koobas.hobune.stream
how to normalize a value to a range between 0 and 1
Hi - I'm doing an audio experiment where recording the sound coming out of my speakers gives me a number between around 0 and 20. I want to convert this number to something between 0 and 1, so that I can translate the volume level gets translated to the scale of an object. How do I do this? My basic setup is:
var audioVal:float = audio.GetOutPutData(...); //gives the audio in decibels
var scaleVal:float; //this value will give a scale between 0 and 1;
scaleVal = Mathf.Clamp(audioVal,0,1); //this doesn't seem to work. The value always ends up being at the maximum or minimum end of the scale.
Just divide by 20, or you can use Mathf.InverseLerp for arbitrary ranges. Clamp won't work because it just clamps numbers, it doesn't try to scale anything.
http://answers.unity3d.com/questions/1012209/algorithm-help.html
Similar question, answered with Clamp.
Mathf.Clamp() does not scale a value; it restricts the value to the range. For example, if you clamp between (0, 1), any value greater than 1 will yield a clamped value of 1, and any value less than zero will yield zero; for a value inside the clamp range, the value will be unchanged.
To scale, you need to divide your raw value by the total range, and account for an offset if min != 0. For a range of (min, max):
scaledValue = (rawValue - min) / (max - min);
For the common case where min == 0:
scaledValue = rawValue / max;
In a case where max could be theoretically infinite, should I just use an arbitrary big number as a max value?
@TechSupportInco$$anonymous$$g1:
It makes no sense to map an unbounded value to a bounded range. If "1.0" should represent infinity and "0.0" represent "0", then all values would mathematically map to "0.0".
Think about a real world example: temperature. The temperature has a lower bound of 0 kelvin (-273.15 °C) but is unbounded at the top. Why would you want to map an arbitrary temperature into the range of [0.0, 1.0]. All commonly used temperatures would be zero or extremely close to zero. So even temperatures around 1 million kelvin would result to be almost 0.
In such cases you might use a non linear mapping like (1/x) or log():
v1 = 1f - 1f / (1f+t);
That's the mapping of the first values:
t v1 v2
-----------------------------
0 0 0
1 0.5 0.00990
2 0.66666 0.01960
3 0.75 0.02912
4 0.8 0.03846
5 0.83333 0,04761
6 0.85714 0.05660
42 0.97674 0.29577
100 0.99009 0.5
333 0.99699 0.76905
1234 0.99919 0.92503
+inf 1.0 1.0
As you can see the values between 0 - 1 are mapped to 0-0.5 and the values between 1 - infinity is mapped to 0.5-1.0. If you need a better resolution for values around 100 you can either divide t by 100 beforehead or use 100f ins$$anonymous$$d of 1f:
v2 = 1f - 100f / (100f+t)
This will make 100 to map to 0.5
Here's a google link to that formula. You should see a graph at the top. make sure you zoom appropriately.
It makes no sense to map an unbounded value to a bounded range
(You might need to in a shader)
@Bunny83 thanks for the elaborate and scientific answer :)
If the range you're getting is exactly between 0 and 20, then replace your third line with:
scaleVal = audioVal / 20.0;
The code you're using isn't working because Mathf.Clamp merely restricts values to the range given, rather than doing a transformation from one space to another.
Just in case you want to stop at some point, this code works just perfectly for that!!!
var scaledValue = Mathf.Clamp(value / maxValue, minValue, maxValue);
Enjoy
This makes no sense. Since "value" is supposed between $$anonymous$$Value and maxValue, dividing value by maxValue gives you a range of 0-1. Clamping that range between $$anonymous$$ and max makes no sense. Also your lower bound would be wrong. You don't seem to be interested in a 0-1 range but in a $$anonymous$$Value to maxValue range which was not asked in the question. Scaling by maxValue makes no sense at all. There are cases where something like this is wanted:
$$anonymous$$athf.Clamp(value * scale, $$anonymous$$Value, maxValue);
where scale controls the scaling and clamp just limits the outcome to a certain range. However as I said this has nothing to do with the question that was asked.
