Enhanced RTMP (E-RTMP) now in MistServer

One of t he new features in MistServer 3.9 is support for Enhanced RTMP (E-RTMP). You might be wondering what is E-RTMP and how would I use it?

What is E-RTMP?

E-RTMP is an evolution of Adobe RTMP allowing for additional codecs and features. It is in development by Veovera Software Organization and more about it can be read here. We'll give you some bullet points about what makes E-RTMP a nice option to have in your streaming toolkit.

Backwards compatibility

• Using E-RTMP will not cause conflicts with older RTMP users

E-RTMP is backwards compatible with RTMP. Now this doesn't mean that old normal RTMP endpoints will enjoy the additional features from E-RTMP, what it does mean is that E-RTMP can see the other endpoint isn't E-RTMP capable and will downgrade to fit normal RTMP.

Improved codec support

• More modern codec support has been added

E-RTMP updates existing modern protocols (H264, AAC, MP3) and adds additional codec support for Video and Audio.

• Video: HEVC, VP8, VP9, AV1
• Audio: Opus, FLAC, AC3

Now the additional codec support is a welcome addition as it allows much better quality video for a lower bandwidth. However until there are more E-RTMP capable applications/devices this does mean that you are locked to always providing at least a traditional H264 video and AAC or MP3 audio track. Otherwise your stream will not be accepted at these endpoints.

Multi-track support

• Easier to stream multiple video/audio qualities in one stream

Now to be completely honest, this isn't quite new as the old RTMP specification allowed for multi-track video/audio as well. It's just that E-RTMP has this done a bit more modern and it is far more likely to be supported and used through E-RTMP. Especially considering you could make the first video/audio track the normal RTMP compatible tracks and upgrade the other tracks with E-RTMP capable tracks.

Server reconnect/redirect

• Servers can request to connect with another server instead

In our eyes this is one of the cooler features of the specification. When contacting a server to start a push the server can actually redirect the stream to another end point. This has great potential in helping load balancing and is a very good addition to have.

How do I use E-RTMP with MistServer?

Using E-RTMP is quite straightforward and you might've thought about it when you saw the backwards compatibility feature. You simply use RTMP just like before. This means for sending RTMP to MistServer you can select the new features in your other pushing application and simply push towards MistServer using an RTMP url, just make sure the source is set up to push://

• rtmp://mistserveraddress/application/streamname

For pushing out RTMP towards another location simply fill in the RTMP url you've received and MistServer will auto-detect what is and isn't possible. If you're making a selection that is E-RTMP only E-RTMP will be attempted, MistServer supports it both on the input and output side without any need for additional setup.

If you notice your streams are reaching the other side without any of the new features that will mean it's not E-RTMP capable, in that case you might need to fallback to other protocols like SRT, RIST or WebRTC.

MistServer has done a full implementation of the E-RTMP specification, so you'll be able to use all of its features.

What is supported where?

During our testing we've found the following support range, do note that we expect this to not stay up to date as we're sure platforms and applications will adapt. We will try to update this list as we notice changes.

OBS

Multi-track & Codec support

Youtube

Codec support

Twitch

Multi-track support

If you're not sending their exact requested profiles the push is rejected