Custom audio sources

By default, Video SDK uses the basic audio and video modules on the device your app runs on. However, there are certain scenarios where you want to integrate a custom audio or video source into your app, such as:

• Your app has its own audio or video module.
• You want to use a non-camera source, such as recorded screen data.
• You need to process the captured audio or video with a pre-processing library for audio or image enhancement.
• You need flexible device resource allocation to avoid conflicts with other services.

To set an external audio or video source, you configure the Agora Engine before joining a channel. To manage the capture and processing of audio and video frames, you use methods from outside the Video SDK that are specific to your custom source. Video SDK enables you to push processed audio and video data to the subscribers in a channel.

The figure below shows the workflow you need to implement to stream a custom video or audio source in your app.

To follow this procedure you must have implemented the SDK quickstart project for Voice Calling.

To create the environment necessary to implement custom audio and video into your app, open the SDK quickstart Voice Calling project you created previously.

To stream from a custom source, you convert the data stream into a suitable format and push this data using Video SDK.

In this section you create the basic framework required to push video frames from a custom source. Depending on the type of your source, you add your own code to this framework that converts the source data to VideoFrame data. To create the basic framework, take the following steps:

1. Import the required Agora and Android libraries

   You use the Android TextureView and SurfaceTexture objects for rendering custom video. The video data from the SurfaceTexture is converted to a VideoFrame before it is pushed to the channel. To use these libraries in your app, add the following statements after the last import statement in /app/java/com.example.<projectname>/MainActivity.

   
   

   _4

   import io.agora.base.VideoFrame;

   _4

   import android.graphics.SurfaceTexture;

   _4

   import android.view.TextureView;

   _4

   import androidx.annotation.NonNull;

   
   

2. Define variables to process and push video data

   In /app/java/com.example.<ProductWrapper>/MainActivity, add the following declarations to the MainActivity class:

   
   

   _5

   private TextureView previewTextureView;

   _5

   private SurfaceTexture previewSurfaceTexture;

   _5

   _5

   private boolean mTextureDestroyed = false;

   _5

   private boolean mPreviewing = false;

   
   

3. Enable custom video track publishing

   When a user presses Join, you configure ChannelMediaOptions to enable publishing of the captured video from a custom source. You set the external video source, and set up a TextureView for the custom video preview. To do this:

   1. Add the following lines to the joinChannel(View view) method in the MainActivity class after ChannelMediaOptions options = new ChannelMediaOptions();:

      
      

      _11

      // Enable publishing of the captured video from a custom source

      _11

      options.publishCustomVideoTrack = true;

      _11

      // Configure the external video source.

      _11

      agoraEngine.setExternalVideoSource(true, true, Constants.ExternalVideoSourceType.VIDEO_FRAME);

      _11

      // Check whether texture encoding is supported

      _11

      showMessage(agoraEngine.isTextureEncodeSupported() ? "Texture encoding is supported" :

      _11

      "Texture encoding is not supported");

      _11

      // Set up a preview TextureView for the custom video

      _11

      setupCustomLocalVideoPreview();

      _11

      // Show the preview TextureView

      _11

      previewTextureView.setVisibility(View.VISIBLE);

      
      

   2. In the joinChannel(View view) method, remove the following lines:

      
      

      _2

      setupLocalVideo();

      _2

      localSurfaceView.setVisibility(View.VISIBLE);

      
      

4. Set up a TextureView for the custom video

   Create a new TextureView object, and add a SurfaceTextureListener to it. The listener triggers the onSurfaceTextureAvailable callback when a SurfaceTexture becomes available. You add the TextureView to the FrameLayout container to display it in the UI. To do this, add the following method to the MainActivity class:

   
   

   _9

   private void setupCustomLocalVideoPreview() {

   _9

   // Create TextureView

   _9

   previewTextureView = new TextureView(getBaseContext());

   _9

   // Add a SurfaceTextureListener

   _9

   previewTextureView.setSurfaceTextureListener(surfaceTextureListener);

   _9

   // Add the TextureView to the local video FrameLayout

   _9

   FrameLayout container = findViewById(R.id.local_video_view_container);

   _9

   container.addView(previewTextureView,320,240);

   _9

   }

   
   

5. Define the SurfaceTextureListener

   When a SurfaceTexture becomes available, you create a previewSurfaceTexture and set its onFrameAvailableListener listener. You set up and configure your custom video source, set its SurfaceTexture to the previewSurfaceTexture, and start the preview. To do this, add the following definition of the surfaceTextureListener to the MainActivity class:

   
   

   _39

   private final TextureView.SurfaceTextureListener surfaceTextureListener = new TextureView.SurfaceTextureListener(){

   _39

   @Override

   _39

   public void onSurfaceTextureAvailable(@NonNull SurfaceTexture surface, int width, int height) {

   _39

   // Invoked when a TextureView's SurfaceTexture is ready for use.

