Optimize Audio Track - iOS

While optimizing for the best listening experience, it is necessary to fine-tune the audio track that is being used during the calls.

You can pass a custom audio track for the participant's media before joining the room and while in it.

Custom Audio Track

This feature can be used to create a custom Audio track for the Audio of the participants with different encoder configuration and send it to other participants.

Once you set a custom audio track created using createMicrophoneAudioTrack(), the SDK remembers its settings and automatically reuses them whenever the mic is turned back on. To change the track configuration, pass a new track created the same way to changeMic(customMicrophoneTrack:). The SDK preserves only tracks created with this method.

Encoder Config Reference

Encoder Config	Bitrate	Auto Gain	Echo Cancellation	Noise Suppression
speech_low_quality	24 kbps	TRUE	TRUE	TRUE
speech_standard	24 kbps	TRUE	TRUE	TRUE
music_standard	40 kbps	FALSE	FALSE	FALSE
standard_stereo	64 kbps	FALSE	FALSE	FALSE
high_quality	128 kbps	FALSE	FALSE	FALSE
high_quality_stereo	192 kbps	FALSE	FALSE	FALSE

Note: If you face issues related to echo, you can use noiseConfig with echoCancellation: true. Echo cancellation attempts to prevent echo effects on a two-way audio connection by reducing or eliminating crosstalk between the user's output device and their input device — for example, filtering out sound produced by the speakers from being captured by the microphone input track.

How to Create Custom Audio Track ?

• You can create an audio track using createMicrophoneAudioTrack() method of VideoSDK class.

• This method can be used to create audio track using different noise configurations. Every NoiseConfig flag is optional: noiseSuppression, echoCancellation and autoGainControl default to true, and highPassFilter defaults to false.

• The method is async throws, so call it with try await. It returns a CustomStreamTrack.

• To capture from a specific microphone, pass its deviceId from VideoSDK.getMics() as microphoneId.

• The microphone opens when the track is created, but the method never asks for microphone permission. Ask for permission first, and create the track after access is granted. Until then, the method throws ERROR_MICROPHONE_ACCESS_DENIED_OR_DISMISSED.

• The method waits up to 2 seconds for the microphone to open, and throws the errors that happen in that time, such as ERROR_MICROPHONE_IN_USE. If the microphone fails after that, the track ends and its onEnded handler receives the error.

• If you create a track and don't use it, call stop() on it to release the microphone.

Example

Swift

do {
    let audioMediaTrack = try await VideoSDK.createMicrophoneAudioTrack(
        encoderConfig: .speech_standard, // Default : .speech_standard
        microphoneId: nil, // A deviceId from VideoSDK.getMics(). Default : nil
        noiseConfig: NoiseConfig(
            // It is used to improve the quality of audio by removing background noise
            // that can interfere with the clarity of speech.
            noiseSuppression: true,

            // It is used to remove unwanted echoes from voice.
            echoCancellation: true,

            // It is used to maintain a consistent level of loudness or amplitude in a voice.
            autoGainControl: true,

            // It removes low frequency sounds hence making the audio clearer.
            highPassFilter: true
        )
    )
    // Pass audioMediaTrack to createRoom() or changeMic(customMicrophoneTrack:)
} catch {
    print("Failed to create the audio track: \(error)")
}

How to Setup Custom Audio Track ?

The custom track can be set up both when you create the room and after you join it.

1. Setting up a Custom Track when you create the room
2. Setting up a Custom Track with methods

1. Setting up a Custom Track when you create the room

If you are passing micEnabled: true to VideoSDK.createRoom and want to use custom tracks from the moment you join the room, you can pass custom track as customMicrophoneTrack to createRoom as shown below.

caution

With micEnabled: false, the mic stays off when you join, so the custom track is not sent. When you turn the mic on later with unmuteMic(), the SDK uses the settings of this track.

Example

Swift

do {
    let customMicrophoneTrack = try await VideoSDK.createMicrophoneAudioTrack(
        noiseConfig: NoiseConfig(
            noiseSuppression: true,
            echoCancellation: true,
            autoGainControl: true,
            highPassFilter: true
        )
    )

    let room = try VideoSDK.createRoom(
        roomId: roomId,
        token: token,
        participantName: name,
        micEnabled: true, // when passed true, it creates an audio track with defined configs
        camEnabled: cameraEnabled, // optional, default: true

        // Pass the custom audio track here which will be used when the mic is auto started
        customMicrophoneTrack: customMicrophoneTrack
    )
} catch {
    print("Failed to set up the room: \(error)")
}

2. Setting up a Custom Track with methods

In order to switch tracks while in the room, you have to pass the new track to the changeMic(customMicrophoneTrack:) method of Room. If the mic is on, the SDK turns it off and on again with the new track, so the new noise settings apply at once. If the mic is off, it turns on with the new track.

You can also pass a track to unmuteMic(customMicrophoneTrack:) when you turn the mic on. Both methods are async throws, so call them with try await inside a Task.

Example

Swift

@IBAction func changeAudioTrackTapped(_ sender: Any) {
  Task {
    do {
      let audioMediaTrack = try await VideoSDK.createMicrophoneAudioTrack(
        noiseConfig: NoiseConfig(
            noiseSuppression: true,
            echoCancellation: true,
            autoGainControl: true,
            highPassFilter: true
        )
      )

      try await self.room?.changeMic(customMicrophoneTrack: audioMediaTrack)
    } catch {
      print("Failed to change the audio track: \(error)")
    }
  }
}

API Reference

The API references for all the methods and events utilised in this guide are provided below.

• createMicrophoneAudioTrack()
• changeMic()
• unmuteMic()