Merge pull request #1051 from rafaelrpinto/feature/audio-panning

Added stereoPan property to allow audio panning

README.md

@@ -231,6 +231,7 @@ var styles = StyleSheet.create({
 * [repeat](#repeat)
 * [resizeMode](#resizemode)
 * [selectedTextTrack](#selectedtexttrack)
+* [stereoPan](#stereopan)
 * [volume](#volume)
 
 #### ignoreSilentSwitch
@@ -337,6 +338,14 @@ If a track matching the specified Type (and Value if appropriate) is unavailable
 
 Platforms: Android ExoPlayer, iOS
 
+#### stereoPan
+Adjust the balance of the left and right audio channels.  Any value between –1.0 and 1.0 is accepted.
+* **-1.0** - Full left
+* **0.0 (default)** - Center
+* **1.0** - Full right
+
+Platforms: Android MediaPlayer
+
 #### volume
 Adjust the volume.
 * **1.0 (default)** - Play at full volume

Video.js

@@ -284,6 +284,7 @@ Video.propTypes = {
   paused: PropTypes.bool,
   muted: PropTypes.bool,
   volume: PropTypes.number,
+  stereoPan: PropTypes.number,
   rate: PropTypes.number,
   playInBackground: PropTypes.bool,
   playWhenInactive: PropTypes.bool,

android/src/main/java/com/brentvatne/react/ReactVideoView.java

@@ -28,6 +28,7 @@ import java.io.IOException;
 import java.util.HashMap;
 import java.util.Map;
 import java.lang.Math;
+import java.math.BigDecimal;
 
 @SuppressLint("ViewConstructor")
 public class ReactVideoView extends ScalableVideoView implements MediaPlayer.OnPreparedListener, MediaPlayer
@@ -95,6 +96,7 @@ public class ReactVideoView extends ScalableVideoView implements MediaPlayer.OnP
     private boolean mPaused = false;
     private boolean mMuted = false;
     private float mVolume = 1.0f;
+    private float mStereoPan = 0.0f;
     private float mProgressUpdateInterval = 250.0f;
     private float mRate = 1.0f;
     private float mActiveRate = 1.0f;
@@ -359,6 +361,14 @@ public class ReactVideoView extends ScalableVideoView implements MediaPlayer.OnP
         }
     }
 
+    // reduces the volume based on stereoPan
+    private float calulateRelativeVolume() {
+        float relativeVolume = (mVolume * (1 - Math.abs(mStereoPan)));
+        // only one decimal allowed
+        BigDecimal roundRelativeVolume = new BigDecimal(relativeVolume).setScale(1, BigDecimal.ROUND_HALF_UP);
+        return roundRelativeVolume.floatValue();
+    }
+
     public void setMutedModifier(final boolean muted) {
         mMuted = muted;
 
@@ -368,7 +378,14 @@ public class ReactVideoView extends ScalableVideoView implements MediaPlayer.OnP
 
         if (mMuted) {
             setVolume(0, 0);
+        } else if (mStereoPan < 0) {
+            // louder on the left channel
+            setVolume(mVolume, calulateRelativeVolume());
+        } else if (mStereoPan > 0) {
+            // louder on the right channel
+            setVolume(calulateRelativeVolume(), mVolume);
         } else {
+            // same volume on both channels
             setVolume(mVolume, mVolume);
         }
     }
@@ -378,6 +395,11 @@ public class ReactVideoView extends ScalableVideoView implements MediaPlayer.OnP
         setMutedModifier(mMuted);
     }
 
+    public void setStereoPan(final float stereoPan) {
+        mStereoPan = stereoPan;
+        setMutedModifier(mMuted);
+    }
+
     public void setProgressUpdateInterval(final float progressUpdateInterval) {
         mProgressUpdateInterval = progressUpdateInterval;
     }

android/src/main/java/com/brentvatne/react/ReactVideoViewManager.java

@@ -30,6 +30,7 @@ public class ReactVideoViewManager extends SimpleViewManager<ReactVideoView> {
     public static final String PROP_PAUSED = "paused";
     public static final String PROP_MUTED = "muted";
     public static final String PROP_VOLUME = "volume";
+    public static final String PROP_STEREO_PAN = "stereoPan";
     public static final String PROP_PROGRESS_UPDATE_INTERVAL = "progressUpdateInterval";
     public static final String PROP_SEEK = "seek";
     public static final String PROP_RATE = "rate";
@@ -124,6 +125,11 @@ public class ReactVideoViewManager extends SimpleViewManager<ReactVideoView> {
         videoView.setVolumeModifier(volume);
     }
 
+    @ReactProp(name = PROP_STEREO_PAN)
+    public void setStereoPan(final ReactVideoView videoView, final float stereoPan) {
+        videoView.setStereoPan(stereoPan);
+    }
+
     @ReactProp(name = PROP_PROGRESS_UPDATE_INTERVAL, defaultFloat = 250.0f)
     public void setProgressUpdateInterval(final ReactVideoView videoView, final float progressUpdateInterval) {
         videoView.setProgressUpdateInterval(progressUpdateInterval);