   _39

   _39

   if (mPreviewing) {

   _39

   // Already previewing custom video

   _39

   return;

   _39

   }

   _39

   _39

   showMessage("Surface Texture Available");

   _39

   mTextureDestroyed = false;

   _39

   _39

   // Set up previewSurfaceTexture

   _39

   previewSurfaceTexture = new SurfaceTexture(true);

   _39

   previewSurfaceTexture.setOnFrameAvailableListener(onFrameAvailableListener);

   _39

   _39

   // Add code here to set up and configure the custom video source

   _39

   // Add code here to set SurfaceTexture of the custom video source to previewSurfaceTexture

   _39

   _39

   // Start preview

   _39

   mPreviewing = true;

   _39

   }

   _39

   _39

   @Override

   _39

   public void onSurfaceTextureSizeChanged(@NonNull SurfaceTexture surface, int width, int height) {

   _39

   }

   _39

   _39

   @Override

   _39

   public boolean onSurfaceTextureDestroyed(@NonNull SurfaceTexture surface) {

   _39

   mTextureDestroyed = true;

   _39

   return false;

   _39

   }

   _39

   _39

   @Override

   _39

   public void onSurfaceTextureUpdated(@NonNull SurfaceTexture surface) {

   _39

   _39

   }

   _39

   };

   
   

6. Push the video frames

   The onFrameAvailableListener callback is triggered when a new video frame is available. In the callback, you convert the SurfaceTexture data to a Video SDK VideoFrame and push the frame to the channel. To do this, add the following OnFrameAvailableListener to the MainActivity class:

   
   

   _16

   private final SurfaceTexture.OnFrameAvailableListener onFrameAvailableListener = new SurfaceTexture.OnFrameAvailableListener() {

   _16

   @Override

   _16

   public void onFrameAvailable(SurfaceTexture surfaceTexture) {

   _16

   // Callback to notify that a new stream video frame is available.

   _16

   _16

   if (isJoined) {

   _16

   // Configure the external video frames and send them to the SDK

   _16

   VideoFrame videoFrame = null;

   _16

   _16

   // Add code here to convert the surfaceTexture data to a VideoFrame object

   _16

   _16

   // Send VideoFrame to the SDK

   _16

   agoraEngine.pushExternalVideoFrame(videoFrame);

   _16

   }

   _16

   }

   _16

   };

   
   

To push audio from a custom source to a channel, take the following steps:

1. Import the required Android and Java libraries

   You use an InputStream to read the contents of the custom audio source. The app starts a separate Process to read and push the audio data. To use these libraries in your app, add the following statements after the last import statement in /app/java/com.example.<projectname>/MainActivity.

   
   

   _3

   import android.os.Process;

   _3

   import java.io.InputStream;

   _3

   import java.io.IOException;

   
   

2. Define variables to manage and push the audio stream

   In /app/java/com.example.<projectname>/MainActivity, add the following declarations to the MainActivity class:

   
   

   _12

   // Audio file parameters

   _12

   private static final String AUDIO_FILE = "applause.wav"; // raw audio file

   _12

   private static final Integer SAMPLE_RATE = 44100;

   _12

   private static final Integer SAMPLE_NUM_OF_CHANNEL = 2;

   _12

   private static final Integer BITS_PER_SAMPLE = 16;

   _12

   private static final Integer SAMPLES = 441;

   _12

   private static final Integer BUFFER_SIZE = SAMPLES * BITS_PER_SAMPLE / 8 * SAMPLE_NUM_OF_CHANNEL;

   _12

   private static final Integer PUSH_INTERVAL = SAMPLES * 1000 / SAMPLE_RATE;

   _12

   _12

   private InputStream inputStream;

   _12

   private Thread pushingTask = new Thread(new PushingTask());

   _12

   private boolean pushing = false;

   
   

3. Add a raw audio file to the project

   In this example, you use an audio file as the source of your custom audio data. To add the audio file to your Android project, create a folder app\src\main\assets and add a sample audio file in *.wav or *.raw format to this folder. Update the value of the AUDIO_FILE variable to show the audio file name. Also make sure that the values of the audio file parameters in your code match the audio file you placed in the assets folder.

