Easy Video Editing and Delivery for the Android ExoPlayer: A Tutorial

ExoPlayer, a media player for Android, was developed and is being maintained by Google as an alternative for Android’s default MediaPlayer. Among ExoPlayer’s advantages over MediaPlayer are dynamic adaptive streaming over HTTP (DASH), smooth streaming, and common encryption. A major advantage, however, is ExoPlayer’s easy customization.

Given the mobile constraints for resources, such as videos, ExoPlayer is an excellent choice for playing videos in Android apps because of its video-buffering capability, which downloads videos ahead of time for a seamless experience. You can play videos with ExoPlayer from phone storage or from URLs, as described later in this tutorial.

Through an Android example app for ExoPlayer, this tutorial shows you how to leverage Cloudinary, a cloud-based service platform on which you can upload rich media for cloud storage as well as efficiently and effectively manage and transform them, in order to seamlessly display videos on ExoPlayer.

Uploading and Transforming Videos

With Cloudinary, you can transform videos by simply tweaking their URLs. Cloudinary then delivers the videos through fast Content Delivery Networks (CDNs) with advanced caching techniques.

Follow the steps below to upload and transform videos in Cloudinary.

1. Replace CLOUDINARY_NAME in the AndroidManifest.xml file with your cloud name, which is displayed in the console of your Cloudinary account:

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   <meta-data
   android:name="CLOUDINARY_URL"
   android:value="cloudinary://@CLOUDINARY_NAME"/>

2. Create an application class to initialize Cloudinary once for the app’s entire lifecycle. Given this one-time initialization, the global variables usually reside in this class.

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   import android.app.Application;
   import com.cloudinary.android.MediaManager;
   public class AppController extends Application {
   @Override
   public void onCreate() {
       super.onCreate();
       // Initialize Cloudinary
       MediaManager.init(this);
   }
   }

3. Also in the AndroidManifest.xml file, specify AppController as the name of the application tag:

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   <application
   android:name=".AppController" >

   Note

   Your uploads can be unsigned or signed. Signed uploads, which offer certain benefits, require an API key, which is not recommended for Android clients because it can be easily decompiled. Hence, opt for unsigned upload here.

4. Enable unsigned uploads in your console: click the Settings icon on your dashboard and then the Upload tab, scroll down to the Upload Presets section, and enable unsigned uploading. Cloudinary then generates a new preset with a random string as its name.

5. Upload to Cloudinary by calling this function:

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   MediaManager.get()
       .upload(videoUri)
       .unsigned("YOUR_PRESET")
       .option("resource_type", "video")
       .callback(new UploadCallback() {
           @Override
           public void onStart(String requestId) {
   
           }
   
           @Override
           public void onProgress(String requestId, long bytes, long totalBytes) {
   
           }
   
           @Override
           public void onSuccess(String requestId, Map resultData) {
   
           }
   
           @Override
           public void onError(String requestId, ErrorInfo error) {
   
           }
   
           @Override
           public void onReschedule(String requestId, ErrorInfo error) {
   
           }
       }).dispatch();

videoUri is of type Uri, which represents the Uniform Resource Identifier (URI) of the video that resides in your phone, e.g., content://media/external/video/media/3495.

On a successful upload, Cloudinary calls the onSuccess method, which contains the details of your upload, such as URL (the URL) and public_url (the public URL), which is the unique name of the video as stored in Cloudinary.

Next, transform the video in the method below by referring to public_url:

String publicUrl = = (String) resultData.get("public_url");
String transformedUrl = MediaManager.get().url()
        .transformation(new Transformation()
                .effect("fade:2000").chain()
                .effect("fade:-3000").chain()
                .effect("saturation:-50")
        .resourceType("video").generate(publicUrl+".mp4");

You’ve now added three effects to the video:

• A two-second fade-in. Fade-ins usually have a positive value.
• A three-second fade-out. Fade-outs usually have a negative value.
• A drop in the saturation. A negative saturation value results in a faded look of the video.

A printout of transformedUrl reads like this: https://res.cloudinary.com/{CLOUD_NAME}/video/upload/e_fade:2000/e_fade:-3000/e_saturation:-50/{publicUrl}.mp4

For details on Cloudinary’s many transformation capabilities, see this section in a Cloudinary post. To learn about video transformations on Cloudinary, see the related documentation.

