Merge pull request #7989 from litetex/refactor-playback-parameter-dialog

Rewrote ``PlaybackParameterDialog``

app/src/main/java/org/schabi/newpipe/player/helper/PlayerSemitoneHelper.java

@@ -0,0 +1,38 @@
+package org.schabi.newpipe.player.helper;
+
+/**
+ * Converts between percent and 12-tone equal temperament semitones.
+ * <br/>
+ * @see
+ * <a href="https://en.wikipedia.org/wiki/Equal_temperament#Twelve-tone_equal_temperament">
+ *     Wikipedia: Equal temperament#Twelve-tone equal temperament
+ * </a>
+ */
+public final class PlayerSemitoneHelper {
+    public static final int SEMITONE_COUNT = 12;
+
+    private PlayerSemitoneHelper() {
+        // No impl
+    }
+
+    public static String formatPitchSemitones(final double percent) {
+        return formatPitchSemitones(percentToSemitones(percent));
+    }
+
+    public static String formatPitchSemitones(final int semitones) {
+        return semitones > 0 ? "+" + semitones : "" + semitones;
+    }
+
+    public static double semitonesToPercent(final int semitones) {
+        return Math.pow(2, ensureSemitonesInRange(semitones) / (double) SEMITONE_COUNT);
+    }
+
+    public static int percentToSemitones(final double percent) {
+        return ensureSemitonesInRange(
+                (int) Math.round(SEMITONE_COUNT * Math.log(percent) / Math.log(2)));
+    }
+
+    private static int ensureSemitonesInRange(final int semitones) {
+        return Math.max(-SEMITONE_COUNT, Math.min(SEMITONE_COUNT, semitones));
+    }
+}