I need to make an 8 band peak meter for a jitter overlay on some video so I was trying to search the forums for a simple example of how to draw one as a jitter matrix, and am challenged by knowing nothing about MSP or audio processing. I found a few things and ended up with a patcher that uses fffb~ to cut the audio up into different frequency "blocks" that I can use to visualize any sound fed from fffb~ into 8 meter~ objects placed right next to each other and it looks pretty good.
So I took a parallel path and sent the same data going to each meter~ obj and put it into a peakmeter~ object, clipped it from 0. to 1., and I'm trying to draw rectangles (black on white) using mgraphics by using the 0. to 1. value and scaling each rectangle to the height of my matrix. This does work, but when I put it next to the clumped together meter~ objs, my mgraphics example has "flatter" values then the meter~ objs. (the two examples move together when processing the same audio, but the meter~ objs scale better). So I guess meter~ scales the raw values (the ones it reports itself in its outlet) using some exponential curve when drawing the visual display of colored boxes.
Do I just need to play with the scale obj, for instance, until I find the right exponential value so that my mgraphics version matches my meter~ version or is there some commonly known or documented way that meter~ uses to take the (linear 0 to 1) signal values and map them to visually to light up the colored boxes?
(As a side note, I do not need accuracy in recording these values, I'm not doing anything with the audio data other than trying to "visualize it" in standard "graphic equalizer look" as video overlay, and for now the clump of meter~ objs more compelling visualize the audio then my mgraphics matrix). Thx!