Setting Up ExoPlayer for Android Apps

It is assumed that you have developed an Android app, hence this section does not address that process. Follow the steps below to set up ExoPlayer for your app:

1. Add the Gradle dependency to your build.gradle file to make use of the ExoPlayer library:

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   implementation 'com.google.android.exoplayer:exoplayer:2.6.0'

   Note

   If your Gradle version is below 3.0, replace implementation in the above snippet with compile.

2. Sync your gradle file to ensure a download of the dependency for the project.

3. Add SimpleExoPlayerView to your Activity layout:

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   <?xml version="1.0" encoding="utf-8"?>
   <LinearLayout xmlns:android="https://schemas.android.com/apk/res/android"
   xmlns:tools="https://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="180dp"
   android:layout_margin="16dp">
   
   <com.google.android.exoplayer2.ui.SimpleExoPlayerView
       android:id="@+id/exoplayer"
       android:layout_width="match_parent"
       android:layout_height="wrap_content"/>

4. In the onStart method in the corresponding Activity class, initialize SimpleExoPlayerView and set up SimpleExoPlayer by calling the initializePlayer method:

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   @Override
   protected void onStart() {
   super.onStart();
   initializePlayer();
   }

   initializePlayer applies the default configurations for a seamless display of videos in ExoPlayer:

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   private void initializePlayer(){
   // Create a default TrackSelector
   BandwidthMeter bandwidthMeter = new DefaultBandwidthMeter();
   TrackSelection.Factory videoTrackSelectionFactory =
           new AdaptiveTrackSelection.Factory(bandwidthMeter);
   TrackSelector trackSelector =
           new DefaultTrackSelector(videoTrackSelectionFactory);
   
   //Initialize the player
   player = ExoPlayerFactory.newSimpleInstance(this, trackSelector);
   
   //Initialize simpleExoPlayerView
   SimpleExoPlayerView simpleExoPlayerView = findViewById(R.id.exoplayer);
   simpleExoPlayerView.setPlayer(player);
   
   // Produces DataSource instances through which media data is loaded.
   DataSource.Factory dataSourceFactory =
           new DefaultDataSourceFactory(this, Util.getUserAgent(this, "CloudinaryExoplayer"));
   
   // Produces Extractor instances for parsing the media data.
   ExtractorsFactory extractorsFactory = new DefaultExtractorsFactory();
   
   // This is the MediaSource representing the media to be played.
   Uri videoUri = Uri.parse("any Cloudinary URL");
   MediaSource videoSource = new ExtractorMediaSource(videoUri,
           dataSourceFactory, extractorsFactory, null, null);
   
   // Prepare the player with the source.
   player.prepare(videoSource);
   
   }

The above snippet performs these tasks:

• Initializes the SimpleExoPlayer instance with the default configurations.
• Creates and initializes an instance of SimpleExoPlayerView and assigns your existing player instance to it.
• Generates the media source with videoUri parsed from a video URL (URL) from Cloudinary.

Now prepare the player with the video source, after which the video is ready for display. You now have a basic implementation of ExoPlayer.

5. To save resources, add the code below to release the player when it’s not in use:

```java

@Override public void onPause() { super.onPause(); if (player!=null) { player.release(); player = null; } } ```

Finally, add the permissions for the app to access the internet in the AndroidManifest.xml file :

<uses-permission android:name="android.permission.INTERNET"/>

The app looks like this if you play the transformed URL with ExoPlayer.

Exploring Cloudinary Further

You can integrate Cloudinary, which offers robust capabilities for video management, with libraries like ExoPlayer to display videos on Android apps. It’s an intuitive, easy process. For details on optimizing videos with Cloudinary, see this post. Also see the Cloudinary documentation for other media-management features.

Want to Learn More About Video Optimization?

• Optimizing Video with Cloudinary and the HTML5 Video Player
• ExoPlayer Android Tutorial: Easy Video Delivery and Editing
• How to Generate Waveform Images From Audio Files
• Auto Generate Subtitles Based on Video Transcript
• Automated Generation of Intelligent Video Previews on Cloudinary’s Dynamic Video Platform
• Converting Android Videos to Animated GIF Images With Cloudinary: A Tutorial
• Tips for Retaining Audience Through Engaging Videos
• Product Videos 101: What Makes Them Great?