Tips & Tricks

RTMP Streaming Protocol Explained: All You Need to Know4 min read

October 2, 2020 4 min read
RTMP Streaming Protocol Explained

RTMP Streaming Protocol Explained: All You Need to Know4 min read

Reading Time: 4 minutes

What is RTMP?

RTMP, short for Real-Time Messaging Protocol, is a protocol for streaming audio, video, and data over the Internet. The RTMP specification is created by Macromedia and later on owned by Adobe. 

Initially, the protocol helps deliver media and live media over the Internet between a Flash player and a server. Today, RTMP is most commonly used for encoding streams, leveraging its constant connection between the video player and the server.

Because of Adobe’s announcement for their end of support for Flash Player in 2020, RTMP protocol usage has declined substantially in recent years. However, that does not mean that it is out of the picture in the livestreaming market. The Real-Time Messaging Protocol is still much loved by the streaming community as one of the encoding video standards.

What is an RTMP stream?

RTMP is a TCP-based protocol that splits the stream into small chunks of information to make it more versatile and flow more smoothly. Although the Flash Player technology is getting near its deprecating day, RTMP remains one of the top choices of streaming platforms.

It is being used as an ingest protocol by Facebook Live, YouTube, and even Twitch. The combination of Flash Player and RTMP makes it possible for considerably low latency when streaming, along with a robust and reliable connection. 

A typical stream using RTMP protocol in Castr

Most livestreaming services and encoders today are using the RTMP format. RTMP is highly effective in maintaining low latency for streams with stable audio and video connections.  

As a result, the majority of livestreaming community is choosing to transmit the media to an RTMP server to best leverage the protocol’s advantages. The streamers will then transcode it into other technologies like HLS, DASH, or SRT for multi-device delivery.

Today, a stream typically combines RTMP and HLS protocols for low latency and adaptive quality for the viewers. 

A particular stream setup with RTMP protocol would look like this:

  • Record the stream with an RTMP-compatible camera or encoder.
  • You can choose between an IP camera, software encoder, or hardware encoder. A popular choice is the free OBS software.
  • Once the recording and encoding finish, it is then converted to another protocol for better egress quality.

Here’s how you can do it with Castr:

  1. Head over to Castr’s dashboard
  2. Open your project
  3. Copy the RTMP ingest URL and Streaming Key Get RTMP details for livestreaming
  4. Paste into your encoder’s RTMP configuration

Although your video and audio input use the RTMP protocol, Castr gives you many options for the stream output, including RTMP, RTSP, HLS, and MPEG-TS. 

Once you have successfully set up the stream, it is best to have a test run to see if your setup, along with all the stream’s specifications, run as planned before actually going live.

Alternative protocols for RTMP

HLS Streaming Protocol

Developed by Apple, HLS is one of the HTTP-based streaming protocols that most streamers love for its versatility. 

HLS, short for HTTP Live Streaming, is made to be compatible with most devices, including iOS and Android operating systems. The HLS protocol takes advantage of the standard web server and content distribution networks. It optimizes the scalability of the stream, simultaneous viewing, and accessibility for a more extensive audience.

RTMP and HLS Protocols

HLS allows you to reach the maximum possible viewers with your livestream, while RTMP helps your audio and video’s stability and quality. The combination of RTMP and HLS is most famous as the encoder and transmitter pair to deliver the best streaming quality possible.

If you are using streaming services, encoding the RTMP ingest to HLS is done automatically on the server end. For example, when you stream with Castr the RTMP stream is ingested and then transcoded to HLS in almost no time. Castr will then push the stream to your viewers via our worldwide servers, accessible by any end-device and with low latency.

MPEG-DASH Protocol

DASH is an open-sourced, HTTP-based protocol designed to be the competitor to HLS from Apple. The protocol is an adaptive bitrate video method that supports DRM, HTTP delivery, lower-latency streaming, making it a standard in the industry.

RTSP Streaming Protocol

RTSP is short for Real-Time Streaming Protocol to control the streaming servers used in entertainment and communications systems. The RTSP is a presentation-layer protocol for the end-users to command media servers via the pause and play capabilities.


Your choice of streaming protocol depends mainly on your demand and use case. Each protocol has its pros and cons as you look deeper into each. Although RTMP is no longer in the spotlight due to its close relationship with Flash Player, it is still a proven streaming technology for those who are in the livestreaming market.

To generate the highest stream quality, we suggest that you choose RTMP as the ingest source and HLS or DASH to be the playback protocol. If you feel lost in the choices for livestreaming platforms, give Castr a try to see how going live can be simple as 1 2 3 — leave all the technical concerns to us and start streaming with confidence. 

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