use_broadcast: Broadcast Your Slides
In xaringanExtra: Extras and Extensions for 'xaringan' Slides

use_broadcast

R Documentation

Broadcast Your Slides

Description

Experimental! Broadcast lets others follow along, in real time! Built with PeerJS, broadcast give you a unique URL to share with your viewers. Then, when they load your slides, their slides will automatically follow you as you present!

Usage

use_broadcast()

Details

To equip your slides with broadcast capabilities, add the following chunk to your slides’ .Rmd file.

```{r broadcast, echo=FALSE}
xaringanExtra::use_broadcast()
```

Then, host your slides online, either on a personal webpage, or through Netlify, GitHub Pages, GitLab Pages, or another service.

When you want to present, open the version of your slides hosted online in a modern browser. Then press P to enter the presenter view. Click on the Broadcast button to start broadcasting.

After a short moment, if everything works, the broadcast button will turn into a broadcast link. Share this link with your audience. When they open the link, their browser will connect with yours and from then on, whenever you advance or change slides, your viewer’s slides will move to the current slide.

Note that the broadcast link is unique and, as the presenter, is remembered for 4 hours. After 4 hours of inactivity, a new link will be generated. In general, create and share the broadcast link just before or as your event starts and certainly not more than an hour before the presentation.

How It Works

PeerJS creates a direct, peer-to-peer connection between your browser and your viewer’s browsers. A third party PeerJS server is used to initially facilitate the connection using the broadcast ID to connect with the presenter’s browser.

After the connection is made, data is sent directly between browsers and the PeerJS server is no longer involved. Furthermore, at no time is any information about your presentation transmitted over the network. When you move to a slide, say for example slide 11, broadcast announces “Slide 11” to any connected viewers and JavaScript in their browser moves their presentation to slide 11.

This has two consequences:

Viewers can move around and look at slides other than the one currently active in the presenter’s browser. When the presenter changes slides, however, all viewers’ slides will move to the new slide.
If your slides involve interactivity, such as htmlwidgets or panelset, changes made in the presenter’s view aren’t replicated for viewers. Viewers will be taken to the same slide as the presenter, but they will need to click on their own to follow interactively.

Extra Details

It’s worth mentioning a few details. First of all, the broadcaster needs to be connected first before viewers connect. If a viewer connects before the broadcaster starts (or restarts), they should reload the link to reconnect.

Similarly, if the broadcaster reloads their slides, viewers will also need to reload to reconnect. But once everyone is connected, a message will appear for the viewer to prompt them to reconnect.

If you are the presenter and you load the broadcast link, the broadcast will automatically reconnect and start broadcasting. If you want to view your slides without broadcasting, just load the plain URL for the slides without the ?broadcast=... portion. From this view, you can restart the broadcast from the presenter view and if the broadcast ID is still valid that ID will be used. To reset the broadcast ID without waiting 4 hours, load your slides with ?broadcast=1 and new broadcast link will be created at the next broadcast.