Add configuration options for volume normalisation.

README.md

@@ -44,6 +44,8 @@ onevent = command_run_on_playback_events
 device_name = name_in_spotify_connect
 bitrate = 96|160|320
 cache = cache_directory
+volume-normalisation = true
+normalisation-pregain = -10
 ```
 Every field is optional, `Spotifyd` can even run without a configuration file.
 Options can also be placed in a `[spotifyd]` section, which takes priority over

src/cli.rs

@@ -25,6 +25,17 @@ pub fn command_line_argument_options() -> Options {
     opts.optopt("", "device_name", "Name of this Spotify device.", "DEVICE");
     opts.optopt("", "backend", "Audio backend.", "BACKEND");
     opts.optopt("", "cache_path", "Path to cache location.", "PATH");
+    opts.optflag(
+        "",
+        "volume-normalisation",
+        "Apply volume normalisation per track.",
+    );
+    opts.optopt(
+        "",
+        "normalisation-pregain",
+        "dB of pregain for volume normalisation",
+        "PREGAIN",
+    );
     opts.optopt(
         "",
         "onevent",

src/config.rs

@@ -163,6 +163,19 @@ pub fn get_config<P: AsRef<Path>>(config_path: Option<P>, matches: &Matches) ->
         }
     });
     config.onevent = lookup("onevent");
+    config.player_config.normalisation = matches.opt_present("volume-normalisation")
+        || spotifyd
+            .and_then(|s| s.get("volume-normalisation").map(String::clone))
+            .or_else(|| global.and_then(|g| g.get("volume-normalisation").map(String::clone)))
+            .unwrap_or("false".to_string()) == "true";
+
+    config.player_config.normalisation_pregain = lookup("normalisation-pregain")
+        .map(|db| {
+            db.parse::<f32>()
+                .expect("volume-normalisation must be a floating point number.")
+        })
+        .unwrap_or(PlayerConfig::default().normalisation_pregain);
+
     update(
         &mut config.player_config.bitrate,
         lookup("bitrate").and_then(|s| Bitrate::from_str(&*s).ok()),