# Midi In & Valuebox: -12 to +12 with message.int_value

midi input message.int_value

4 replies to this topic

### #1 Raul (ulneiz)

Raul (ulneiz)

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Posted 04 February 2018 - 13:10

Hi. I have created a valuebox that returns a value within the following range: -12 to +12

Through the midi_mapping of the vaulebox I have done the following:

name = "Tools:PhraseTouch:Panel_1:Transpose:Transpose Valuebox",
invoke = function( message )
if message:is_abs_value() then
vws["PHT_VAL_TRANS_1"].value = math.min( 12, math.max( message.int_value - 12, -12 ) )
end
end
}

math.min( 12, math.max( message.int_value - 12, -12 ) ) return returns the correct range, which is exactly this:

-12, -11 ... -2, -1, 00, 01, 02 ... +11, +12

The problem is that I can not return the correct range to fit the range of a rotating wheel, which is from 0 to 127. "0 to 127" corresponds to the value of "message.int_value".

Ok, I have tried to do the following:

math.min( 12, math.max( (message.int_value/(128/25) -12 ), -12 ) )

name = "Tools:PhraseTouch:Panel_1:Transpose:Transpose Valuebox",
invoke = function( message )
if message:is_abs_value() then
vws["PHT_VAL_TRANS_1"].value = math.min( 12, math.max( message.int_value/(128/25) - 12, -12 ) )
end
end
}

...but this returns the next range:

-12, -11 ... -2, -1, -0, 00, 01, 02 ... +11, +12

The operation also returns a "-0" a value that should not be. If you change the divisor to any other number, there always appears a 0 that should not be, -0 or +0, but should only return a "0" (neither negative nor positive).

Is there a different way to achieve this correctly? The intention is that the rotating wheel turns completely (-12 left, 0 up center, +12 right).

To be exact, this is the complete range that I want to return:

-12, -11, -10, -9, -8, -7, -6, -5, -4, -3, -2, -1, 00, 01, 02, 03, 04, 05, 06, 07, 08, 09, 10, 11, 12

Note: I also use tostring and tonumber to adjust the values of the valuebox. But the problem is in the message.int_value of the midi_mapping

Edited by Raul (ulneiz), 04 February 2018 - 16:50.

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### #2 4Tey

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Posted 04 February 2018 - 16:02

Personally I'd write maybe:

value = math.floor((message.int_value * 0.1875) + 0.5) - 12

where I assume message.int_value takes values through 0 to 127 and value gets values -12 to 12 but that probably isn't what you are looking for anyway.  Just sayin' Raul.

### #3 joule

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Posted 04 February 2018 - 16:42

With the risk of me misunderstanding.. If you want to "convert a value from one range to another", here is the formula: https://stackoverflo...intaining-ratio

### #4 Raul (ulneiz)

Raul (ulneiz)

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Posted 04 February 2018 - 16:44

@4Tey. Ok, work perfectly! With math.floor you use a multiplier 24/128 = 0.1875.

I would have thought 25 instead of 24, because from -12 to +12 there are 25 values, counting 0. But no, they must be 24. Or 25/127. But no, they must be 24/128.

Thank you very much 4Tey!!!

@Joule. Thanks! All this information is very useful for specific mathematics. Sometimes I have trouble looking for certain things that are in English. Thanks for the link!

...

Edited by Raul (ulneiz), 04 February 2018 - 16:51.

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### #5 Raul (ulneiz)

Raul (ulneiz)

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Posted 05 February 2018 - 02:11

value = math.floor( message.int_value * 25/128 ) - 12

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