# Manage media and devices (/en/realtime-media/voice/build/control-audio-and-devices/volume-control-and-mute/flutter)

> For AI agents: see the complete documentation index at [llms.txt](/llms.txt).

This page shows you how to configure volume settings for audio recording, audio playback, and for the playback of music files.

## Understand the tech [#understand-the-tech]

Agora Voice SDK supports adjusting the audio volume for both recording and playback to meet practical application use-cases. For example, during a two-person call, you can mute a remote user by adjusting the playback volume setting to 0.

      
  
      
  
      
  
      
  
      
  
      
  
      
    The figure below shows the workflow of adjusting the volume.

    **Volume adjust workflow**

    ![VolumeControlMute](https://assets-docs.agora.io/images/video-sdk/volume-control-mute-adjustVolume.svg)

    **Playback** refers to transmitting an audio signal from a sender to a recipient, where it is played back through a playback device.

    **Recording** refers to the process in which audio signals are captured by a recording device and then sent to the transmitter.

    <CalloutContainer type="warning">
      <CalloutDescription>
        If you set the volume too high using the signal volume adjustment methods, it may lead to audio distortion on some devices.
      </CalloutDescription>
    </CalloutContainer>

    ## Prerequisites [#prerequisites-6]

    Ensure that you have implemented the [SDK quickstart](../index.mdx) in your project.

    ## Implement volume control [#implement-volume-control-6]

    Use one or more of the following volume control methods to adjust volume settings.

    ### Mute and unmute users [#mute-and-unmute-users-5]

    To mute or unmute the local audio stream, call `muteLocalAudioStream`:

    ```dart
    // Stop publishing the local audio stream
    _rtcEngine.muteLocalAudioStream(true);

    // Resume publishing the local audio stream
    _rtcEngine.muteLocalAudioStream(false);
    ```

    To mute or unmute a remote user, call `muteRemoteAudioStream` with the `uid` of the remote user:

    ```dart
    // Stop subscribing to the audio stream of the remote user
    _rtcEngine.muteRemoteAudioStream(remoteUid, true);

    // Resume subscribing to the audio stream of the remote user
    _rtcEngine.muteRemoteAudioStream(remoteUid, false);
    ```

    <CalloutContainer type="info">
      <CalloutDescription>
        To mute remote users without unsubscribing, set their [playback volume](#adjust-the-playback-volume) to `0`.
      </CalloutDescription>
    </CalloutContainer>

    ### Adjust the playback volume [#adjust-the-playback-volume-5]

    Call `adjustPlaybackSignalVolume` or `adjustUserPlaybackSignalVolume` to adjust the volume of the audio playback signal.

    ```dart
    const int volume = 50;
    // Set the local playback volume to 50 for all remote users
    await _rtcEngine.adjustPlaybackSignalVolume(volume);
    // Set the local playback volume for a specific remote user. For example, user with uid 1000
    await _rtcEngine.adjustUserPlaybackSignalVolume(uid: 1000, volume: volume);
    ```

    ### Adjust the recording volume [#adjust-the-recording-volume-5]

    Call `adjustRecordingSignalVolume` to adjust the volume of the audio recording signal.

    ```dart
    // Adjust the recording signal volume to 50
    int vol = 50;
    await _rtcEngine.adjustRecordingSignalVolume(vol);
    ```

    When configuring audio settings, it's essential to understand the default behavior and the options available. Here are the key points to keep in mind:

    * The SDK defaults to a device volume of `85` when using the recording device to capture audio signals.
    * A volume of `0` means mute, and a volume of `255` represents the maximum volume of the device.
    * If the SDK detects that the recording volume is too low in the current environment, it automatically increases the volume of the recording device.
    * The volume of the recording device directly influences the global volume of the device.
    * If the default recording device volume does not meet your requirements, adjust it by regulating the signal amplitude captured by the microphone or sound card.

    ### Get volume information of users [#get-volume-information-of-users-5]

    Voice SDK enables you to obtain the user IDs and corresponding volumes of the three users with the highest instantaneous volumes in a channel during the process of audio recording, mixing, and playback. You use the `onAudioVolumeIndication` callback to obtain this information. A returned `uid` of `0` in the callback indicates the local user.

    <CalloutContainer type="info">
      <CalloutDescription>
        Call `enableAudioVolumeIndication` to enable reporting of the users' volume in the callback.
      </CalloutDescription>
    </CalloutContainer>

    ```dart
    // Retrieve the user IDs of the three users with the highest instantaneous speaking volume,
    // their respective volumes, and determine whether the local user is speaking.
    _rtcEngine.registerEventHandler(RtcEngineEventHandler(
     onAudioVolumeIndication: (RtcConnection connection,
       List<AudioVolumeInfo> speakers, int speakerNumber, int totalVolume) {
      logSink.log(
       '[onAudioVolumeIndication] speakers: ${speakers.toString()}, speakerNumber: $speakerNumber, totalVolume: $totalVolume');
      }
    ));
    ```

    ## Reference [#reference-6]

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

    ### API reference [#api-reference-6]

    * [`adjustRecordingSignalVolume`](https://api-ref.agora.io/en/video-sdk/flutter/6.x/API/class_irtcengine.html#api_irtcengine_adjustrecordingsignalvolume)
    * [`adjustPlaybackSignalVolume`](https://api-ref.agora.io/en/video-sdk/flutter/6.x/API/class_irtcengine.html#api_irtcengine_adjustplaybacksignalvolume)
    * [`adjustUserPlaybackSignalVolume`](https://api-ref.agora.io/en/video-sdk/flutter/6.x/API/class_irtcengine.html#api_irtcengine_adjustuserplaybacksignalvolume)
    * [`adjustAudioMixingPlayoutVolume`](https://api-ref.agora.io/en/video-sdk/flutter/6.x/API/class_irtcengine.html#api_irtcengine_adjustaudiomixingplayoutvolume)
    * [`onAudioVolumeIndication`](https://api-ref.agora.io/en/video-sdk/flutter/6.x/API/class_irtcengineeventhandler.html#callback_irtcengineeventhandler_onaudiovolumeindication)
    * [`muteLocalAudioStream`](https://api-ref.agora.io/en/video-sdk/flutter/6.x/API/class_irtcengine.html#api_irtcengine_mutelocalaudiostream)
    * [`muteRemoteAudioStream`](https://api-ref.agora.io/en/video-sdk/flutter/6.x/API/class_irtcengine.html#api_irtcengine_muteremoteaudiostream)

    ### Sample projects [#sample-projects-5]

    Agora offers the following open-source sample project for adjusting recording, playback, and in-ear monitoring volumes for your reference:

    * GitHub: [join\_channel\_audio.dart](https://github.com/AgoraIO-Extensions/Agora-Flutter-SDK/blob/main/example/lib/examples/basic/join_channel_audio/join_channel_audio.dart)

    For adjusting the playback volume of mixing or audio effect files, refer to the following sample project:

    * GitHub: [audio\_mixing.dart](https://github.com/AgoraIO-Extensions/Agora-Flutter-SDK/blob/main/example/lib/examples/advanced/audio_mixing/audio_mixing.dart)

    ### Frequently asked questions [#frequently-asked-questions-5]

    * [How can I solve the problem of low volume?](/en/api-reference/faq/quality/audio_low)

    ### See also [#see-also-6]

    * [Custom audio source](custom-audio.mdx)
    * [Custom video source](/en/realtime-media/video/build/capture-and-render-video/custom-video)