POST/rooms/:name/live-streaming/start
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Multiple RTMP URLs can be passed using the endpoints property, which accepts an array of RTMP URLs. (See addLiveStreamingEndpoints() for a code example using this property.)
Cannot accept both rtmpURL and endpoints at the same time. Use endpoints when you want to start both RTMP and HLS.
Multiple streaming sessions (up to max_streaming_instances_per_room on your Daily domain) can be started by specifying a unique instanceId. Each instance can have a different layout, participants, lifetime, and update rules.
Contact us to configure max_streaming_instances_per_room for your domain.
Note: recording and streaming instances that share the same instanceId also share the same underlying composition process, so any layout change made to streaming will also affect recording, and vice-versa.
A 503 status code may be returned if there are not enough workers available. In this case, you may retry the request again.
If you would like to use both RTMP and HLS, we recommend that you define streaming_endpoints for both types of endpoints.
Note: The outgoing RTMP stream has the following properties:
- Resolution: 1920 x 1080
- Frame rate: 30fps
- Keyframe: every 2 seconds (60 frames)
- Target bitrate: 5Mbps
Path params
The name of the room.
Body params
Property that specifies the output width of the given stream.
Property that specifies the output height of the given stream.
Property that specifies the video frame rate per second.
Property that specifies the video bitrate for the output video in kilobits per second (kbps).
Property that specifies the audio bitrate for the output audio in kilobits per second (kbps).
Amount of time in seconds to wait before ending a recording or live stream when the room is idle (e.g. when all users have muted video and audio). Default: 300 (seconds). Note: Once the timeout has been reached, it typically takes an additional 1-3 minutes for the recording or live stream to be shut down.
Maximum duration in seconds after which recording/streaming is forcefully stopped. Default: `15000` seconds (3 hours). This is a preventive circuit breaker to prevent billing surprises in case a user starts recording/streaming and leaves the room.
Specifies the background color of the stream, formatted as #rrggbb or #aarrggbb string.
UUID for a streaming or recording session. Used when multiple streaming or recording sessions are running for single room.
An object specifying the way participants’ videos are laid out in the live stream. See given layout configs for description of fields. Preset must be defined.
Default Layout
Single Participant Layout
Active Participant Layout
Portrait Layout
Custom Layout
Custom video layouts with VCS baseline composition
Daily offers a "baseline" composition option via the "custom" layout preset for customizing your video layouts while live streaming. This option allows for even more flexibility while using Daily's live streaming API.
Many VCS properties use a "grid unit". The grid unit is a designer-friendly, device-independent unit. The default grid size is 1/36 of the output's minimum dimension. In other words, 1gu = 20px on a 720p stream and 30px on a 1080p stream. Learn more about grid units in our [VCS SDK docs](/reference/vcs/layout-api#the-grid-unit).
composition_params
Sets the layout mode. Valid options:
- single: Show a single full-screen video.
- split: Show the first two participants side-by-side.
- grid: Show up to 20 videos in a grid layout.
- dominant: Show the active speaker in a large pane on the left, with additional video thumbnails on the right.
- pip: Show the active speaker in a full-screen view, with the first participant inlaid in a corner.
Sets whether a text overlay is displayed. You can configure the contents of the overlay with the text.* properties.
Sets whether an image overlay is displayed. You can configure the display of the overlay with the image.* properties. The image used must be passed in the session_id layout option when the stream or recording is started.
Sets whether a banner overlay is displayed. The banner can be used for TV-style "lower third" graphics, or displayed in any corner. You can configure the content of the overlay with the banner.* properties.
Sets whether a WebFrame overlay is displayed. You can configure the display of this live web browser overlay with the webFrame.* properties. The URL and the browser viewport size can be changed while your stream or recording is running.
Sets whether a sidebar is displayed. You can configure the display of the sidebar with the sidebar.* properties.
Sets whether a title screen (a "slate") is displayed. You can configure the display of the slate with the titleSlate.* properties.
Sets whether a title screen (a "slate") is automatically shown at the start of the stream. You can configure the display of this automatic slate with the openingSlate. properties.
