Fixing One-Way Audio Problems with 1:1.NET MAUI Calls Using Azure Communication Services Handles

Solving Audio Challenges in Mobile 1:1 Calls with Azure Communication Services

Developing a robust 1:1 video call feature can present unique challenges, especially when integrating services like Azure Communication Services (ACS) into a .NET MAUI application. One common issue that developers face is one-way audio during calls, where the callee can hear the caller, but the caller cannot hear the callee.

This issue can be particularly frustrating when everything else works fine, including two-way video and audio on desktop or certain mobile devices. Addressing the audio issue requires a deep dive into the configuration of permissions, device management, and microphone selection on mobile platforms.

The problem is especially noticeable when handling audio streams with JavaScript while integrating ACS. Even with correct implementation of the call setup, remote audio streaming, and device permissions, unexpected one-way audio can occur, complicating the development process.

In this article, we'll explore troubleshooting techniques for one-way audio issues in 1:1 calls using .NET MAUI and Azure Communication Services. We'll go through microphone selection, participant subscription, and device permissions to ensure a smooth, two-way communication experience in your mobile app.

Command	Example of use
askDevicePermission()	This command is used to explicitly request permissions for audio and video access from the user in the Azure Communication Services context. It ensures that the app can capture and transmit audio and video during the call.
getMediaStream()	Part of the RemoteAudioStream interface, this command retrieves the actual media stream object for remote audio. It's essential for handling and playing back remote audio streams during a call.
on('remoteParticipantsUpdated')	An event handler that tracks changes in the remote participants, such as when new participants are added or removed from the call. This command is critical for maintaining real-time updates on remote users during a 1:1 call.
startCall()	Initializes and starts the 1:1 call between participants. This command ensures that the audio and video streams are correctly initiated and that the correct configuration for audio permissions is applied.
subscribeToRemoteParticipant()	This function subscribes to events related to a specific remote participant, including their audio and video streams. It's crucial for ensuring that changes in the participant’s state, such as muting or stream availability, are handled correctly.
onAudioStreamsUpdated	An event listener attached to remote participants that detects changes in their audio streams. This command ensures that if the remote participant starts or stops transmitting audio, the local user is updated accordingly.
selectBestMicrophone()	This custom function filters through available microphones and selects the best one for the call, ensuring that the correct audio input is being used for optimal audio quality during the call.
createCallAgent()	Creates the primary CallAgent responsible for managing the call lifecycle, including making and receiving calls. This command is a foundational element for building the communication flow using Azure Communication Services.
getDeviceManager()	Retrieves the device manager instance which is essential for managing audio and video input devices, such as selecting the proper microphone and camera for the call.

Understanding the Solution for One-Way Audio Issues in ACS and .NET MAUI

The scripts provided above are designed to address a common issue in 1:1 calls using Azure Communication Services (ACS) in a .NET MAUI application, where the audio works one way but not the other. In this case, the callee can hear the caller, but the caller cannot hear the callee. The first part of the solution involves initializing the and setting up proper device permissions to access both the microphone and camera. This is done using the function, which ensures that the app has access to the required devices to handle media streams correctly.

Another crucial part of the script is managing the device selection. The function is used to filter through available audio input devices and select the most appropriate microphone. This ensures that the call is using the correct input, preventing scenarios where the wrong microphone might be selected, which could cause audio issues. The microphone selection is particularly important in mobile environments, where there are often multiple audio input devices available.

Once the devices are properly initialized and selected, the script moves on to handling the actual call setup. The function initiates the 1:1 call, and listeners are set up to handle events such as the addition or removal of remote participants. This is where the event comes into play. By subscribing to changes in the state of remote participants, the script can react to changes such as new participants joining the call or participants leaving. It also tracks the status of remote audio streams to ensure that audio is transmitted correctly between participants.

The handling of audio streams is particularly important for resolving the one-way audio issue. The and functions are used to ensure that the local participant correctly subscribes to the audio streams of remote participants. If a remote participant's audio becomes available, the script processes the stream, ensuring that both parties can hear each other. Proper error handling and stream availability checks ensure that audio is restored if there are temporary disruptions. In this way, the script provides a comprehensive solution to the problem of one-way audio during calls.

