Using an external encoder

Limitations of the in-browser encoder

Modern browsers are incredibly powerful and able to go way beyond browsing the web. We leverage some of this awesome when you stream a webcam event. The video feed from your webcam is encoded right in your browser and streamed to the SlideSync servers without you having to set up anything.

But web browser encoding has many limitations. What if you want to use more than one camera? What if you want a backup stream to protect your event from a network error? What if you’re setting up a multilingual event and need to send two separate audio?

For advanced event production, you’ll need an “external encoder”. SlideSync support external encoders for some subscription tiers. Contact us if you think you need it.

An external encoder is a software that specializes in handling video and audio sources and streaming them to a streaming server, in our case, SlideSync. But you could very well use the same software to stream the same content to YouTube Live just by changing a few settings.

There are many options to choose from when deciding on a good external encoder. Luckily, one of the top encoders out there is free and open source:

Streaming with OBS Studio

Encoders are very advanced programs and you could write a book about all the options. In fact, it’s been done.

Below is a very limited tutorial of how to set up OBS Studio for a basic webcast.

OBS Studio
  1. Preview. What you see here is what your users will get when you hit “Start Stream”.
  2. Scenes. A stream usually involves more than one source. For example, video and sound. A “scene” is a bundle of sources that work together. More on that further down.
  3. Sources: what sources are in that scene.
  4. Mixer: Which microphones are in use right now
  5. Scene transition: if you’ll use more than one scene, a transition effect will be applied when you switch
  6. Main controls

Below is an example of two scenes.

OBS streaming with webcam
My laptop webcam + my laptop internal microphone
OBS streaming with external webcam
A USB conference cam + a table microphone

Note that, in the second example, with the conference camera, there are two microphones available in the mixer. The one from the conference camera and the standalone table microphone.

In this example, we’ll use the conference cam and the table mic. They are likely to give a much better result than internal laptop gear. Internal microphones in particular often offer low-quality sound due to the internal noise of a laptop (fans, hard drives). Encoding is pretty intensive and the fan will likely spin fast.

Step by step tutorial

SlideSync setup

Let’s set up SlideSync for external encoders at first.

SlideSync select encoder
SlideSync RTMP URL and stream key

In Basics > Encoding method, select “Other Encoder”. This will expose the server addresses for SlideSync, as well as the Unique Identifier for this event, called a “Stream” key. When we copy-paste this information into OBS, it will be able to stream content to SlideSync.

SlideSync supports “Backup” streams, where you send your stream twice, using different routes, for redundancy purposes. In this tutorial, we’re only setting up a single stream.

Enter RTMP server and stream key in OBS
This is where you enter the server URL and Stream Key in OBS

And OBS is set up to stream to SlideSync. Now let’s make sure it streams some content.

OBS setup

It’s now only a matter of letting OBS know which sources we want to use. In this case, a conference cam, and a table mic.

Previewing and going live

Now, as soon as you click “Start streaming”, SlideSync will receive the stream and start the preview. The stream is not yet delivered to your attendees, but you’ll be able to preview it and test the setup. Check out the Event Manager Checklist for more details on the Event Preview.

As long as the external encoder is feeding a stream to SlideSync, a “Start Webcast” button will be displayed in the Live Producer. Click it to start delivering the stream to your attendees.