Group: videoSettings
Limits the number of non-screenshare streams that are included in the output.
Lets you do render-time reordering of video inputs according to participant IDs within a Daily room. To enable this sorting, pass a comma-separated list of participant IDs as the value for this param; video inputs matching these IDs will be moved to the top of the list. If you pass an ID that is not present in the room, it's ignored. All other video inputs will remain in their original order. The default value is an empty string indicating no reordering. Also note that videoSettings.preferScreenshare takes precedence over the ordering passed here. For more information about how participants and videos are sorted, see the section on selecting participants.
When enabled, screen share inputs will be sorted before camera inputs. This is useful when prioritizing screen shares in your layout, especially when all inputs are not included in the final stream. For more information about how participants and videos are sorted, see the section on selecting participants.
When enabled, paused video inputs will not be included. By default this is off, and paused inputs are displayed with a placeholder graphic. ("Paused video" means that the video track for a participant is not available, either due to user action or network conditions.)
When enabled, audio-only inputs will not be included in rendering. By default this is off, and audio participants are displayed with a placeholder graphic.
When enabled, any screenshare video inputs beyond the first one will not be included in rendering. You can control the ordering of the inputs using the layout.participants property to explicitly select which participant should be first in the list of inputs.
Sets whether call participants' names are displayed on their video tiles.
Sets whether to display video tiles with squared or rounded corners. Note that some modes (dominant and pip) have additional params to control whether the main video has rounded corners or not.
Sets the corner radius applied to video layers when videoSettings.roundedCorners is enabled, in grid units.
Controls how source video is displayed inside a tile if they have different aspect ratios. Use 'fill' to crop the video to fill the entire tile. Use 'fit' to make sure the entire video fits inside the tile, adding letterboxes or pillarboxes as necessary.
Controls how a screenshare video is displayed inside a tile if they have different aspect ratios. Use 'fill' to crop the video to fill the entire tile. Use 'fit' to make sure the entire video fits inside the tile, adding letterboxes or pillarboxes as necessary.
Sets the background color for video placeholder tile. Valid options:
-
Hex color codes
-
RGB or RGBA syntax
-
Standard CSS color names (e.g. 'blue')
Sets the highlight color. It's used as the border color to indicate the 'dominant' video input (typically the active speaker). Valid options:
-
Hex color codes
-
RGB or RGBA syntax
-
Standard CSS color names (e.g. 'blue')
Sets the stroke width used to render a highlight border. See also 'videoSettings.highlight.color'. Specified in grid units.
Sets the visual margin between the two video layers shown in split mode, in grid units.
Selects whether the 'split' layout mode is rendered in a horizontal or vertical configuration. The default value 'auto-by-viewport' means that the split direction will be automatically selected to be most appropriate for the current viewport size: if the viewport is landscape or square, the split axis is vertical; if portrait, the split axis is horizontal. Valid options: 'auto-by-viewport', 'vertical', 'horizontal'
When enabled, the layout will automatically switch to dominant mode from grid if a screenshare video input is available. By using this automatic behavior, you avoid having to manually switch the mode via an API call.
Overrides the visual margin between items in grid mode, in grid units. The default value of -1 means that the layout algorithm selects a reasonable margin automatically depending on the number of videos.
Overrides the outer padding around items in grid mode, in grid units. The default value of -1 means that the layout algorithm selects a reasonable padding automatically depending on the number of videos.
By default, the grid mode will highlight the dominant video (typically the "active speaker") with a light outline. You can disable the highlight using this setting.
By default, the layout for the grid mode will try to preserve the aspect ratio of the input videos, i.e. avoid cropping the videos and instead add margins around the grid if needed. Setting this parameter to false will make the grid layout fill all available area, potentially cropping the videos.
Control where the dominant (or "active speaker") video is displayed in the dominant layout mode. Values are left, right, top or bottom.
Sets the position of the imaginary line separating the dominant video from the smaller tiles when using the dominant layout. Values are from 0 to 1. The default is 0.8, so if videoSettings.dominant.position is set to left, the dominant video will take 80% of the width of the screen on the left.
Controls how many "chiclets", or smaller video tiles, appear alongside the dominant video when using the dominant layout.
