make autoscale default

src/main.rs

@@ -33,6 +33,7 @@ impl Params {
                         };
                 }
                 "multiply" => {
+                    params.autoscale = false;
                     params.multiply = iter
                         .next()
                         .expect("multiply parameter expects a value.")
@@ -59,7 +60,7 @@ impl Default for Params {
             channel: 2,
             multiply: 5.0,
             integrate: false,
-            autoscale: false,
+            autoscale: true,
         }
     }
 }
@@ -81,10 +82,10 @@ invocation: `infraconv <input csv file> <input samples/s> <output wav file> [<ou
 output params are any as follows:
 
 - `speed <number>` speed multiplier: outputHz will be n * inputHz.
-- `multiply <number>` data multiplier: amplitude is multiplied by n. 5 is default.
+- `multiply <number>` data multiplier: amplitude is multiplied by n. autoscale is default.
 - `channel <x|y|z>` specifies which accelerometer channel to covert. z is default.
 - `integrate` sets integration mode, where the input is integrated first to enhance low frequencies that may not be picked up correctly.
-- `autoscale` automatically sets the multiplier based on the input.
+- `autoscale` automatically sets the multiplier based on the input. (this is the default. parameter is still accepted for compatibility)
 
 when using integrate mode, multiply may need to be set to a lower number.\
         "
@@ -114,7 +115,10 @@ when using integrate mode, multiply may need to be set to a lower number.\
     }
 
     if params.autoscale {
-        params.multiply = 1.0 / get_scale(&samples);
+        let scale = get_scale(&samples);
+        if scale > 0.0 {
+            params.multiply = 1.0 / scale;
+        }
     }
     println!("infraconv: Multiply = {}", params.multiply);