Introduction

Flutter is a popular framework for building natively compiled applications for mobile, web, and desktop from a single codebase. One of the powerful tools for integrating real-time communication in mobile apps is LiveKit—a real-time video and audio streaming library. However, when building apps with LiveKit in Flutter, users may run into audio streaming issues, especially with iOS devices. One common error is the AVAudioSession issue.

This error can prevent audio from functioning properly during a LiveKit stream on iOS, leaving developers frustrated. Fortunately, by understanding the root cause and how to properly configure your AVAudioSession settings, you can resolve this issue and get your audio streaming back on track.

Understanding the AVAudioSession Error

The AVAudioSession is a class in iOS that manages the audio behavior for your app. It controls how your app interacts with the device's audio system and helps determine whether the app can play audio, record audio, or use audio features like VoiceOver or Bluetooth.

In Flutter LiveKit, improper configuration of the AVAudioSession can lead to audio errors when streaming. Specifically, issues arise when the audio session is not activated correctly or when its category and mode settings are incorrect.

Common causes for this issue:

• The audio session isn't activated.
• The wrong audio session category or mode is selected.
• The session conflicts with other apps using audio.

How to Fix the AVAudioSession Error in Flutter LiveKit

1. Ensure AVAudioSession is Properly Configured:

In Flutter, when working with LiveKit, you must ensure that the AVAudioSession is properly configured before starting any audio stream. This is usually done by setting the audio session category and mode to the appropriate values for your use case.

Below is an example of setting up the AVAudioSession correctly:

import 'package:flutter/services.dart'; import 'package:flutter_audio_session/flutter_audio_session.dart'; Future<void> configureAudioSession() async {  final session = await FlutterAudioSession.instance;  await session.configure(    AudioSessionConfiguration.speech(),  ); }

• AudioSessionConfiguration.speech() is ideal for live audio streaming, as it configures the session for audio playback and recording. You can adjust this configuration based on whether you need background audio or the ability to play or record.
• You can also specify other categories like playback, recording, etc., depending on the nature of your app.

2. Activate the AVAudioSession:

Before starting audio streaming with LiveKit, make sure the session is properly activated. You can do this by calling:

final session = await FlutterAudioSession.instance; await session.setActive(true);

This step ensures that the audio session is ready for use when your app starts streaming.

3. Set the Correct Mode:

Depending on your requirements, you may need to set the mode of the audio session. For example, if you are streaming live audio (like in a video call), you might want to set the mode to modeVoiceChat: 

await session.setMode(AudioSessionMode.voiceChat);

This helps ensure that the audio session is optimized for live communication, providing better performance and compatibility with Flutter LiveKit.

4. Handle Audio Interruptions:

Audio interruptions (such as incoming calls) may disrupt the session, which could cause the AVAudioSession error. To handle this, you can listen for interruptions and resume the audio session when appropriate. 

session.interruptionEventStream.listen((event) {  if (event.type == AudioInterruptionType.ended) {    session.setActive(true);  } });

This allows the audio session to recover if interrupted, improving the reliability of your LiveKit streaming experience.

5. Test on Real Devices:

Always test audio streaming on a real iOS device. The AVAudioSession behaves differently on simulators, and using a real device ensures that your configuration is correct.

Conclusion

The AVAudioSession error can be a major hurdle when working with Flutter LiveKit on iOS devices, but with the right configuration, it's easy to resolve. By ensuring that the audio session is correctly activated, configured, and set to the right mode, you can get your audio streaming back on track. Proper handling of audio interruptions and testing on real devices are also key to achieving a smooth experience.

By following these steps, you can ensure that your Flutter app with LiveKit provides reliable and high-quality audio streaming for your users.