When in dominant mode, the large tile displays the active speaker by default. Turn off this followDomFlag to display the first participant instead of the active speaker.
Margin between the “chiclet” items, in grid units.
Padding around the row/column of “chiclet” items, in grid units.
Margin between the "dominant" video and the row/column of "chiclet" items, in grid units.
Sets whether the "dominant" video will be rendered with rounded corners when videoSettings.roundedCorners is enabled. Defaults to false because sharp corners are a more natural choice for the default configuration where the dominant video is tightly aligned to viewport edges.
Sets the position of the smaller video in the pip (picture-in-picture) layout. Valid options: 'top-left', 'top-right', 'bottom-left', 'bottom-right'.
Sets the aspect ratio of the smaller video in the pip layout. The default is 1.0, which produces a square video.
Sets the height of the smaller video in the pip layout, measured in grid units.
Sets the margin between the smaller video and the edge of the frame in the pip layout, in grid units.
When in "pip" (or picture-in-picture) mode, the overlay tile displays the first participant in the participant array by default. Turn on this followDomFlag to display the active speaker instead.
Sets whether the main video in pip mode will be rendered with rounded corners when videoSettings.roundedCorners is enabled. Defaults to false because sharp corners are a more natural choice for the default configuration where the main video is full-screen (no margin to viewport edges).
Sets the participant label style option: font family. Valid options: DMSans, Roboto, RobotoCondensed, Bitter, Exo, Magra, SuezOne, Teko
Sets the participant label text font weight. Valid options: 100, 200, 300, 400, 500, 600, 700, 800, 900.
Note: Not all font weights are valid for every font family.
Sets the offset value for participant labels on the x-axis, measured in grid units.
Sets the offset value for participant labels on the y-axis, measured in grid units.
Sets the participant label font color. Valid options:
-
Hex color codes
-
RGB or RGBA syntax
-
Standard CSS color names (e.g. 'blue')
Sets the label font stroke color (the line outlining the text letters). Valid options:
-
Hex color codes
-
RGB or RGBA syntax
-
Standard CSS color names (e.g. 'blue')
Sets the left margin value applied to videos (in any layout mode), in grid units. You can use these videoSettings.margin.* params to shrink the video area, for example to make room for overlays.
Sets the right margin value applied to videos (in any layout mode), in grid units. You can use these videoSettings.margin.* params to shrink the video area, for example to make room for overlays.
Sets the top margin value applied to videos (in any layout mode), in grid units. You can use these videoSettings.margin.* params to shrink the video area, for example to make room for overlays.
Sets the bottom margin value applied to videos (in any layout mode), in grid units. You can use these videoSettings.margin.* params to shrink the video area, for example to make room for overlays.
Group: text
Sets the data source used for the text displayed in the overlay. The default value 'param' means that the value of param text.content is used. Valid options: param, highlightLines.items, chatMessages, transcript
Sets the horizontal alignment of the text overlay within the video frame. Values are left, right, or center.
Sets the vertical alignment of the text overlay within the video frame. Values are top, bottom, or center.
Sets an x-offset (horizontal) to be applied to the text overlay's position based on the values of text.align_horizontal and text.align_vertical.
Sets a y-offset (vertical) to be applied to the text overlay's position based on the values of text.align_horizontal and text.align_vertical.
Applies a rotation to the text overlay. Units are degrees, and positive is a clockwise rotation.
Sets the font of the text overlay. Valid options: DMSans, Roboto, RobotoCondensed, Anton, Bangers, Bitter, Exo, Magra, PermanentMarker, SuezOne, Teko
Selects a weight variant from the selected font family. Valid options: 100, 200, 300, 400, 500, 600, 700, 800, 900.
Note: Not all font weights are valid for every font family.
Sets the text overlay font size using grid units (gu). By default, one grid unit is 1/36 of the smaller dimension of the viewport (e.g. 20px in a 1280*720 stream).
