Merge pull request #488 from Rubecks/exponential-volume-plugin

New Plugin: Exponential Volume

plugins/exponential-volume/front.js

@@ -0,0 +1,47 @@
+// "Youtube Music fix volume ratio 0.4" by Marco Pfeiffer
+// https://greasyfork.org/en/scripts/397686-youtube-music-fix-volume-ratio/
+
+const exponentialVolume = () => {
+	// manipulation exponent, higher value = lower volume
+	// 3 is the value used by pulseaudio, which Barteks2x figured out this gist here: https://gist.github.com/Barteks2x/a4e189a36a10c159bb1644ffca21c02a
+	// 0.05 (or 5%) is the lowest you can select in the UI which with an exponent of 3 becomes 0.000125 or 0.0125%
+	const EXPONENT = 3;
+
+	const storedOriginalVolumes = new WeakMap();
+	const { get, set } = Object.getOwnPropertyDescriptor(
+		HTMLMediaElement.prototype,
+		"volume"
+	);
+	Object.defineProperty(HTMLMediaElement.prototype, "volume", {
+		get() {
+			const lowVolume = get.call(this);
+			const calculatedOriginalVolume = lowVolume ** (1 / EXPONENT);
+
+			// The calculated value has some accuracy issues which can lead to problems for implementations that expect exact values.
+			// To avoid this, I'll store the unmodified volume to return it when read here.
+			// This mostly solves the issue, but the initial read has no stored value and the volume can also change though external influences.
+			// To avoid ill effects, I check if the stored volume is somewhere in the same range as the calculated volume.
+			const storedOriginalVolume = storedOriginalVolumes.get(this);
+			const storedDeviation = Math.abs(
+				storedOriginalVolume - calculatedOriginalVolume
+			);
+
+			const originalVolume =
+				storedDeviation < 0.01
+					? storedOriginalVolume
+					: calculatedOriginalVolume;
+			return originalVolume;
+		},
+		set(originalVolume) {
+			const lowVolume = originalVolume ** EXPONENT;
+			storedOriginalVolumes.set(this, originalVolume);
+			set.call(this, lowVolume);
+		},
+	});
+};
+
+module.exports = () =>
+	document.addEventListener("apiLoaded", exponentialVolume, {
+		once: true,
+		passive: true,
+	});