Nimble Streamer and Secure Reliable Transport

Secure Reliable Transport (SRT) is a technology that optimizes streaming performance in unpredictable networks. It helps to deliver high-quality video content by compensating for jitter and bandwidth fluctuations. SRT is also equipped with AES 128/256-bit encryption to ensure end-to-end security for your streams.

Nimble Streamer, a product of Softvelum, has full support for the SRT protocol. It supports both Caller (Push) and Listen delivery modes, as well as Rendezvous mode. Custom latency and maxbw parameters are supported for re-transmission control, and AES-128 bit encryption provides stream security. Additionally, IPv4 and IPv6 are both supported, and streamid parameter support is available in Caller (Push) and Pull modes.

Softvelum is an active member of the SRT Alliance, a group dedicated to supporting the open-source implementation of SRT.

SRT is applied to contribution and distribution endpoints as part of a video stream workflow to deliver the best quality and lowest latency video at all times.

Supported codecs include H.264/AVC, H.265/HEVC, AV1 and others.

Some highlights of SRT include the following.

• SRT detects and adapts to the real-time network conditions between the two endpoints.
• SRT helps compensate for jitter and bandwidth fluctuations due to congestion over noisy networks.
• Error recovery mechanism minimizes the packet loss typical of Internet connections.
• AES 128/256 bit encryption is also supported for end-to-end security, keeping your streams safe from prying eyes.

SRT support in Nimble Streamer

Nimble Streamer has full support for SRT protocol.

• Both Push (Caller) and Listen delivery modes are supported
• Both Listen and Pull receive modes can be used to get SRT streams for further processing.
• Rendezvous mode can be used for both receiving and sending data.
• Custom latency and maxbw parameters are supported for re-transmission control, we highly recommend using them both for all connections.
• One-to-many multi-point listener: multiple Pull-mode clients can be supported when working in "Listen" mode.
• Connection bonding to receive SRT streams, if using libsrt 1.5.0.
• SRT playback stats and paywall protection feature set similar to other playback protocols.
• FEC (forward error correction) filter is supported.
• AES-128 bit encryption provides stream security.
• Both IPv4 and IPv6 are supported.
• Multiple programs can be sent via single SRT channel.
• You can use Nimble Streamer API to get SRT sender and receiver statuses.

streamid parameter support

• Nimble supports streamid in Push and Pull modes.
• In addition, Nimble supports streamid in receiver Listen mode as part of Publisher Assistance Security Set.

Installation and Usage

Premium features

Some SRT-related functionality is available as part of our premium Addenda package.

Pull SRT in RTMP style: Nimble Streamer supports SRT Listen mode with streamid in appname/streamname format to pull any available live stream. This allows using single IP and port to get multiple streams by their names, just like in RTMP.

SRT flexible publication management: SRT Publisher Assistance Security Set (SRT PASSet)
Nimble Streamer provides wide security and management feature set for SRT receiver Listen mode.

• Accept streamid parameter with "application/stream" format.
• Make per-application and per-stream authentication with user and password.
• Apply any SRT parameters to each individual stream and even individual publisher.
• Apply allow and deny lists for IP addresses on server and stream level.
• Manage published streams via publish control framework.

Please read the following articles to learn more about PASSet:

• Technology overview article.
• User/password authentication and application/stream publication.
• Setting per-stream authentication and SRT parameters with JSON config file.

Additional SRT features for SRT Listen mode:

• SRT playback statistics
• SRT paywall protection

This feature set makes pulled SRT similar to other playback protocols to be even more convenient protocol for content providers for end-users.

Hot swap
Hot swap capabilities allow switching between source origin and substitute streams with no glitches or artifacts:

• Emergency hot swap to cover cases like U.S. Emergency Alert System.
• Failover hot swap to show tuning table or other active channel in case the stream goes down.

These features are available for SRT once you enable instant inactivity disconnect for MPEGTS-based streams for your server instance.
It also requires Live Transcoder premium add-on.

SRT in other products

In addition to Nimble Streamer, SRT is supported in all major products of Softvelum.

• Larix Broadcaster streaming app for remote contribution on Android and iOS.
• Larix Player for Android, AndroidTV, iOS and tvOS

Visit SRT reference page for more information and links.