Sets the color and transparency of the text overlay. Valid options:
-
Hex color codes
-
RGB or RGBA syntax
-
Standard CSS color names (e.g. 'blue')
Sets the color of the stroke drawn around the characters in the text overlay. Valid options:
-
Hex color codes
-
RGB or RGBA syntax
-
Standard CSS color names (e.g. 'blue')
Sets the width of the stroke drawn around the characters in the text overlay. Specified in grid units.
Sets the color and transparency of a highlighted item in the text overlay. To display a highlight, the value of param text.source must be set to highlightLines.items. Valid options:
-
Hex color codes
-
RGB or RGBA syntax
-
Standard CSS color names (e.g. 'blue')
Sets the font weight of a highlighted item in the text overlay. To display a highlight, the value of param text.source must be set to highlightLines.items.
Group: image
Sets the overlay image. Icon asset must be included in session_assets object. showImageOverlay must be true.
Sets an emoji to be rendered instead of an image asset. If this string is non-empty, it will override the value of image.assetName. The string value must be an emoji.
Sets position of overlay image. Valid options: 'top-left', 'top-right', 'bottom-left', 'bottom-right'
Sets margin between the overlay image and the viewport edge, in grid units.
Sets opacity of overlay image, in range 0-1. Default value of 1 is full opacity.
Sets the overlay image to fade in or out when the showImageOverlay property is updated.
Group: webFrame
Sets the web page URL to be loaded into the WebFrame overlay's embedded browser.
Sets the width of the embedded browser window used to render the WebFrame overlay.
Sets the height of the embedded browser window used to render the WebFrame overlay.
Sets position of the WebFrame overlay. Valid options: 'top-left', 'top-right', 'bottom-left', 'bottom-right'
Sets margin between the WebFrame overlay and the viewport edge, in grid units.
Sets opacity of the WebFrame overlay, in range 0-1. Default value of 1 is full opacity.
Sets the WebFrame overlay to fade in or out when the showWebFrameOverlay property is updated.
Sets the keyboard key to be sent to the WebFrame browser in a simulated key press. Valid options:
- Digits 0 - 9
- Letters A - Z
- ASCII special characters, e.g. !, @, +, >, etc.
- Function keys F1 - F12
- Enter
- Escape
- Backspace
- Tab
- Arrow keys ArrowUp, ArrowDown, ArrowLeft, ArrowRight
- PageDown, PageUp
Sets keyboard modifier keys to be sent to the WebFrame browser in a simulated key press. Valid options: "Shift", "Control", "Alt", "Meta" (on a Mac keyboard, Alt is equal to Option and Meta is equal to Command).
Triggers a simulated key press to be sent to WebFrame. To send a key press, increment the value of key. (Note the difference between this and keyName which is the simulated key to be sent.)
Group: banner
Sets the subtitle text displayed in the banner component.
Sets the data source for the text displayed in the banner component. Valid options: param, highlightLines.items, chatMessages, transcript
Sets position of the banner component. Valid options: 'top-left', 'top-right', 'bottom-left', 'bottom-right'
Sets the banner to fade in or out when the showBannerOverlay property is updated.
Sets whether the banner component will always use its maximum width (specified using banner.maxW_pct_default and banner.maxW_pct_portrait). If false, the banner component will shrink horizontally to fit text inside it, if appropriate.
Sets the maximum width for the banner component, as a percentage of the viewport size.
Sets the maximum width for the banner component, as a percentage of the viewport size, applied only when the viewport aspect ratio is portrait (i.e. smaller than 1). This override is useful because on a narrow screen the banner display typically needs more horizontal space than on a landscape screen.
Applies a rotation to the banner component. Units are degrees, and positive is a clockwise rotation.
Sets the corner radius of the banner component outline. Specified in grid units.
Sets whether an icon is displayed in the banner component (true or false).
Sets image asset value for the banner icon. Icon asset must be included in session_assets object.
Sets an emoji to be rendered as the banner icon. If this string is non-empty, it will override banner.icon.assetName. The string value must be an emoji.
Sets the banner component's background color. Valid options:
-
Hex color codes
-
RGB or RGBA syntax
-
Standard CSS color names (e.g. 'blue')
Sets the color of the outline drawn around the banner component. Valid options:
-
Hex color codes
-
RGB or RGBA syntax
-
Standard CSS color names (e.g. 'blue')
Sets the width of the stroke drawn around the banner component. Specified in grid units.
