SRT

Using Secure Reliable Transport (SRT) to publish to Dolby.io Real-time Streaming

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Beta

New functionalities mentioned in this document are a part of the Beta program. The program offers pre-GA Client SDKs and APIs that allow customers to evaluate upcoming features before their General Availability.

SRT (Secure Reliable Transport) is an open-source protocol that uses an intelligent packet retransmit mechanism on top of a UDP data flow, along with AES-128 and 256-bit encryption. Dolby.io Real-time Streaming natively supports publishing from an SRT source.

This document will guide you on how to use the SRT feature from Dolby.io Real-time Streaming with SRT-capable software or hardware.

SRT Publishing Requirements

Log into the Dolby.io dashboard and go to the Live Broadcast section. If you have not yet created a token, please do so now. To learn how to create a basic token you can read Creating a Basic Token in the How to Broadcast document.

Open the publishing token's details by clicking the Manage Token button from the item’s action menu.

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Click on the API tab for information on how to connect as a publisher and subscriber to your account.

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In order for you to publish to Dolby.io Real-time Streaming with SRT you will need two things from the form, the SRT publish path and SRT stream ID (which includes your unique Stream Name and Publishing Token).

This information will authenticate you as a publisher on Dolby.io Real-time Streaming and allow you to successfully broadcast from an SRT source using your account.

How the SRT publish path and SRT stream ID values are used is dependent on your software or hardware device. For example, some devices/encoders accept the values as separate parameters and some require them combined as a single URL. If your encoder has a separate streamId field, you will want to provide the SRT publish path and the SRT stream ID fields from the dashboard.
If your encoder only has a single field for SRT, use the SRT publish URL.

The following are examples of how these values can be used:

  • Combined as a single SRT publish URL: srt-publish-path?streamid=encoded-srt-stream-id. In the screen above the example is srt://live-rtmp.pub.millicast.com:10000?streamid=lb3s4dgh%253-t%253DQPSIn....
  • As two separate fields, the SRT publish path and SRT stream ID. In the screen above, the examples are srt://live-rtmp.pub.millicast.com:10000 and lb3s4dgh?t=QPSln8l1JM6xgfVJOw3oIN4CkpAbrcPRGlj3QxNKJ1w.

SRT Limitations

The following are current limitations of the SRT feature from Dolby.io Real-time Streaming:

  • Only H.264 video and AAC audio codecs are currently supported
  • Multiple programs or substreams are not supported
  • You cannot use the "auto" region for a publishing key; you must specify a region for the SRT and RTMP paths and keys to populate in the dashboard.
  • Recording is currently not supported

If you have any questions or suggestions feel free to contact us.