feat(player): add volume boost with automatic real-time gain

app/src/main/java/org/schabi/newpipe/player/Player.java

@@ -30,9 +30,12 @@
 import static com.google.android.exoplayer2.Player.RepeatMode;
 import static org.schabi.newpipe.extractor.ServiceList.YouTube;
 import static org.schabi.newpipe.extractor.utils.Utils.isNullOrEmpty;
+import static org.schabi.newpipe.player.helper.PlayerHelper.retrieveAutoVolumeBoostFromPrefs;
 import static org.schabi.newpipe.player.helper.PlayerHelper.retrievePlaybackParametersFromPrefs;
 import static org.schabi.newpipe.player.helper.PlayerHelper.retrieveSeekDurationFromPreferences;
+import static org.schabi.newpipe.player.helper.PlayerHelper.retrieveVolumeBoostFromPrefs;
 import static org.schabi.newpipe.player.helper.PlayerHelper.savePlaybackParametersToPrefs;
+import static org.schabi.newpipe.player.helper.PlayerHelper.saveVolumeBoostToPrefs;
 import static org.schabi.newpipe.player.notification.NotificationConstants.ACTION_CLOSE;
 import static org.schabi.newpipe.player.notification.NotificationConstants.ACTION_FAST_FORWARD;
 import static org.schabi.newpipe.player.notification.NotificationConstants.ACTION_FAST_REWIND;
@@ -67,7 +70,6 @@
 import androidx.preference.PreferenceManager;
 
 import com.google.android.exoplayer2.C;
-import com.google.android.exoplayer2.DefaultRenderersFactory;
 import com.google.android.exoplayer2.ExoPlayer;
 import com.google.android.exoplayer2.PlaybackException;
 import com.google.android.exoplayer2.PlaybackParameters;
@@ -102,6 +104,7 @@
 import org.schabi.newpipe.player.helper.LoadController;
 import org.schabi.newpipe.player.helper.PlayerDataSource;
 import org.schabi.newpipe.player.helper.PlayerHelper;
+import org.schabi.newpipe.player.helper.VolumeBoostRenderersFactory;
 import org.schabi.newpipe.player.mediaitem.MediaItemTag;
 import org.schabi.newpipe.player.mediasession.MediaSessionPlayerUi;
 import org.schabi.newpipe.player.notification.NotificationPlayerUi;
@@ -214,7 +217,7 @@ public final class Player implements PlaybackListener, Listener {
     @NonNull
     private final LoadController loadController;
     @NonNull
-    private final DefaultRenderersFactory renderFactory;
+    private final VolumeBoostRenderersFactory renderFactory;
 
     @NonNull
     private final VideoPlaybackResolver videoResolver;
@@ -299,7 +302,8 @@ public Player(@NonNull final PlayerService service,
         renderFactory = prefs.getBoolean(
                 context.getString(
                         R.string.always_use_exoplayer_set_output_surface_workaround_key), false)
-                ? new CustomRenderersFactory(context) : new DefaultRenderersFactory(context);
+                ? new CustomRenderersFactory(context)
+                : new VolumeBoostRenderersFactory(context);
 
         renderFactory.setEnableDecoderFallback(
                 prefs.getBoolean(
@@ -607,6 +611,8 @@ private void initPlayback(@NonNull final PlayQueue queue,
                 R.string.playback_skip_silence_key), getPlaybackSkipSilence());
         final PlaybackParameters savedParameters = retrievePlaybackParametersFromPrefs(this);
         setPlaybackParameters(savedParameters.speed, savedParameters.pitch, playbackSkipSilence);
+        setVolumeBoost(retrieveVolumeBoostFromPrefs(this),
+                retrieveAutoVolumeBoostFromPrefs(this));
 
         playQueue = queue;
         playQueue.init();
@@ -966,6 +972,32 @@ public boolean getPlaybackSkipSilence() {
         return !exoPlayerIsNull() && simpleExoPlayer.getSkipSilenceEnabled();
     }
 
