# Migrate from Voice SDK 3.x (/en/realtime-media/voice/reference/migration-guide/unity) > For AI agents: see the complete documentation index at [llms.txt](/llms.txt). Agora SDK v4.0.0 is a new version of the SDK that you can use to embed real-time video and audio into your app. It supports large-scale real-time interactive activities and provides better real-time interactive effects. For details, see [Product overview](../product-overview.md). This page introduces the main steps to upgrade the SDK from v3.x (v3.7.0.3 and earlier) to v4.0.0, as well as the related changes. ## Migration steps [#migration-steps-8] This section introduces the main steps to upgrade the SDK from v3.x to v4.0.0. ### 1. Integrate the SDK [#1-integrate-the-sdk-4] When you have downloaded the Agora v4.0.0 Unity SDK, you see a `.unitypackage` file which can be imported directly into your project in Unity Editor. Once the SDK is successfully integrated, you see an Agora-Video-SDK-Plugin directory in the `Assets` of your project. Refer to the [quickstart](../index.mdx) to integrate the v4.0.0 SDK into your project. ### 2. Update the Agora code in your app [#2-update-the-agora-code-in-your-app-4] The v4.0.0 SDK has optimized or modified the implementation of some functions, resulting in incompatibility with the v3.x SDK. In order to retain Agora functionality in your app, update the code in your app according to [What has changed](#what-has-changed). ## What has changed [#what-has-changed-7] This section is based on v3.x and introduces the main changes of v4.0.0 compared to v3.x in the following categories. You need to update the code of your app according to your business use-case. * Breaking changes: Introduces API compatibility changes. You need to spend significant time modifying the related implementation. * Behavior changes: Introduces changes caused by reasonable optimization of the SDK default behavior and API behavior. Less time is required to modify the related implementation, if any. * Function gaps: Introduces functions that were supported in v3.x but are not supported in v4.0.0. However, these functions are intended to be added in a future release. * Removed APIs: Introduces APIs that were supported in v3.x but removed in v4.0.0. Most of these APIs have alternatives in v4.0.0. Modifying the related implementation should require less time. * Naming and data type changes: Introduces the naming and data type changes of the main APIs. You can update the relevant implementation according to the error message in the IDE, which is expected to take less time. ### Breaking changes [#breaking-changes-6] After upgrading from v3.x to v4.0.0, the way the APIs implement some functions is different. This section introduces compatibility changes for these APIs and the logic for updating the code of your app. #### Multiple channels [#multiple-channels-7] In v3.x, the SDK provides the `AgoraChannel` class and `Channel` delegate to implement multi-channel control. The v3.x SDK supports subscribing to the audio and video streams of multiple channels, but only supports publishing one group of audio and video streams in one channel. v4.0.0 introduces the following changes: * The SDK supports one `IRtcEngine` instance to collect multiple audio and video sources at the same time and publish them to the remote users by setting `IRtcEngineEx` and `ChannelMediaOptions.` * After calling `JoinChannel` to join the first channel, call `JoinChannelEx` multiple times to join multiple channels, and publish the specified stream to different channels through different user ID (`localUid`) and `ChannelMediaOptions` settings. * You can simultaneously publish multiple sets of video streams captured by multiple cameras or screen sharing by setting `publishSecondaryCameraTrack` and `publishSecondaryScreenTrack` in `ChannelMediaOptions`. (Windows) Combined with the multi-channel capability, you can also experience the following functions: * Publish multiple groups of audio and video streams to the remote user through