Revert math::round_half_to_even

This caused quite a bump in CPU usage, which be acceptable if this
actually improved sound quality. However, it turns out that this
function only has one decimal precision, i.e. it would consider
all values from `0.50..0.60` (exclusive) as `0.5` which is in
error for our purposes.

Author: roderickvd

Cargo.lock

@@ -20,7 +20,6 @@ version = "0.2.0"
 [dependencies]
 futures-executor = "0.3"
 futures-util = { version = "0.3", default_features = false, features = ["alloc"] }
-libmath = "0.2"
 log = "0.4"
 byteorder = "1.4"
 shell-words = "1.0.0"
@@ -59,4 +58,4 @@ jackaudio-backend = ["jack"]
 rodio-backend = ["rodio", "cpal", "thiserror"]
 rodiojack-backend = ["rodio", "cpal/jack", "thiserror"]
 sdl-backend = ["sdl2"]
-gstreamer-backend = ["gstreamer", "gstreamer-app", "glib"]
+gstreamer-backend = ["gstreamer", "gstreamer-app", "glib"]

playback/Cargo.toml

@@ -63,8 +63,7 @@ impl Converter {
 
         // Casting float to integer rounds towards zero by default, i.e. it
         // truncates, and that generates larger error than rounding to nearest.
-        // Absolute lowest error is gained from rounding ties to even.
-        math::round::half_to_even(int_value, 0)
+        int_value.round()
     }
 
     // Special case for samples packed in a word of greater bit depth (e.g.