Sets the banner component's text color. Valid options:
-
Hex color codes
-
RGB or RGBA syntax
-
Standard CSS color names (e.g. 'blue')
Sets the color of the stroke drawn around the characters in the banner component. Valid options:
-
Hex color codes
-
RGB or RGBA syntax
-
Standard CSS color names (e.g. 'blue')
Sets the width of the stroke drawn around the characters in the banner component. Specified in grid units.
Sets the font of text displayed in the banner component. Valid options: DMSans, Roboto, RobotoCondensed, Anton, Bangers, Bitter, Exo, Magra, PermanentMarker, SuezOne, Teko
Sets the banner title font size using grid units (gu). By default, one grid unit is 1/36 of the smaller dimension of the viewport (e.g. 20px in a 1280*720 stream).
Sets the banner title font weight. Valid options: 100, 200, 300, 400, 500, 600, 700, 800, 900.
Note: Not all font weights are valid for every font family.
Sets the font style for the banner title. Valid options: 'normal','italic'.
Sets the banner subtitle font size using grid units (gu). By default, one grid unit is 1/36 of the smaller dimension of the viewport (e.g. 20px in a 1280*720 stream).
Sets the banner subtitle font weight. Valid options: 100, 200, 300, 400, 500, 600, 700, 800, 900.
Note: Not all font weights are valid for every font family.
Sets the font style for the banner subtitle. Valid options: 'normal','italic'.
Group: toast
Triggers display of toast component. To send a toast, increment the value of key
Sets the data source used for the text displayed in the toast component. The default value param means that the value of param toast.content is used. Valid options: param, chatMessages, transcript
Sets the maximum width for the toast component, as a percentage of the viewport size.
Sets the maximum width for the toast component, as a percentage of the viewport size, applied only when the viewport aspect ratio is portrait (i.e. smaller than 1). This override is useful because on a narrow screen the toast display typically needs more horizontal space than on a landscape screen.
Sets whether icon is displayed in toast component (true or false).
Sets asset value for toast icon. Icon asset must be included in session_assets object.
Sets an emoji to be rendered as the toast icon. If this string is non-empty, it will override toast.icon.assetName. The string value must be an emoji.
Sets the toast component's background color. Valid options:
-
Hex color codes
-
RGB or RGBA syntax
-
Standard CSS color names (e.g. 'blue')
Sets the color of the stroke drawn around the text characters in the toast component. Valid options:
-
Hex color codes
-
RGB or RGBA syntax
-
Standard CSS color names (e.g. 'blue')
Sets the toast component's text color. Valid options:
-
Hex color codes
-
RGB or RGBA syntax
-
Standard CSS color names (e.g. 'blue')
Sets the toast component's font family. Valid options: DMSans, Roboto, RobotoCondensed, Bitter, Exo, Magra, SuezOne, Teko
Sets the font weight for the toast component's text. Valid options: 100, 200, 300, 400, 500, 600, 700, 800, 900.
Note: Not all font weights are valid for every font family.
Group: openingSlate
Sets the number of seconds that the opening slate will be displayed when the stream starts. After this time, the slate goes away with a fade-out effect.
Sets text displayed in the subtitle (second line) of the opening slate.
Sets an image to be used as the background for the slate. This image asset must be included in session_assets object when starting the stream/recording.
Sets the slate's background color. Valid options:
-
Hex color codes
-
RGB or RGBA syntax
-
Standard CSS color names (e.g. 'blue')
Sets the text color of the titles in the slate. Valid options:
-
Hex color codes
-
RGB or RGBA syntax
-
Standard CSS color names (e.g. 'blue')
Sets the font of the titles in the slate. Valid options: DMSans, Roboto, RobotoCondensed, Anton, Bangers, Bitter, Exo, Magra, PermanentMarker, SuezOne, Teko
Selects a weight variant from the selected font family. Valid options: 100, 200, 300, 400, 500, 600, 700, 800, 900.
Note: Not all font weights are valid for every font family.
Sets the font style for the titles in the slate. Valid options: 'normal','italic'.
