Optimize Video Track - iOS

While optimizing for the best viewing experience, it is necessary to fine-tune the video tracks that are being used during the calls.

For the best fine-tuning experience, we have introduced the ability to pass a custom video track for the participant's media before and during the meeting.

Custom Video Track

This feature gives you powerful tools to deliver the best possible video stream for varying network conditions. You can specify a modern video quality profile (bitrateMode) and control simulcast behavior (maxLayer).

From version 3.1.0 onward, once you set a custom video track created using createCameraVideoTrack(), VideoSDK remembers its settings and automatically reuses them whenever the webcam is turned back on. To change the track configuration, call disableWebcam(), then pass a new track created using createCameraVideoTrack() to enableWebcam(customVideoStream:). VideoSDK preserves only tracks created using createCameraVideoTrack(). Filters applied through external SDKs or packages for virtual background are not preserved and must be re-applied each time the webcam is re-enabled.

How to Create a Custom Video Track ?

• You can create a Video Track using createCameraVideoTrack() method of VideoSDK class.

• This method can be used to create video track by specifying parameters like video resolution, camera facing mode, and the quality controls (bitrateMode and maxLayer).

• You can choose video resolution from the below mentioned list of values for the encoder config:

Config	Resolution	Frame Rate	Optimized (kbps)	Balanced (kbps)	High Quality (kbps)
h90p_w160p	160x90	30 fps	40	90	120
h180p_w320p	320x180	30 fps	60	120	180
h360p_w640p	640x360	30 fps	300	450	600
h540p_w960p	960x540	30 fps	600	900	1200
h720p_w1280p	1280x720	30 fps	1000	1500	2000
h1080p_w1920p	1920x1080	30 fps	1500	2200	2700
h120p_w160p	160x120	30 fps	40	90	120
h180p_w240p	240x180	30 fps	90	120	180
h240p_w320p	320x240	30 fps	100	150	200
h360p_w480p	480x360	30 fps	270	360	540
h480p_w640p	640x480	30 fps	350	600	900
h720p_w960p	960x720	30 fps	900	1200	1600
h1080p_w1440p	1440x1080	30 fps	1500	2000	2700

note

Above mentioned encoder configurations are valid for both, landscape as well as portrait mode.

Example

Swift

import WebRTC
guard let videoMediaTrack = try? VideoSDK.createCameraVideoTrack(
  // This will accept the enum value of CustomVideoTrackConfig which contains resolution (height x width) of video you want to capture.
  encoderConfig: .h720p_w960p, // .h360p_w640p | .h480p_w640p ... // Default : .h720p_w1280p

  // It will specify whether to use front or back camera for the video track.
  facingMode: .front, // .back,  Default : .front

  // We will discuss this parameter in next step.
  multiStream: true, // false,  Default : true

  // Optional: This specifies the video codec used to encode this track.
  codec: .VP8, // .H264 | .VP9 | .AV1 , Default : .VP8

  // Optional: This controls the video quality and bandwidth usage.
  bitrateMode: BitrateMode.HIGH_QUALITY, // .BANDWIDTH_OPTIMIZED | .BALANCED Default: .BALANCED 

  // Optional: This specifies the maximum number of simulcast layers (maxLayer) to publish.
  maxLayer: EncodingLayer.MAX_LAYER_2 // 2 |  Default: .MAX_LAYER_3

) else { return}

caution

The capabilities of the device have a significant impact on how custom track configurations behave. Assuming a case where you set encoder configuration to 1080p but the webcam only supports 720p, then encoder configuration will automatically switch to the highest resolution that the device can handle, which is 720p.

What is multiStream?

• This parameter specifies whether the stream should send multiple resolution layers or a single resolution layer. It is true by default.

Refer to the Simulcast (Adaptive Bitrate) guide for the layers a track publishes and for how participants select the layer they receive.

What is BitrateMode?

BitrateMode is the key setting for video quality. It lets you decide whether to prioritize sharp details, save internet data, or find a good balance between the two.

