Hosting a webinar with SRT livestream

SRT (Secure Reliable Transport) lets you stream high-quality, professional video content directly into your Zoom Events, in addition to the existing RTMP option. SRT provides lower latency and improved reliability over unpredictable networks by using packet retransmission and built-in encryption. You can select and configure SRT directly from the livestream tab during a session, using the same workflow available for RTMP ingest.

Requirements for hosting a webinar with SRT livestream

• Zoom Events Unlimited license or Zoom Events Pay Per Attendee license; or, Zoom Webinars Plus Unlimited or Zoom Webinars Plus Pay Per Attendee license
• Host or co-host of the webinar
• Scheduled Zoom Event with Incoming livestream enabled
• Zoom desktop app for Windows or macOS, version 6.2.0 or later
• Encoder software that supports SRT output (for example, OBS, vMix, or Haivision)
  Note: Confirm your encoder is set to H.264.
• A stable and fast internet connection with the recommended minimum upload speeds:
  • For 720p30 quality: 4 Mbps
  • For 1080p30 quality: 6 Mbps

Best practices for an incoming SRT livestream

Before going live, test your SRT connection and encoder settings to confirm video and audio quality. Use a wired internet connection whenever possible for the most reliable stream.

Video quality best practices

• Use H.264 encoding at up to 1080p at 30 fps.
• Set the rate control to CBR (Constant Bitrate) or tightly constrained VBR.
• Set the keyframe interval to 1–2 seconds (for example, every 30 frames at 30 fps).
• Keep your total stream bitrate comfortably below your measured upload capacity. Reserve roughly 20–30% network headroom for SRT retransmissions.

Audio quality best practices

• Use AAC audio at 128–192 Kbps.
• Set the sample rate to 44.1 kHz or 48 kHz.
• Use stereo audio for the best listener experience.

Best practices for an SRT livestream

• Test your full SRT workflow before the live event to confirm encoder settings, network stability, and stream quality.
• Use a wired Ethernet connection rather than Wi-Fi.
• Run your SRT encoder on a separate device from the one hosting the Zoom webinar.
• Have a backup plan in case of connection issues. Consider keeping RTMP configured as a fallback.
• Monitor SRT stream health metrics during the session, including round-trip time (RTT), packet loss, and retransmission rate.

How to host a webinar with SRT livestream

Select SRT as the ingest protocol

1. Start the webinar.
2. In the meeting controls, click More.
3. Click Live on Custom Live Streaming Service.
   The livestream configuration panel opens.
4. In the livestream tab, select SRT as the streaming protocol.
   The panel updates to show SRT-specific configuration fields.

Configure and start the SRT stream

1. In your encoder software (for example, OBS or vMix), configure the output to use SRT.
   Notes:
   • You can copy the stream URLs and stream key from the Incoming livestream (SRT) configuration in multi-session, single-session full, single-session lite, and recurring sessions events.
   • Refer to your software's documentation for detailed instructions on how to apply an SRT stream URL, stream ID, and passphrase for your encoder.
   • Two stream URLs can be used for automatic redundancy, if your platform only allows for a single stream, then use the first stream.
2. Copy the SRT ingest URL from the Zoom livestream panel and paste it into your encoder's destination field.
3. Start the stream in your encoder software. The incoming SRT stream appears in the Zoom livestream panel.
4. In the panel, view and manage the following:
   • At the top of the panel, view the preview of the stream that goes through the third-party application.
     • Click Send live to send the stream to the webinar. If a confirmation window appears, click Send.
       Everyone will see the stream in the webinar.
     • On the stream preview, move the volume slider to adjust the volume, or mute the volume. This will control the volume for all participants in the webinar.
     • Click Stop sending to stop sending the stream to the webinar.
   • Click the Stream metrics tab to view the incoming streaming metrics:
     Note: The Stream metrics show the health of the stream as it is coming from the third-party app into Zoom. If you want to see the webinar metrics (in general), click the gear icon from the security shield at the top of the webinar and view the webinar metrics under Statistics.
     • Bitrate: The amount of data transmitted per second in a live stream
     • Frame rate: The number of individual image frames displayed per second in a video or live stream
     • Bandwidth: The maximum amount of data that can be transmitted over an internet connection per second
     • Video resolution: The number of pixels that make up each frame of a video that determines how sharp, clear, and detailed the image looks
     • Closed caption language: The language in which the captions (on-screen text) are displayed during a live stream
     • View the metrics on the chart for more detailed data.
   • Click the Stream health tab to view the feed of how the stream is performing.
     • View the current overall Stream status. It can range from No data if the stream is not active. Depending on your network bandwidth, it can also read as Excellent, Good, Bad, and Especially Bad.
     • Under Messages, view the message feed of the stream's health to see historically all the performance events for the livestream.
5. When you are finished streaming, return to your third-party app to stop the stream.

Switch between SRT and RTMP

You can switch the ingest protocol between SRT and RTMP from the livestream tab during a session. Select the protocol you want to use, then reconfigure your encoder to match.

Note: Switching protocols during an active stream requires you to stop the current stream, change the protocol selection, and restart the stream from your encoder.

How to change the speaking language for live captions

By default, live captions in SRT sessions use the speaking language configured in the Zoom Events web portal. You can also change the language during a live session without stopping the stream.

1. During an SRT livestream session, open the SRT panel.
2. Click the Speaking language dropdown.
3. Select the language you want live captions to display in.
   The captions update to the selected language immediately.