Granular Synth: How do the Scrub Mode and Set Playhead Time nodes work?

[Impossybleposslb]

@ZakBe

Hi Felix-
Good questions all around :). I’ll share my setup with how I created my granular demo (in this case dynamic water) for GDC to compare methods :).

First things though, is that Scrub Mode is (as I understand it) is for varispeed scrubbing (like a tape transport, going backwards and forwards with the option to alter playback rate/pitch). It’s not a granular scrubber; the granular player has this ability innately.
Also, looking at your Set Playhead Time, the In Position Sec is fine, but I see that your Lerp Time Sec is set to 1000 seconds. That means a Seek from the beginning (0 seconds) to your In Position Sec (5) will take 1000 seconds… quite a long time :). This might explain why your playhead isn’t ‘moving’, it may just be moving… very slow.
I also see your Grains per Second is 1000; this is pretty aggressive, and will result in more of a ‘wall of noise’ than an identifiable sound… consider orders of magnitude less.

That said, what you’re after should be possible. Here’s my setup that I used:
I’ve made a 12 second sound that goes from a water trickle up to a raging torrent of water (made in Reaper by crossfading content in 2 second chunks).

I’ve defined the variables like this:
Grain Duration: 600.0
Grain Attack Time: 20.0
Grain Relase Time: 400.0
Grains Per Second: 30.0
Grain Envelope Type: Hanning
Slider Value is a float I’m getting from an interface from another Blueprint (from a slider) that returns a value between 0 and 1.
BaseIntensity is just a remapping of the Slider Value float.

In my Event Tick setup, I’m remapping the BaseIntensity float to vary from 0 to 11, to correspond with 0 to 11 seconds of Playhead Time.
I’ve also introduced a plus or minus .5 second random position variance in the Playhead Time by adding a Random Float in Range.
I’ve also hard clamped the Playhead Time between 0 and 12 seconds, since that’s the length of the audio file.
(see granular_water_part1.jpg)

In the second half of my setup, I introduce Pitch, Volume, Pan, and Grains Per Second variability to make the audio sound more ‘alive’ and dynamic.
(see granular_water_part2.jpg)

The slider ingame moves the value of BaseIntensity from 0 to 1, and the Playback Time shifts around accordingly, even at a static position.

Here is a video of the slider moving the Playhead Time through the sound (and changing VFX with it):
Box

Hi! By any chance would there be a link to this demo project? I´m finding wrapping my head around the granular synth a bit challenging without documentation. Or maybe you know of another useful resource. Thanks in advance:)