4. Enable custom audio track publishing

   When a user presses Join, you set the ChannelMediaOptions to disable the microphone audio track and enable the custom audio track. You also enable custom audio local playback and set the external audio source. To do this, add the following lines to the joinChannel(View view) method in the MainActivity class after options.clientRoleType = Constants.CLIENT_ROLE_BROADCASTER;:

   
   

   _6

   options.publishMicrophoneTrack = false; // Disable publishing microphone audio

   _6

   options.publishCustomAudioTrack = true; // Enable publishing custom audio

   _6

   options.enableAudioRecordingOrPlayout = true;

   _6

   _6

   agoraEngine.enableCustomAudioLocalPlayback(0, true);

   _6

   agoraEngine.setExternalAudioSource(true, SAMPLE_RATE, SAMPLE_NUM_OF_CHANNEL, 2, false, true);

   
   

5. Open the audio file

   When the app starts, you open the audio file. To do this, add the following lines at the bottom of the onCreate method:

   
   

   _5

   try {

   _5

   inputStream = this.getResources().getAssets().open(AUDIO_FILE);

   _5

   } catch (IOException e) {

   _5

   e.printStackTrace();

   _5

   }

   
   

6. Start the task to push audio frames

   When a user successfully joins a channel, you start the task that pushes audio frames. To do this, add the following lines at the bottom of the onJoinChannelSuccess callback in the MainActivity class:

   
   

   _2

   pushing = true;

   _2

   pushingTask.start();

   
   

7. Read the input stream into a buffer

   You read data from the input stream into a buffer. To do this, add the following method to the MainActivity class:

   
   

   _13

   private byte[] readBuffer() {

   _13

   int byteSize = BUFFER_SIZE;

   _13

   byte[] buffer = new byte[byteSize];

   _13

   try {

   _13

   if (inputStream.read(buffer) < 0) {

   _13

   inputStream.reset();

   _13

   return readBuffer();

   _13

   }

   _13

   } catch (IOException e) {

   _13

   e.printStackTrace();

   _13

   }

   _13

   return buffer;

   _13

   }

   
   

8. Push the audio frames

   You push the data in the buffer as an audio frame using a separate process. To do this, define the following Runnable class in the MainActivity class:

   
   

   _20

   class PushingTask implements Runnable {

   _20

   long number = 0;

   _20

   _20

   @Override

   _20

   public void run() {

   _20

   Process.setThreadPriority(Process.THREAD_PRIORITY_URGENT_AUDIO);

   _20

   while (pushing) {

   _20

   long before = System.currentTimeMillis();

   _20

   agoraEngine.pushExternalAudioFrame(readBuffer(), 0);

   _20

   long now = System.currentTimeMillis();

   _20

   long consuming = now - before;

   _20

   if(consuming < PUSH_INTERVAL){

   _20

   try {

   _20

   Thread.sleep(PUSH_INTERVAL - consuming);

   _20

   } catch (InterruptedException e) {

   _20

   }

   _20

   }

   _20

   }

   _20

   }

   _20

   }

   
   

9. Close the audio file

   When the app is closed, you close the audio file. To do this, add the following lines at the bottom of the onDestroy method:

   
   

   _5

   try {

   _5

   inputStream.close();

   _5

   } catch (IOException e) {

   _5

   e.printStackTrace();

   _5

   }

   
   

To ensure that you have implemented streaming from a custom source into your app:

1. Generate a temporary token in Agora Console

2. Add authentication data to the web demo

   In your browser, navigate to the Agora web demo and update App ID, Channel, and Token with the values for your temporary token, then click Join.

3. In Android Studio, open app/java/com.example.<projectname>/MainActivity, and update appId, channelName and token with the values for your temporary token.

4. Connect a physical Android device to your development device.

5. In Android Studio, click Run app. A moment later you see the project installed on your device.

   If this is the first time you run the project, grant microphone and camera access to your app.

6. Test the custom video source

   Add code to the basic framework presented above, to do the following:

   1. In onSurfaceTextureAvailable enable the video source and set its parameters.

   2. In onSurfaceTextureAvailable set SurfaceTexture of the custom video source to previewSurfaceTexture.

   3. In onFrameAvailable convert surfaceTexture data to a VideoFrame.

6. Test the custom audio source

   Press Join. You hear the audio file streamed to the web demo app.

   To use this code for streaming data from your particular custom audio source, modify the readBuffer() method to read the audio data from your source, instead of a raw audio file.

This section contains information that completes the information in this page, or points you to documentation that explains other aspects to this product.

• setExternalVideoSource
• pushExternalVideoFrame
• isTextureEncodeSupported

• setExternalAudioSource
• pushExternalAudioFrame