+    public float getVolumeBoost() {
+        return renderFactory.getVolumeBoost();
+    }
+
+    public boolean isAutoVolumeBoostEnabled() {
+        return renderFactory.isAutomaticVolumeBoost();
+    }
+
+    /**
+     * Sets how much the decoded audio should be amplified, and also saves it to shared
+     * preferences. The gain is rounded up to 2 decimal places before being used or saved.
+     *
+     * @param volumeBoost     the gain to apply when {@code autoVolumeBoost} is disabled, where 1
+     *                        means no amplification at all
+     * @param autoVolumeBoost whether the gain should instead be computed in real time from the
+     *                        loudness of the stream being played
+     */
+    public void setVolumeBoost(final float volumeBoost, final boolean autoVolumeBoost) {
+        final float roundedVolumeBoost = Math.round(volumeBoost * 100.0f) / 100.0f;
+
+        saveVolumeBoostToPrefs(this, roundedVolumeBoost, autoVolumeBoost);
+        renderFactory.setVolumeBoost(roundedVolumeBoost);
+        renderFactory.setAutomaticVolumeBoost(autoVolumeBoost);
+        UIs.call(PlayerUi::onVolumeBoostChanged);
+    }
+
     public PlaybackParameters getPlaybackParameters() {
         if (exoPlayerIsNull()) {
             return PlaybackParameters.DEFAULT;

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

@@ -3,24 +3,23 @@
 import android.content.Context;
 import android.os.Handler;
 
-import com.google.android.exoplayer2.DefaultRenderersFactory;
 import com.google.android.exoplayer2.Renderer;
 import com.google.android.exoplayer2.mediacodec.MediaCodecSelector;
 import com.google.android.exoplayer2.video.VideoRendererEventListener;
 
 import java.util.ArrayList;
 
 /**
- * A {@link DefaultRenderersFactory} which only uses {@link CustomMediaCodecVideoRenderer} as an
- * implementation of video codec renders.
+ * A {@link VolumeBoostRenderersFactory} which only uses {@link CustomMediaCodecVideoRenderer} as
+ * an implementation of video codec renders.
  *
  * <p>
  * As no ExoPlayer extension is currently used, the reflection code used by ExoPlayer to try to
  * load video extension libraries is not needed in our case and has been removed. This should be
  * changed in the case an extension is shipped with the app, such as the AV1 one.
  * </p>
  */
-public final class CustomRenderersFactory extends DefaultRenderersFactory {
+public final class CustomRenderersFactory extends VolumeBoostRenderersFactory {
 
     public CustomRenderersFactory(final Context context) {
         super(context);

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

@@ -454,6 +454,27 @@ public static void savePlaybackParametersToPrefs(final Player player,
                 .apply();
     }
 
+    public static float retrieveVolumeBoostFromPrefs(final Player player) {
+        return player.getPrefs().getFloat(player.getContext().getString(
+                R.string.playback_volume_boost_key), player.getVolumeBoost());
+    }
+
+    public static boolean retrieveAutoVolumeBoostFromPrefs(final Player player) {
+        return player.getPrefs().getBoolean(player.getContext().getString(
+                R.string.playback_auto_volume_boost_key), player.isAutoVolumeBoostEnabled());
+    }
+
+    public static void saveVolumeBoostToPrefs(final Player player,
+                                              final float volumeBoost,
+                                              final boolean autoVolumeBoost) {
+        player.getPrefs().edit()
+                .putFloat(player.getContext().getString(R.string.playback_volume_boost_key),
+                        volumeBoost)
+                .putBoolean(player.getContext().getString(R.string.playback_auto_volume_boost_key),
+                        autoVolumeBoost)
+                .apply();
+    }
+
     public static float getMinimumVideoHeight(final float width) {
         return width / (16.0f / 9.0f); // Respect the 16:9 ratio that most videos have
     }