different `localUid`s. * Mix multiple audio streams and publish them to the remote user through one `localUid`. * Mix multiple video streams and publish them to the remote user through one `localUid`. `AgoraChannel` and `IRtcEngine` of v3.x are partially duplicated and overlap in their functionality, so v4.0.0 hides the `IChannel` and `IChannelEventHandler` classes. See the [sample project](https://github.com/AgoraIO-Extensions/Agora-Unity-Video-SDK-QuickStart-NG/tree/release/4.0.0/API-Example-Unity/Assets/API-Example/Examples/Advanced/ScreenShareWhileVideoCall) for more details on how to replace `AgoraChannel` with `JoinChannel` and `ChannelMediaOptions`. The expected migration cost is one day or less. If you need to continue to use the `AgoraChannel` class and `Channel` delegate, contact [support@agora.io](mailto\:support@agora.io). The decision whether to maintain compatibility in a future release is based on your feedback. #### Media stream publishing control [#media-stream-publishing-control-7] In v4.0.0, the SDK gathers more channel-related settings into `ChannelMediaOptions`, including publishing of audio and video streams from different sources, automatic subscribing of audio and video streams, user role switching, token updating, and default dual stream options. You can determine the media stream publishing and subscribing behavior by calling `JoinChannel` or `JoinChannelEx` when joining a channel, or you can flexibly update the media options by calling `UpdateChannelMediaOptions` after joining a channel, such as switching video sources. #### Warning codes [#warning-codes-5] In v3.x, the SDK returns warning codes through the `OnWarning` callbacks. To facilitate locating and troubleshooting issues, v4.0.0 reports problems and causes through the return values of APIs or different callbacks for listening to states. For example: * `OnConnectionStateChanged`: Reports the network connection state. * `OnLocalAudioStateChanged`: Reports the local audio state. * `OnLocalVideoStateChanged`: Reports the local video state. * `OnRemoteAudioStateChanged`: Reports the remote audio state. * `OnRemoteVideoStateChanged`: Reports the remote video state. As a consequence, v4.0.0 removes the `OnWarning` callback. In addition to the breaking changes listed here relative to v3.x, v4.0.0 has a small number of breaking changes relative to the v4.0.0 Beta release. For example: * In v4.0.0, replace `publishAudioTrack` in `ChannelMediaOptions` with `publishMicrophoneTrack`. If you used this feature in v4.0.0 Beta and wish to upgrade to v4.0.0, modify the implementation code of the feature after upgrading the SDK. ### Behavior changes [#behavior-changes-7] This section introduces changes caused by reasonable optimization of the SDK default behavior and API behavior. #### Initialize the IRtcEngine [#initialize-the-irtcengine] In v3.x, you obtain and initialize the `IRtcEngine` through the `GetEngine` (`appId`) or `GetEngine` (`engineConfig`) method. In v4.0.0, you create an `IRtcEngine` instance through `CreateAgoraRtcEngine` or `RtcEngine.Instance`. You initialize the `IRtcEngine` through the `Initialize` method and at the same time, you can also set the channel profile and audio scenario, and config the log files through `RtcEngineContext`. **Register callback events** In v3.x, you can register callback events with C# `delegates`. In v4.0.0, delegates are encapsulated in `Agora.Rtc.RtcEngineEventHandler`. You can also register callback events through the InitEventHandler method: you need to inherited Agora base classes and implement your own `EventHandler` class, and register an `EventHandler` instance through the `InitEventHandler`. **Release resources** If you need to release all the resources used by the Agora Unity SDK: In v3.x, you need to call the `Destroy` method. In v4.0.0, you need to call the `Dispose` method. #### Channel profile [#channel-profile-7] In v3.x, the default channel profile is `CHANNEL_PROFILE_COMMUNICATION` (the communication profile). Because the interactive