Auto Volume

need a feature, suggest here

Auto Volume

Postby Broomy » Sat Sep 19, 2015 12:06 pm

On my good ol' Gt-6 I have a preset called: Slow Gear
One of the features is that the volume swells when a note is played, similar to an autowah only then with volume.

This would be a great feature to get synth strings - like sounds, without having to use a footpedal (for those who have none or are to lazy too connect one... :roll: ).

Hans
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Re: Auto Volume

Postby Broomy » Tue Sep 29, 2015 6:50 pm

Allright,

I would like to take a shot making this plugin myself.
But, I will need some advice and encouragement.
Where do I start?
My guess is that this effect is somewhat a merge of the "auto-wah" and the "Volume", right?
Where the auto-way is waiting for an soundinput to give his "wah", this plugin would then turn up the volume.

There will be some different things, e.g. the volume has to be turned down before it can be turned up again (duhh...), when does it do so?

But first things first, I will try to check if I can make some out the code of the two plugins.

What do you guys think?

btw. it will be a long-term project

Hans
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Re: Auto Volume

Postby brummer10 » Tue Sep 29, 2015 7:31 pm

Hi Hans

Cool, I'm glade to see you digging into the source.
Unfortunately I'm overloaded currently with my work, but, I'll try to find some time on weekend to give you some advice from were to start, and how to build guitarix plugins. On first advice I could give, we use FAUST for most of our plugs,
http://faust.grame.fr/

Experiment with this language will help a lot in the first run (and it's a lot of fun, indeed, to work with the included examples from the faust source).
We've scripts included in our source (tools directory), which will build and install guitarix plugins directly from faust sources, so you'll have quick results to play within guitarix.

regards
hermann
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Re: Auto Volume

Postby Broomy » Wed Sep 30, 2015 7:38 pm

I've installed FaustWorks and checked some video's.
Is it wise to compile FaustWorks from Git or use the repro version?

I imported the autowah.dsp file and it cannot find the guitar.lib...

I look onto it tomorrow!

Hans
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Re: Auto Volume

Postby Broomy » Sat Oct 03, 2015 8:19 pm

I think I have enough info for now to digest.
My plan is:
Create the plugin in Faust and use the appropriate tool from the "tools" directory to create a plugin.

As for the plugin:
As a default the output volume of the plugin is 0, but when the plugin gets triggered by the incoming signal the volume gradually gets turned up to the level of the incoming signal.
But what then?
Does the volume of the output need to be turned down when the input signal gets under a certain level?

If so then there are 4 variables to deal with:
1. The treshold to turn the volume up
2. How fast the volume turns up
3. The treshold to turn the volume down
4. How fast the volume turns down.

so
if incoming signal x is => "treshold 1",
then turn volume up from 0 to "level signal x" in "amount of time 1",
until level signal x =< "treshold 2"
then turn volume down from "level signal x" to 0 in "amount of time 2"
Else then volume = 0

Am I on the right track?
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Re: Auto Volume

Postby brummer10 » Sun Oct 04, 2015 9:08 am

What you describe here, sounds more like a noise-gate, then a auto-volume.
https://en.wikipedia.org/wiki/Noise_gate

For coming closer to the "wah" effect, you should use the
amp_follower_ud
from the faust effect.lib to drive your volume settings.
(You'll find a noise-gate direct behind the amp_follower in effect.lib

regards
hermann
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Re: Auto Volume

Postby boomshop » Sun Oct 04, 2015 10:25 am

You need a factor to multiply the original signal with, default of this factor is 1. An envelope follower with adjustable attack and release times (in milliseconds, perhaps up to about 5 seconds) determines the actual average level and is used to calculate the factor to multiply the original signal. Additionally a slowly working noise gate is needed to prevent the device raising background noise to 0dB, so signals below ~36dB (0.015625) shouldn't be raised. A second (adjustable) factor might be used to lower the range of the overall manipulation.
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Re: Auto Volume

Postby Broomy » Sun Oct 04, 2015 2:09 pm

Alright thanks for the replies.
I want to take some time to get the hang and feel of Faust.

Please bare with me, because this is a completely new world for me:
I'm able to create a .dsp file using FaustWorks.
What steps do I have to take to create an actual plugin which I can select in Guitarix?
This way I can see/hear what happens when I change things.

My guess is:
1. Create a Guitarixplugin be using the "build-faust" command from the tools directory
2. Copying the created .so file to somewhere?
3. Rebuild Guitarix?


Am I right?

Thanks in advance.

Hans
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Re: Auto Volume

Postby brummer10 » Mon Oct 05, 2015 2:10 am

Broomy wrote:My guess is:
1. Create a Guitarixplugin be using the "build-faust" command from the tools directory
2. Copying the created .so file to somewhere?
3. Rebuild Guitarix?


Am I right?


You can use the build-faust script with the -c option, this will install (copy) the module into ~/.config/guitarix/plugins
The builded module is a shared library (plugin), no rebuild of guitarix is needed, just start guitarix and it will load the plugin.
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Re: Auto Volume

Postby Broomy » Sun Oct 18, 2015 7:32 pm

I think I have a solution: I imported the AbGate from the LV2 plugins. When I set the attack on 500ms it kinda gives a autovolume effect. Cool!

I'll try to make a cool preset and will post it.

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