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summing signals + exponential curves

December 11, 2010 | 10:53 am

Hi all.

Is there a MSP version of expr? I need to sum about 6 signals together.

Also, what is the best way to convert a midi stream (0-127) to an exponential curve to control a meter such as a volume slider?

thanks


December 11, 2010 | 11:06 am

I’m sure I recall seeing a thread related to your first question; search for expr + msp, or expr + signal.

As for the second, I found this use of [expr], but cannot recall the author:

Attachments:
  1. midiGain.jpg

December 11, 2010 | 2:09 pm

That was me I think. In this case something like the following patch might be easier though. Change the [pow] argument and mess with the slider to hear the effects.

– Pasted Max Patch, click to expand. –

December 11, 2010 | 4:29 pm

the volume slider is as linear as midi, no need to scale.


December 11, 2010 | 6:14 pm

Here’s something much like Luke’s solution, but using the decibel scale.

– Pasted Max Patch, click to expand. –

December 12, 2010 | 10:47 pm

You could also take a look at the jcom.map and jcom.dataspace externals, part of Jamoma:

http://www.jamoma.org


December 13, 2010 | 2:04 am

btw, about your first question, you can sum signals using any MSP object, just
connect 6 signals to one inlet and thats it.


December 13, 2010 | 11:34 am

I recall that someone made an attempt at an [expr~] object in the very early days of MSP, but it was CPU-intensive and very crash-prone.

There’s nothing you can do with expr (or an expr~) that you can’t do by patching together mathematical objects. Although this can be a bit of work with complex formulae, at least it works.


December 13, 2010 | 11:51 am

Graham Wakefield’s [expr~] is here: http://www.maxobjects.com/?v=objects&id_objet=3882&PHPSESSID=9bf789a2a537a8e545113274f8d34ef6

It might be the same one peter mentioned though; haven’t used it myself


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