Sets the main title font size using grid units (gu). By default, one grid unit is 1/36 of the smaller dimension of the viewport (e.g. 20px in a 1280*720 stream).
Sets the subtitle font size as a percentage of the main title.
Selects a weight variant from the selected font family specifically for the subtitle. Valid options: 100, 200, 300, 400, 500, 600, 700, 800, 900.
Note: Not all font weights are valid for every font family.
Group: titleSlate
Sets the slate to fade in or out when the showTitleSlate property is updated.'
Sets text displayed in the subtitle (second line) of the slate.
Sets an image to be used as the background for the slate. This image asset must be included in session_assets object when starting the stream/recording.
Sets the slate's background color. Valid options:
-
Hex color codes
-
RGB or RGBA syntax
-
Standard CSS color names (e.g. 'blue')
Sets the text color of the titles in the slate. Valid options:
-
Hex color codes
-
RGB or RGBA syntax
-
Standard CSS color names (e.g. 'blue')
Sets the font of the titles in the slate. Valid options: DMSans, Roboto, RobotoCondensed, Anton, Bangers, Bitter, Exo, Magra, PermanentMarker, SuezOne, Teko
Selects a weight variant from the selected font family. Valid options: 100, 200, 300, 400, 500, 600, 700, 800, 900.
Note: Not all font weights are valid for every font family.
Sets the font style for the titles in the slate. Valid options: 'normal','italic'.
Sets the main title font size using grid units (gu). By default, one grid unit is 1/36 of the smaller dimension of the viewport (e.g. 20px in a 1280*720 stream).
Sets the subtitle font size as a percentage of the main title.
Selects a weight variant from the selected font family specifically for the subtitle. Valid options: 100, 200, 300, 400, 500, 600, 700, 800, 900.
Note: Not all font weights are valid for every font family.
Group: sidebar
Sets whether the sidebar is displayed on top of video elements. If set to true , the video layout is shrunk horizontally to make room for the sidebar so they don't overlap.
Sets the data source for the text displayed in the sidebar. Valid options: param, highlightLines.items, chatMessages, transcript
Sets the width of the sidebar, as a percentage of the viewport size, applied when the viewport is landscape (its aspect ratio is greater than 1).
Sets the width of the sidebar, as a percentage of the viewport size, applied when the viewport is portrait or square (its aspect ratio is less than or equal to 1).
Sets the sidebar's background color and opacity. Valid options:
-
Hex color codes
-
RGB or RGBA syntax
-
Standard CSS color names (e.g. 'blue')
Sets the sidebar's text color and opacity. Valid options:
-
Hex color codes
-
RGB or RGBA syntax
-
Standard CSS color names (e.g. 'blue')
Sets the font of text displayed in the sidebar. Valid options: DMSans, Roboto, RobotoCondensed, Anton, Bangers, Bitter, Exo, Magra, PermanentMarker, SuezOne, Teko
Sets the sidebar text font weight. Valid options: 100, 200, 300, 400, 500, 600, 700, 800, 900.
Note: Not all font weights are valid for every font family.
Sets the font style for text in the sidebar. Valid options: 'normal','italic'.
Sets the sidebar text font size using grid units (gu). By default, one grid unit is 1/36 of the smaller dimension of the viewport (e.g. 20px in a 1280*720 stream).
Sets the color used for the highlighted item in the sidebar.
Sets the font weight used for the highlighted item in the sidebar.
Group: highlightLines
Sets a list of text items. Items must be separated by newline characters. This param is a data source that can be displayed in other components like TextOverlay, Banner and Sidebar using the various "source" params available in the settings for those components.
Sets the highlight index associated with the text items specified in highlightLines.items. The item at this index will be displayed using a special highlight style (which depends on the component used to display this data). If you don't want a highlight, set this value to -1.
Group: emojiReactions
Sets the data source used for emoji reactions. The default value emojiReactions means that this component will display emojis that are sent via the standard source API.
The other valid option is param, which lets you send a reaction using param values instead of the standard source. The steps are as follows: set emojiReactions.source to param, set a single-emoji string for emojiReactions.emoji, and increment the value of emojiReactions.key to send one emoji for display.
