Custom audio source

The default audio module of Video SDK meets the need of using basic audio functions in your app. For adding advanced audio functions, Video SDK supports using custom audio sources and custom audio rendering modules.

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

• Your app has its own audio module.
• You need to process the captured audio with a pre-processing library for audio enhancement.
• You need flexible device resource allocation to avoid conflicts with other services.

This page shows you how to capture and render audio from custom sources.

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

The following figure illustrates the process of custom audio capture.

• You implement the capture module using external methods provided by the SDK.
• You call pushExternalAudioFrame to send the captured audio frames to the SDK.

The following figure illustrates the process of custom audio rendering.

• You implement the rendering module using external methods provided by the SDK.
• You call pullPlaybackAudioFrame to retrieve the audio data sent by remote users.

Ensure that you have implemented the SDK quickstart in your project.

This section shows you how to implement custom audio capture and render audio from a custom source.

Refer to the following call sequence diagram to implement custom audio capture in your app:

Follow these steps to implement custom audio capture in your project:

1. Before calling joinChannel, use setExternalAudioSource to enable and configure your custom audio source.

   
   

   _7

   // Specify the custom audio source

   _7

   engine.setExternalAudioSource(true, DEFAULT_SAMPLE_RATE, DEFAULT_CHANNEL_COUNT, 1, true, true);

   _7

   // Join the channel for the local user

   _7

   ChannelMediaOptions option = new ChannelMediaOptions();

   _7

   option.autoSubscribeAudio = true;

   _7

   option.autoSubscribeVideo = true;

   _7

   int res = engine.joinChannel(accessToken, channelId, 0, option);

   
   

2. Implement audio capture and processing using external SDK methods.

3. Call pushExternalAudioFrame to send audio frames to the SDK.

   
   

   _1

   engine.pushExternalAudioFrame(ByteBuffer.wrap(buffer), 0, 0);

   
   

This section shows you how to implement custom audio rendering. Refer to the following call sequence diagram to implement custom audio rendering in your app:

To implement custom audio rendering, use the following methods:

1. Before calling joinChannel, use setExternalAudioSink to enable and configure custom audio rendering.

   
   

   _5

   rtcEngine.setExternalAudioSink(

   _5

   true, // Enable custom audio rendering

   _5

   44100, // Sampling rate (Hz). Set this value to 16000, 32000, 441000, or 48000

   _5

   1 // Number of channels for the custom audio source. Set this value to 1 or 2

   _5

   );

   
   

2. After joining the channel, call pullPlaybackAudioFrame to get audio data sent by remote users. Use your own audio renderer to process the audio data and then play the rendered data.

   
   

   _20

   private class FileThread implements Runnable {

   _20

   _20

   @Override

   _20

   public void run() {

   _20

   while (mPull) {

   _20

   int lengthInByte = 48000 / 1000 * 2 * 1 * 10;

   _20

   ByteBuffer frame = ByteBuffer.allocateDirect(lengthInByte);

   _20

   int ret = engine.pullPlaybackAudioFrame(frame, lengthInByte);

   _20

   byte[] data = new byte[frame.remaining()];

   _20

   frame.get(data, 0, data.length);

   _20

   // Write to a local file or render using a player

   _20

   FileIOUtils.writeFileFromBytesByChannel("/sdcard/agora/pull_48k.pcm", data, true, true);

   _20

   try {

   _20

   Thread.sleep(10);

   _20

   } catch (InterruptedException e) {

   _20

   e.printStackTrace();

   _20

   }

   _20

   }

   _20

   }

   _20

   }

   
   

This section explains how to implement custom audio rendering.

To retrieve audio data for playback, implement collection and processing of raw audio data. Refer to Raw audio processing.

Follow these steps to call the raw audio data API in your project for custom audio rendering:

1. Retrieve audio data for playback using the onRecordAudioFrame, onPlaybackAudioFrame, onMixedAudioFrame, or onPlaybackAudioFrameBeforeMixing callback.

2. Independently render and play the audio data.

This section explains how to implement different sound effects and audio mixing in your app, covering essential steps and code snippets.

Agora provides the following open-source sample projects for audio self-capture and audio self-rendering for your reference:

• CustomAudioSource
• CustomAudioRender

• setExternalAudioSource [1/2]
• setExternalAudioSource [2/2]
• pushExternalAudioFrame
• setExternalAudioSink
• pullPlaybackAudioFrame [1/2]
• pullPlaybackAudioFrame [2/2]