The following features have been introduced in SDK version 3.5.0 and later:

• Streams are ordered by participant join time.
• There are two categories: Category-A and Category-B.
• Category-A contains only the active speaker's stream.
• Category-B includes all other streams and may also contain the active speaker's stream as a duplicate.
• The number of streams in Category-B can be limited; additional participants are queued.
• Queued participants replace less active streams when they speak.
• When a stream participant leaves, a random queued participant takes their place.
• Use the Active Speaker Method to determine active speakers.
• The ActiveSpeakerChangedEvent is triggered when the active speaker changes.

anchorCommon Use Case

For meetings with more than two participants, multistream can display the active speaker and other attendees simultaneously.

anchorImplement Multistream

Register the onMediaStreamAvailabilityListener callback to manage stream availability:

call.onMediaStreamAvailabilityListener = { available, stream in 
    // if available {
    //     // new stream available
    //} else {
    //     // stream unavailable
    //}
}

1. Render a New Stream

When a new stream becomes available, provide a view for the SDK to render the video:

// MediaStream object returned by callback
let view = MediaRenderView()
stream.renderView = view

2. Implement a Media Stream Information Change Listener

Different MediaStreamChangeEventType values are supported. Events are triggered when related changes occur:

enum MediaStreamChangeEventType {
    case Size
    case Membership
    case Video
    case Audio
}

Register an info change listener to receive updates:

// stream is MediaStream object returned by onMediaStreamAvailabilityListener callback 
stream.setOnMediaStreamInfoChanged { type, info in
    // type: MediaStreamChangeEventType
    // info: MediaStreamChangeEventInfo
}

3. Configure Media Stream for Category-A

Category-A contains a single active speaker stream. Add or update this stream with the specified parameters:

// Duplicate if true; the same active speaker will also be included in Category-B streams.
fun setMediaStreamCategoryA(duplicate: Boolean, quality: MediaStreamQuality)

Define the video quality:

enum MediaStreamQuality {
    case Undefined
    case LD  // 180p
    case SD  // 360p
    case HD  // 720p
    case FHD // 1080p
}

4. Adjust Media Streams for Category-B

Set parameters for all Category-B streams:

• If the number of existing B streams is less than numStreams, additional B streams will be added as necessary.
• If the number of existing B streams is more than numStreams, the extra B streams will be removed.

fun setMediaStreamsCategoryB(numStreams: Int, quality: MediaStreamQuality)

5. Remove Media Stream from Category-A

Remove the active speaker stream from Category-A:

fun removeMediaStreamCategoryA()

After removal, if Category-B exists, all streams have equal priority, and no changes occur based on speaking activity.

6. Remove Media Streams from Category-B

To clear all Category-B streams:

fun removeMediaStreamsCategoryB()

After clearing the Category-B streams, if Category-A remains, only the active speaker's stream is visible.

anchorPin Participant Streams

The pin stream feature ensures a participant's video remains visible regardless of their speaking status or queue position.

Typical Scenario

Multistream pinning allows you to pin a participant's stream while viewing the active speaker and other attendees in a multi-participant meeting.

1. Pin or Update a Pinned Participant Stream

To pin or update a pinned participant stream:

    fun setMediaStreamCategoryC(participantId: String, quality: MediaStreamQuality)

Define the video quality options:

 enum MediaStreamQuality {
     case Undefined
     case LD  // 180p
     case SD  // 360p
     case HD  // 720p
     case FHD // 1080p
 }

2. Remove a Pinned Stream

To unpin a participant's stream:

fun removeMediaStreamCategoryC(participantId: String)

3. Check for Pinning Support

To determine if stream pinning is supported:

var isMediaStreamsPinningSupported : Boolean

4. Listen for Media Stream Changes

To listen for changes in media stream properties, register a change listener to handle events:

 enum MediaStreamChangeEventType {
    case Size
    case Membership
    case Video
    case Audio
    case PinState
}

stream.setOnMediaStreamInfoChanged { type, info in
    // type: MediaStreamChangeEventType
    // info: MediaStreamChangeEventInfo
}