// Import necessary modules
const { CallClient, VideoStreamRenderer, LocalVideoStream } = require('@azure/communication-calling');
const { AzureCommunicationTokenCredential } = require('@azure/communication-common');
let callAgent, deviceManager, call;
// Initialize Call Agent with device permissions
async function initializeCallAgent(token) {
   const credential = new AzureCommunicationTokenCredential(token);
   const callClient = new CallClient();
   callAgent = await callClient.createCallAgent(credential);
   deviceManager = await callClient.getDeviceManager();
   await deviceManager.askDevicePermission({ audio: true });
   console.log('CallAgent initialized and permissions granted.');
}
// Start the call and set up event listeners for remote participants
async function startCall(targetUser) {
   const callOptions = { audioOptions: { muted: false } };
   call = callAgent.startCall([targetUser], callOptions);
   setupCallListeners(call);
   console.log('Call initiated.');
}
// Handle remote participants and audio streams
function setupCallListeners(call) {
   call.remoteParticipants.forEach(remoteParticipant => {
      subscribeToRemoteParticipant(remoteParticipant);
   });
   call.on('remoteParticipantsUpdated', e => {
      e.added.forEach(remoteParticipant => subscribeToRemoteParticipant(remoteParticipant));
      e.removed.forEach(() => console.log('Remote participant removed.'));
   });
}
// Subscribe to audio streams from remote participants
function subscribeToRemoteParticipant(remoteParticipant) {
   remoteParticipant.on('audioStreamsUpdated', e => {
      e.added.forEach(audioStream => handleAudioStream(audioStream));
   });
}
// Process remote audio streams
function handleAudioStream(audioStream) {
   if (audioStream.isAvailable) {
      const remoteAudio = audioStream.getMediaStream();
      // Use the remote audio stream
      console.log('Remote audio stream available.');
   } else {
      console.log('Remote audio stream is not available.');
   }
}
// Test Call Agent initialization
initializeCallAgent('YOUR_TOKEN');

// Import ACS libraries in C#
using Azure.Communication.Calling;
using Azure.Communication; 
private CallClient callClient; 
private CallAgent callAgent;
// Initialize Call Agent in .NET MAUI
public async Task InitializeCallAgent(string token) {
   var credential = new CommunicationTokenCredential(token);
   callClient = new CallClient();
   callAgent = await callClient.CreateCallAgentAsync(credential);
   Console.WriteLine("Call Agent initialized.");
}
// Start the call and add remote participant handlers
public async Task StartCall(string targetUserId) {
   var target = new CommunicationUserIdentifier(targetUserId);
   var callOptions = new StartCallOptions();
   var call = await callAgent.StartCallAsync(new[] { target }, callOptions);
   SetupCallHandlers(call);
}
// Handle remote participants and audio streams
private void SetupCallHandlers(Call call) {
   call.OnRemoteParticipantsUpdated += (sender, args) => {
      foreach (var participant in args.AddedParticipants) {
         SubscribeToAudio(participant);
      }
   };
}
// Subscribe to remote audio streams
private void SubscribeToAudio(RemoteParticipant participant) {
   participant.OnAudioStreamsUpdated += (sender, args) => {
      foreach (var stream in args.AddedAudioStreams) {
         if (stream.IsAvailable) {
            var audioStream = stream.GetMediaStream();
            // Play the audio stream
            Console.WriteLine("Audio stream available.");
         }
      }
   };
}
// Call initialization for testing
await InitializeCallAgent("YOUR_TOKEN");

Overcoming Audio Issues in Mobile-to-Mobile 1:1 Calls with Azure Communication Services

One key challenge when dealing with audio issues in mobile-to-mobile 1:1 calls using and is ensuring proper device compatibility. Mobile devices, unlike desktops, can have varied microphone setups, including internal, external, and Bluetooth devices. This diversity can lead to situations where the app selects the wrong microphone, causing the one-way audio problem where one party cannot hear the other. To address this, it's essential to implement device enumeration and dynamic microphone selection using JavaScript to adjust for the best audio input in real-time.

Another often overlooked factor is managing properly across platforms. While permissions may be granted and work well on desktop or browser-based environments, mobile apps have stricter permission handling, especially for accessing hardware like microphones and cameras. In a .NET MAUI app, ensuring that permissions are correctly requested and granted in both the manifest and at runtime is critical. The script should continually monitor the device's permission states, ensuring no interruptions in communication due to ungranted permissions.

Lastly, managing the themselves is vital. Even if the correct microphone is selected and permissions are properly set, handling audio streams dynamically during the call is crucial. Subscribing to audio stream updates using ensures that the app reacts to any changes in the remote participant's audio status, such as muting or audio device switches. This subscription ensures that any temporary disruptions in audio are quickly resolved, helping to prevent one-way audio issues from persisting during a call.

1. What causes one-way audio in mobile-to-mobile 1:1 calls?
2. One-way audio can occur when the application selects the wrong audio input device or if there are incorrect microphone permissions. Using helps in selecting the correct microphone.
3. How can I ensure the right microphone is selected?
4. Implementing dynamic microphone selection through allows the app to choose the best available audio input, minimizing one-way audio problems.
5. Why is there no audio even though permissions are granted?
6. This could be due to platform-specific permission handling. Using ensures that the app has explicit permission to access the microphone on mobile devices.
7. How do I handle remote participant audio streams?
8. You can use and listen for events to handle remote audio streams and ensure the call’s audio is working both ways.
9. Is this issue common across all platforms?
10. One-way audio issues are more common on mobile platforms than desktops due to the variability in audio input devices and more restrictive permission handling on mobile operating systems.

One-way audio issues in mobile-to-mobile calls can be challenging, but with proper device and permission management, they can be resolved. Ensuring that the correct microphone is selected, and permissions are correctly handled is key to solving this problem.

Additionally, subscribing to remote audio streams and handling events like stream availability changes can help maintain smooth communication. Following these strategies will enhance the reliability of 1:1 calls using Azure Communication Services, ensuring consistent two-way audio.