If emojiReactions.source is set to param, increment this numeric key to send a new emoji for display.
If emojiReactions.source is set to param, set a single emoji as the string value for this param, and it will be the next emoji reaction rendered when emojiReactions.key is incremented.
Sets a horizontal offset applied to the emoji reactions animation rendering (each new emoji floats up from the bottom of the screen). Specified in grid units.
Group: debug
When set to true, a room state debugging display is visible. It prints various information about participant state.
Sets the opacity of the debugging display which can be toggled using debug.showRoomState.
Selecting participants
The baseline composition has several modes that display multiple participant videos. You may be wondering how to control which participants appear in specific places within those layouts.
Internally, VCS uses an ordered array of video inputs that it calls "video input slots". By default, that array will contain all participants in the order in which they joined the call. But there are two ways you can override this default behavior and choose which participants appear in your layout:
- Participant selection on the room level using the
participantsproperty. - Input reordering on the composition level (a.k.a. switching) using the
preferredParticipantIdsandpreferScreenshareparams available in the baseline composition.
These two are not mutually exclusive. What's the difference, and when should you use one or the other?
Room-level participant selection is a powerful generic tool. It lets you choose any participants within the room, and will trigger any necessary backend connections so that a participant's audio and video streams become available to the VCS rendering server. This means there may be a slight delay as connections are made.
In contrast, composition-level input reordering (a.k.a. switching) happens at the very last moment in the VCS engine just before a video frame is rendered. (The name "switching" refers to a video switcher, a hardware device used in traditional video production for this kind of input control.) It's applied together with any other composition param updates you're sending, so there is a guarantee of synchronization. You should use this method when you want to ensure that the reordering of inputs happens precisely at the same time as your update to some other composition param value(s). For example, if you're switching a layout mode and want the inputs to be sorted in a different way simultaneously.
You can use the two methods together. Room-level selection using the participants property lets you establish the participants whose streams will be available to the rendering. You can then do rapid switching within that selection using the preferredParticipantIds and preferScreenshare params in the baseline composition.
Here's an example of selecting three specific participant video tracks, everyone's audio tracks, and sorting the video by most recent active speaker:
Here's another example where we're further sorting the same video tracks using the baseline composition params. The params update is switching to a different layout mode ('split'). This mode can only show two participants, so we use videoSettings.preferredParticipantIds to select the two participants in a clean frame-synchronized way, without having to modify the underlying connections made via the participants property:
If you include the participants object in a startLiveStreaming()/startRecording() or updateLiveStreaming()/updateRecording() call, you need to include it in any subsequent updateLiveStreaming()/updateRecording() calls as well, even if you aren't changing it.
If you set the participants property for your recording or live stream and then make an updateLiveStreaming()/updateRecording() call to update the composition_params, you'll need to resend the same values you used before in the participants property. This is true even if you are not updating the participants property. If you don't, the participant configuration will reset to default, as if you hadn't set it in the first place —meaning VCS will receive all audio and video tracks from all participants, sorted by the order in which the participants joined the call.
participants properties
Required. An array of strings indicating which participant videos to make available to VCS. Possible values are:
-
["participant-guid-1", "participant-guid-2", "participant-guid-3"]: A list of specific participant IDs -
["*"]: everyone -
["owners"]: All call owners
An optional array of strings indicating which participant audio tracks to make available to VCS. Possible values are the same as the video property.
The only currently valid value for this property is "active". This property controls the order in which VCS sees the participant video tracks. When set to "active", each time the call's active speaker changes to a different participant, that participant will bubble up to the first position in the array. In other words, setting sort to "active" will cause an n-tile layout to always show the n most recent speakers in the call. If you leave the property unset, the list of participants will stay in a fixed order: either the order you specified in the video property, or in the order they joined the call if you use "*" or "owners".
Session assets
Session assets — images or custom VCS components — that can be passed as assets and used during a live stream or cloud recording. To learn more, visit our Session assets page in the VCS SDK reference docs.
Note: Session assets must be made available at the beginning of the recording or live stream even if they are not used until later in the call.