streaming profile supports seamless switching from one-to-one calls to multi-user interaction, since v3.0.0, Agora has changed the internal transmission protocol and the ability to resist poor network conditions in the communication profile to be consistent with the interactive streaming profile. In v4.0.0, Agora also changed the default channel profile to `CHANNEL_PROFILE_LIVE_BROADCASTING` (the interactive streaming profile). #### Default log file [#default-log-file-7] In v3.x, when the SDK creates multiple log files, the earlier files are named in a `agorasdk_x.log` format, such as `agorasdk_1.log`. v4.0.0 modified the naming format to `agorasdk.x.log`, such as `agorasdk.1.log`. Additionally, v4.0.0 adds the `agoraapi.log` file to record API logs. #### Fast channel switching [#fast-channel-switching-7] In v3.x, you need to call `SwitchChannel` to quickly switch a channel. In v4.0.0, you can achieve the same switching speed as `SwitchChannel` in v3.x by switching a channel through `LeaveChannel` and `JoinChannel`. Therefore, v4.0.0 removes `SwitchChannel`. If you call `SwitchChannel` to quickly switch a channel in v3.x, you need to call `LeaveChannel` to leave the current channel in v4.0.0 and `JoinChannel` to join the second channel instead. #### Media options [#media-options-6] There are differences in the behavior of the SDK when setting channel media options while joining a channel between v3.7.0 and v4.0.0: * In v3.7.0, if you set `publishLocalAudio` in `ChannelMediaOptions` to `false`, it will stop publishing the local audio stream within the channel. * In v4.0.0, if you set `publishMicrophoneTrack` in `ChannelMediaOptions` to `false`, it will not only stop publishing the local audio stream within the channel but also stop local microphone capture. #### Video information change event (iOS) [#video-information-change-event-ios-2] If the video capture device is adjusted to landscape or portrait mode during video capture, in v3.7.0 and v4.0.0, the following differences exist in the video information change events reported by the SDK: * In v3.7.0, the `rotation` parameter in the `OnVideoSizeChanged` callback displays the current device rotation information. * In v4.0.0, the `rotation` parameter in the `OnVideoSizeChanged` callback is always `0`. **Agora self-developed extensions** v4.0.0 adds the feature of automatically loading self-developed dynamic libraries based on v4.0.0 Beta. As of this release, when using an Agora self-developed extension, you do not need to manually integrate the dynamic library in the project. The SDK automatically loads the dynamic library during the initialization phase of `IRtcEngine`. You can directly call the corresponding method of the extension to enable this feature. | API | Extension type | | :----------------------------------------------------------------------------------------------------------------- | :--------------------------- | | `EnableVirtualBackground` | Virtual background extension | | * `SetBeautyEffectOptions` * `SetVideoDenoiserOptions` * `SetLowlightEnhanceOptions` * `SetColorEnhanceOptions` | Video enhancement extension | | `EnableRemoteSuperResolution` | Super resolution extension | | - `SetAudioEffectPreset` - `SetVoiceBeautifierPreset` - `SetVoiceConversionPreset` | Voice beautifier extension | | `EnableSpatialAudio` | Spatial audio extensionE | | `EnableContentInspect` | Content moderation extension | **Virtual metronome** When you call `StartRhythmPlayer`, the SDK publishes the sound of the virtual metronome to the remote by default. If you do not want the remote users to hear the virtual metronome, refer to the following operations: In v3.x, call the `ConfigRhythmPlayer,` and set `publish` to `false`. In v4.0.0, set `publishRhythmPlayerTrack` in `ChannelMediaOptions` to `false`. **Volume indication** You can call the `EnableAudioVolumeIndication` method to enable the user's volume indication function. There is a difference in the definition of the `interval` parameter in the `EnableAudioVolumeIndication` method between v3.x and v4.0.0, as follows: In v3.x, Agora recommends that you set the `interval` to be greater than 200 ms. The minimum is 10 ms; otherwise, the `OnAudioVolumeIndication` callback is not received. In v4.0.0, you must set the `interval `to an integer that is a multiple of 200 ms. If the value of `interval` is lower than 200, the SDK automatically adjusts it to 200. When the user's volume indication is enabled, the SDK triggers the `OnAudioVolumeIndication` callback at the time interval set in this method. If the local user calls `MuteLocalAudioStream` to mute themselves, the SDK behaves inconsistently between v3.x and v4.0.0: In v3.x, the SDK immediately stops reporting the local user's volume indication callback. In v4.0.0, the SDK continues to report the local user's volume indication callback. **Device permissions** In v3.x, `LOCAL_AUDIO_STREAM_ERROR_DEVICE_NO_PERMISSION` in `OnLocalAudioStateChanged` reports that there is no permission to start the capture device, and `LOCAL_VIDEO_STREAM_ERROR_DEVICE_NO_PERMISSION` in `OnLocalVideoStateChanged` reports that there is no permission to start the video capture device. In v4.0.0, the permission statuses of the audio and video capture devices are both reported in the `OnPermissionError` callback. **Pre-call network test** If you need to start or stop the network connection quality test, note the following: In v3.x, you can call `EnableLastmileTest` to start the network quality test. If you want to stop the network test, you need to call `DisableLastmileTest`. In v4.0.0, you can call `StartLastmileProbeTest` to enable network quality testing. If you want to stop network testing, you need to call `StopLastmileProbeTest`. **Raw audio and video data** In v3.x, you can manage raw audio and video data through the APIs in `AudioRawDataManager` and `VideoRawDataManager` respectively. In v4.0.0, you call the `RegisterAudioFrameObserver` or `RegisterVideoFrameObserver` in the `IRtcEngine` class to register an audio or video frame observer and monitor the audio or video data, or you can also inherit the `IRtcEngine` class to implement data monitoring. **Remote media event triggering mechanism** In the following use-cases, the mechanism of triggering remote media events is changed: * Use-case 1: When the host calls `MuteLocalAudioStream` or `MuteLocalVideoStream` outside the channel to change the publishing status of the local audio or video stream and then joins the channel. * Use-case 2: When the host calls `MuteLocalAudioStream` or `MuteLocalVideoStream` within the channel to change the publishing status of the local audio or video stream, and then other users join the channel. The behavior differences of Agora SDK between v3.7.0 and v4.0.0 are listed as follow: * In v3.7.0, the local user receives the `OnRemoteAudioStateChanged` or `OnRemoteVideoStateChanged` callback, which reports the status changes of the remote host's audio or video streams. * In v4.0.0, instead of the `OnRemoteAudioStateChanged` or `OnRemoteVideoStateChanged` callback, the local user receives the `OnUserMuteAudio` or `OnUserMuteVideo` callback, which reports the changes in the remote host's publishing status. ### Function gaps [#function-gaps-7] This section introduces functions that were supported in v3.x but are no longer supported or behave inconsistently in v4.0.0. Plans exist to support them or make them consistent in a future release, however. #### Audio application scenarios [#audio-application-scenarios-6] v4.0.0 reconstructs the audio application scenarios, which can replace most of the audio application scenarios of v3.x. The following table shows the correspondence of audio application scenarios in the two releases: | v3.x | v4.0.0 | | :-------------------------------------- | :------------------------------------------------------------------ | | `AUDIO_SCENARIO_DEFAULT` | `AUDIO_SCENARIO_DEFAULT` | | `AUDIO_SCENARIO_CHATROOM_ENTERTAINMENT` | `AUDIO_SCENARIO_CHATROOM` | | `AUDIO_SCENARIO_EDUCATION` | `AUDIO_SCENARIO_DEFAULT` | | `AUDIO_SCENARIO_GAME_STREAMING` | `AUDIO_SCENARIO_GAME_STREAMING` or `AUDIO_SCENARIO_HIGH_DEFINITION` | | `AUDIO_SCENARIO_SHOWROOM` | `AUDIO_SCENARIO_DEFAULT` | | `AUDIO_SCENARIO_CHATROOM_GAMING` | `AUDIO_SCENARIO_CHATROOM` | | `AUDIO_SCENARIO_IOT` | `AUDIO_SCENARIO_DEFAULT` | | `AUDIO_SCENARIO_MEETING` | `AUDIO_SCENARIO_MEETING` | #### Unsupported functions [#unsupported-functions-6] Compared to v3.x, some features are not supported or only partially supported in v4.0.0. This section shows the APIs currently unsupported but for which support is planned in a future release. Remote video stream fallback: * `SetRemoteUserPriority` Screen sharing: * `OnScreenCaptureInfoUpdated` ### Removed APIs [#removed-apis-7] The v4.0.0 removes deprecated or unrecommended APIs. Alternatives to the removed API or reasons for their removal are shown as follows: * `VideoRawDataManager`: Use the APIs in the `IVideoFrameObserver` class instead. * `AudioRawDataManager`: Use the APIs in the `IAudioFrameObserver` class instead. * `PacketObserver`: Rarely used in v3.x. * `EnableFilpTextureApply`: Agora recommends you implementing this function by yourself. * `SetGameFps`: Agora recommends you implementing this function by yourself. * `VirtualBackgroundSourceEnabled`: Use the return value of `EnableVirtualBackground` instead. * `OnUserSuperResolutionEnabled`: Use the `OnRemoteVideoStats` member of the `superResolutionType` class instead. * `SetAudioMixingPlaybackSpeed`: Use the relevant API under the `IMediaPlayer` class instead. * `SetExternalAudioSourceVolume`: Use `AdjustCustomAudioPublishVolume` instead. * `GetAudioFileInfo` and `OnRequestAudioFileInfo`: Use `GetDuration` instead. * `OnAudioDeviceTestVolumeIndication`：Use `OnAudioVolumeIndication` instead. * `SetLocalPublishFallbackOption` and `OnLocalPublishFallbackToAudioOnly`: Rarely used in v3.x. * `RENDER_MODE_FILL(4)` in `RENDER_MODE_TYPE`: This mode can cause image overstretch and is not recommended. * The following enumerations in `AUDIO_MIXING_REASON_TYPE`: Rarely used in v3.x. * `AUDIO_MIXING_REASON_STARTED_BY_USER` * `AUDIO_MIXING_REASON_START_NEW_LOOP` * `AUDIO_MIXING_REASON_PAUSED_BY_USER` * `AUDIO_MIXING_REASON_RESUMED_BY_USER` * `OnAudioMixingFinished`: Use `OnAudioMixingStateChanged` instead. * `EnableDeepLearningDenoise`: The SDK adds deep-learning noise reduction as one of its capability in a future release instead of implementing through an API. * The `channel` parameter in `TakeSnapshot` and `OnSnapshotTaken`: The parameter is redundant. * `SetDefaultMuteAllRemoteVideoStreams`: Use`autoSubscribeVideo` in the `ChannelMediaOptions` instead. * `SetDefaultMuteAllRemoteAudioStreams`：Use `autoSubscribeAudio` in the `ChannelMediaOptions` instead. * `LOCAL_VIDEO_STREAM_ERROR_SCREEN_CAPTURE_WINDOW_NOT_SUPPORTED` in `LOCAL_VIDEO_STREAM_ERROR`：Deprecated in v3.x. * The `replace` parameter in `StartAudioMixing`: Use `publishMicrophoneTrack` in the `ChannelMediaOptions` instead. ### Naming changes [#naming-changes-7] The naming changes in v4.0.0 cause error messages in the IDE when you compile your project, and you need to update the code of your app according to each error message. **Namespace** * `namespace agora_gaming_rtc` is renamed as `namespace Agora.Rtc` **Classes** * `AudioPlaybackDeviceManager` and `AudioRecordingDeviceManager` are both included in `IAudioDeviceManager` * `VideoDeviceManager` is changed to `IVideoDeviceManager` * `MediaRecorder` is changed to `IMediaRecorder` * `MetadataObserver` is changed to `IMetadataObserver` * `AgoraCallback` is changed to `IRtcEngineEventHandler` **APIs and parameters** * `AdjustLoopbackRecordingSignalVolume` is changed to `AdjustLoopbackSignalVolume`. * `OnFirstLocalAudioFrame` is changed to `OnFirstLocalAudioFramePublished`. * The `fileSize` member in `LogConfig` is renamed to `fileSizeInKB`. * The `options` parameter in `JoinChannel[2/2]` is changed to `mediaOptions`. * The `report_vad` parameter in `enableAudioVolumeIndication` is changed to `reportVad`.