Fix safari volume being reset when track changed (#5923)

Author: gnattu

src/plugins/htmlAudioPlayer/plugin.js

@@ -124,13 +124,17 @@ class HtmlAudioPlayer {
                 }
 
                 if (normalizationGain) {
-                    self.gainNode.gain.value = Math.pow(10, normalizationGain / 20);
-                    self.normalizationGain = self.gainNode.gain.value;
+                    self.normalizationGain = Math.pow(10, normalizationGain / 20);
+                    self.gainNode.gain.value = self.normalizationGain;
                 } else {
                     self.gainNode.gain.value = 1;
                     self.normalizationGain = 1;
                 }
-                console.debug('gain: ' + self.gainNode.gain.value);
+                if (browser.safari) {
+                    // Gain value is absolute in Safari. Add volume from the slider
+                    self.gainNode.gain.value *= elem.volume;
+                }
+                console.debug('gain: ' + self.normalizationGain);
             }).catch((err) => {
                 console.error('Failed to add/change gainNode', err);
             });