You can choose from three distinct modes:

• .BANDWIDTH_OPTIMIZED: Prioritizes lower bandwidth usage over video quality. Ideal for users with poor or unstable network conditions.
• .BALANCED: The default setting. It provides a smart compromise between clear video and efficient bandwidth consumption, suitable for most use cases.
• .HIGH_QUALITY: Prioritizes video quality over bandwidth usage. Use this when high-fidelity video is essential and viewers are expected to have strong network connections.

What is MaxLayer?

• This parameter caps how many layers a track publishes, and accepts EncodingLayer.MAX_LAYER_2 or EncodingLayer.MAX_LAYER_3. It applies only when multiStream is true, and defaults to .MAX_LAYER_3.

Refer to the Simulcast (Adaptive Bitrate) guide for what each value publishes.

What is codec?

• This parameter specifies the video codec used to encode your stream. VideoSDK supports VP8 (default), H264, VP9, and AV1, set through VideoCodec.
• Currently, VideoSDK doesn't support multiStream for H264, VP9, and AV1. multiStream defaults to true, so set multiStream: false when you create an H264, VP9, or AV1 track. Otherwise VideoSDK sets it to false for you and emits the ERROR_MULTISTREAM_NOT_SUPPORTED error.

Refer to the Video Codecs guide to compare the four codecs, to check which codec a meeting is actually using, and to handle the cases where a codec is not supported.

How to Setup a Custom Video Track ?

The custom track can be set up both before and after the initialization of the meeting.

1. Setting up a Custom Track during the initialization of a meeting
2. Setting up a Custom Track with methods

1. Setting up a Custom Track during the initialization of a meeting

If you are passing webcamEnabled: true in the createRoom and want to use custom tracks from start of the meeting, you can pass custom track in the customCameraVideoTrack as shown below.

caution

• Custom Track will not apply on webcamEnabled: false configuration.

• Custom video track's facingMode takes precedence over the cameraPosition specified during the join method. Ensure you set facingMode appropriately to achieve the desired camera orientation.

Example

Swift

import VideoSDKRTC

guard let videoMediaTrack = try? VideoSDK.createCameraVideoTrack(
    encoderConfig: .h720p_w960p,
    facingMode: .front,
    multiStream: true,
    codec: .VP8, // .H264 | .VP9 | .AV1 , Default : .VP8
    bitrateMode: .HIGH_QUALITY, // Default: .BALANCED
    maxLayer: .MAX_LAYER_2 // Default: .MAX_LAYER_3
) else {
    return
}

let meeting = VideoSDK.initMeeting(
    meetingId: meetingId,
    participantName: name,
    micEnabled: micEnabled, // optional, default: true
    webcamEnabled: cameraEnabled, // optional, default: true
    // Pass the custom track here which will be used to when webcam is auto started
    customCameraVideoStream: videoMediaTrack
)

2. Setting up a Custom Track with methods

In order to switch tracks during the meeting, you have to pass the CustomTrack in the enableWebCam() method of Room.

tip

Make sure to call disableWebcam() before you create a new track as it may lead to unexpected behavior.

Example

Swift

import VideoSDKRTC

@IBAction func videoButtonTapped(_ sender: Any) {
    if !on {
        guard let videoMediaTrack = try? VideoSDK.createCameraVideoTrack(
            encoderConfig: .h720p_w960p,
            facingMode: .front,
            multiStream: true,
            codec: .VP8, // .H264 | .VP9 | .AV1 , Default : .VP8
            bitrateMode: .HIGH_QUALITY, // Default: .BALANCED
            maxLayer: .MAX_LAYER_2 // Default: .MAX_LAYER_3
        ) else {
            return
        }
        self.meeting?.enableWebcam(customVideoStream: videoMediaTrack)
    } else {
        self.meeting?.disableWebcam()
    }
}

Which Configuration is suitable for Device ?

In this section, we will understand participant size wise encoder(Resolution) and multiStream configuration.

API Reference

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

• createCameraVideoTrack()