Secure Reliable Transport (SRT) is a video transport protocol that optimizes streaming performance over unpredictable networks. With built-in security and low latency, SRT provides the best quality live video, even in unstable network conditions. The SRT protocol is supported for RMS live sources.
In this guide, you’ll learn how to:
- Set up an SRT stream.
- Connect Open Broadcaster Software (OBS) to stream via SRT.
In addition, you’ll understand key considerations, including how to transition your live event setup from RTMP to SRT.
In this article:
Stream using SRT
By default, SRT is disabled on the platform. You can request Ravnur to enable SRT by specifying the number of simultaneous live events you plan to host. If no ports are open for SRT, you will see the error: “No ports allocated for SRT live streaming, please contact Ravnur.”
Once SRT is enabled, the configuration typically allows for a limited number of SRT sources. If you attempt to create additional sources beyond this limit, you will see the error: “Failed to reserve SRT port, please contact Ravnur.”
To resolve this, you can either delete an existing source to free up a reserved port or contact Ravnur support to increase the limit.
Add a live source
The setup for streaming via SRT follows the standard process: creating a live source, configuring a channel, and scheduling a live event.
To stream via the SRT protocol, start with creating a live source:
1. Navigate to Live Streaming > Configure sources.
2. Click Create Live Source and select Ravnur Media Services as the source type.
3. Choose any Account and Encoding option. SRT is supported for all configurations.
4. In the Ingest stream protocol field, select SRT.
5. Complete the remaining fields and click Create Live Source.
Tip: Name the source to indicate it’s an SRT stream to recognize it later.
Retrieve URL
The created live source includes the Ingest URL (SRT) on its page, an endpoint where your video stream is sent for processing. You need to copy it for the encoder setup.
Optionally, select Show separate fields to open detailed parameters:
-
Hostname / URL / Port: The address of the SRT server where your stream will be sent (e.g.,
srtlive.{unique-value}.ravnur.net:10000). -
Stream key: A unique identifier for your stream, embedded in the URL as
streamid. -
Bandwidth: The maximum transmission bandwidth for the stream, in bits per second (by default,
50000000being 50 Mbps). -
Latency: The buffer time (in milliseconds) used to handle network delays for smooth streaming (by default,
1000ms). - Passphrase: A security key used for encrypting the stream.
The fields are pre-configured with recommended values for a reliable stream. They can only be copied for use with encoders requiring detailed setup, such as Wirecast or others.
If you need these values changed, contact Ravnur support.
Configure OBS
Once you have the ingest URL from the Live Source page (or Control Room page), follow these steps to configure OBS:
1. Open Settings in OBS and navigate to Stream.
2. Paste the ingest URL into the Server field.
OBS accepts the SRT endpoint as a single URL, and it is already structured as shown below:
Stream Key should be left empty as both the Stream ID (representing a Stream Key) and the Passphrase are being set in the URL field.
Finalize the setup
After configuring OBS, set up the channel with the SRT source you created. Next, schedule your live event with this source.
At this point, you are ready to preview and go live from the Control Room:
Considerations
- SRT supports all available encoding options, including Standard passthrough, Standard 720p ABR, and Premium 1080p ABR.
- Once a live source is created, the ingest stream protocol (SRT or RTMP) cannot be changed. To transition a channel from RTMP to SRT, create a new SRT live source and update the Default live source for the channel.
- While you can use DVR features with MPEG-DASH, it cannot be combined with adaptive bitrate (ABR) streaming. If you need an ABR stream with DVR, use HLS instead of MPEG-DASH.
- CEA-708 and EIA-608 closed captions are not supported with SRT.
Network
In most cases, SRT streaming works without additional setup. However, in restricted network environments, such as corporate or educational networks, UDP traffic may sometimes be blocked. If streaming fails, ensure that firewalls or policies allow UDP traffic, or ask your network administrator to check this.
You have successfully configured SRT as your live ingest type, set up and tested your stream using OBS, and learned the advantages and limitations of SRT with the Ravnur Media Platform.
With your SRT stream now ready, you can create secure, low-latency live broadcasts optimized for challenging network conditions.