# New Zynthian User Guide -\> mapping

**URL:** <https://discourse.zynthian.org/t/new-zynthian-user-guide-mapping/4306>\
**Category:** Using Zynthian\
**Created:** [June 8, 2020, 12:08pm UTC](https://discourse.zynthian.org/t/new-zynthian-user-guide-mapping/4306 "2020-06-08T12:08:57Z")\
**Posts on this page:** 8\
**Page:** 1

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**Author:** ![Micki](https://discourse.zynthian.org/user_avatar/discourse.zynthian.org/micki/32/3872_2.png) [@Micki](https://discourse.zynthian.org/u/Micki)\
**Post date:** [June 8, 2020, 12:08pm UTC](https://discourse.zynthian.org/t/new-zynthian-user-guide-mapping/4306/1 "2020-06-08T12:08:57Z")

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Hi,  
thanx for the new Zynthian User Guide. Iǘe seen, that there are many issues i don know. Zynthian keeps an adventure 😉

One thing: I miss the declarations for admin/midi profile/mapping.  
I have the problem, that a keyboard sends allways high velocity values. So I want to reduce the velocity eg by factor 0.8. Is it possible to map that?

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**Author:** ![Micki](https://discourse.zynthian.org/user_avatar/discourse.zynthian.org/micki/32/3872_2.png) [@Micki](https://discourse.zynthian.org/u/Micki)\
**Post date:** [June 9, 2020, 2:26pm UTC](https://discourse.zynthian.org/t/new-zynthian-user-guide-mapping/4306/2 "2020-06-09T14:26:36Z")

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Ok, i’ve found the midi filter rules in the zynthian wiki using the search button. If I want to change note events, i can change the channel and the note on/off value.  
@jofemodo: Is it possible to implement a command to change the velocity of note on events?  
Regards

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**Author:** ![jofemodo](https://discourse.zynthian.org/user_avatar/discourse.zynthian.org/jofemodo/32/2_2.png) [@jofemodo](https://discourse.zynthian.org/u/jofemodo)\
**Post date:** [June 13, 2020, 10:56pm UTC](https://discourse.zynthian.org/t/new-zynthian-user-guide-mapping/4306/3 "2020-06-13T22:56:56Z")

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Hi Micki!

Have you tried to use the new MIDI-chain feature?  
If you want to adjust velocity, you could simply add to your layers some of the available MIDI tools, like:

- MIDI Velocity Adjust
- MIDI Velocity Gamma
- MIDI Velocity Randomization
- MIDI Velocity-Range Filter

You should enable the MIDI plugins you want from the webconf LV2-Plugins panel.

Regards,

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**Author:** ![Micki](https://discourse.zynthian.org/user_avatar/discourse.zynthian.org/micki/32/3872_2.png) [@Micki](https://discourse.zynthian.org/u/Micki)\
**Post date:** [July 2, 2020, 2:46pm UTC](https://discourse.zynthian.org/t/new-zynthian-user-guide-mapping/4306/4 "2020-07-02T14:46:20Z")

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@jofemodo: Hi Jose, today I tried the Miditools. With the 1st step I used only the velocity adjustment: wonderful!!! The next days I will try more. Lot of thanx from Düsseldorf !!! 💐

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**Author:** ![MrBroccoli](https://discourse.zynthian.org/user_avatar/discourse.zynthian.org/mrbroccoli/32/3195_2.png) [@MrBroccoli](https://discourse.zynthian.org/u/MrBroccoli)\
**Post date:** [July 3, 2020, 1:51am UTC](https://discourse.zynthian.org/t/new-zynthian-user-guide-mapping/4306/5 "2020-07-03T01:51:07Z")

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My drum chain now includes a 1 or 2 % velocity variance via randomisation and it really makes a difference on a disco beat or anything straight like that.

What is gamma?

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**Author:** ![wyleu](https://discourse.zynthian.org/user_avatar/discourse.zynthian.org/wyleu/32/514_2.png) [@wyleu](https://discourse.zynthian.org/u/wyleu)\
**Post date:** [July 3, 2020, 7:09am UTC](https://discourse.zynthian.org/t/new-zynthian-user-guide-mapping/4306/6 "2020-07-03T07:09:11Z")

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> [@MrBroccoli](#):
>
> gamma

Sort of a distorted transfer function. It was originally used in TV cameras to partially match the characteristics of the eye, basically it’s the amount of curve in the graph…

> **[Gamma correction](https://en.wikipedia.org/wiki/Gamma_correction)**
>
> Gamma correction or gamma is a nonlinear operation used to encode and decode luminance or tristimulus values in video or still image systems. Gamma correction is, in the simplest cases, defined by the following power-law expression:
> where the non-negative real input value 
>   
>     
>       
>         
> V
>           
> in
>           
>         
>       
>     
> {\\displaystyle V\_{\\text{in}}}
>   
> is raised to the power 
>   
>     
>       
> γ
>       
>     
> {\\displaystyle \\gamma }
>   
> a...

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**Author:** ![jofemodo](https://discourse.zynthian.org/user_avatar/discourse.zynthian.org/jofemodo/32/2_2.png) [@jofemodo](https://discourse.zynthian.org/u/jofemodo)\
**Post date:** [July 3, 2020, 1:44pm UTC](https://discourse.zynthian.org/t/new-zynthian-user-guide-mapping/4306/7 "2020-07-03T13:44:19Z")

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I suppose @MrBroccoli means the “velocity gamma” LV2 plugin, from X42. The description from github page says:

> Velocity Gamma – modify note velocity curve by a gamma exponent

And as Mr @wyleu points, it probably makes something similar to what is used for image gamma correction, using a “power law” like this:

Vout=Vin^Gamma

for modifying the velocity curve so it’s less sensitive to differences on the lower range.

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**Author:** ![MrBroccoli](https://discourse.zynthian.org/user_avatar/discourse.zynthian.org/mrbroccoli/32/3195_2.png) [@MrBroccoli](https://discourse.zynthian.org/u/MrBroccoli)\
**Post date:** [July 3, 2020, 6:33pm UTC](https://discourse.zynthian.org/t/new-zynthian-user-guide-mapping/4306/8 "2020-07-03T18:33:52Z")

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> [@jofemodo](#):
>
> Vout=Vin^Gamma

Yes but what is the gamma half life? 😂👍

(Thanks, you answered my question)