (Rack 1-2 and Rack 3-4), click on the CHAIN button and draw a crossfade with respectively Loop 1 and Loop 2, and Loop 3 and Loop 4.

Image


11 - For each sub-racks (Rack 1-2 and Rack 3-4), assign a circular knob to control the crossfade between respectively Loop 1 and Loop 2, and Loop 3 and Loop 4.

12 - On the Main Rack assign a circular knob to control both knob from Rack 1-2 and Rack 3-4, and label it Fade X.

13 - On the Main Rack, click on the CHAIN button and draw a crossfade between Rack 1-2 and Rack 3-4 and assign a second circular knob to control the main crossfade. Label it Fade Y.

Image


14 - Assign MIDI controller to knobs b]Fade X[/b] and b]Fade Y[/b] and have fun !!! 8)

NOTES
- You should make some minors level adjustments in each of the 4 Sampler instruments to get a good audio balance.
- If you are using a MIDI joystick (I'm using the one in my Faderfox micromodul LV2), each corner is an audio source. Making circles with the joystick crossfade between the 4 audio sources.
- If you put the joystick in the central position, you may get a kind of "bad spot" audio level, but it depends on your audio materials too.

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