Our recent Remote control feature set for Larix Broadcaster in Larix Tuner provides a great set of capabilities for remote production teams. This article shows how this can be set and used. However, when you work in remote contribution scenarios, you need to see the live stream content with minimum delay. This allows reacting properly to any changes on site.
Thus we used our experience in real-time streaming and added video preview in Larix Tuner.
Video preview utilizes WebRTC technology for real-time streaming the content from your mobile device directly to your producer’s browser window besides the main output stream. The preview stream is not processed or stored anywhere in our facilities, it literally goes glass-to-glass only.
Notice that you need to upgrade Larix Broadcaster instances on your operators’ devices in order to be able to use video preview. Do it via AppStore and Google Play as usual. If your device or Larix’ version does not support preview, the respective window will not be shown.
Here’s how you can use the preview.
WebRTC preview workflow
The producer opens the remote control page where they can operate the video preview.
Here you can click on Preview button to start the preview process without any other setup by default. Notice that the browser will request permissions to access microphone first. This happens not because we need the microphone audio but it’s the browser’s requirement. Please check Network discovery selection section below for more details about that.
Once the Preview button is clicked, the browser and Larix Broadcaster instance exchange the data required to establish connection between the browser and the Broadcaster instance. This may take a few seconds depending on your network environment and the connection settings (see Network discovery selection below).
Once the communication is established, Larix Broadcaster starts sending the preview feed with video and audio directly to the browser.
The delay is just a portion of a second. This is possible only because we utilize WebRTC technology on both ends of this delivery couple, with no extra servers between them.
You can stop the preview by clicking on square button, adjust the volume and expand the browser to full screen.
You may apply any settings to Larix instance, like camera selection, mute, zoom and operate the overlays, and all these actions will be applied to your preview as soon as the device syncs up with Tuner. Here we enable the logo and then see it on the screen.
If your device is located near your speakers, we suggest lowering the volume in the preview player: the delay is really low and it might fire up the unpleasant echo audio effect is you make any noise.
And of course, you may start your main stream any time and operate it as usual. The preview will not affect your streaming process and can be enabled and disabled any time during your work.
You may also tune the preview process using some additional settings that we provide.
Additional settings
There are also additional settings that you can use to tune the preview streaming process a bit. Just click on Show preview settings to see them.
These settings are:
- Network discovery selection
- Content mode
- Preview resolution
- Preview bitrate
Network discovery selection
The default “All networks” mode means that the browser will scan all available network interfaces and request the remote STUN servers to find the best network route to the device. This requires explicit user permission for which the browser makes a microphone access request to the user. There’s no specific permission to scan network interfaces in browsers because it would confuse users about the intention of the WebRTC connection.
The “Local networks only” mode means that the browser will scan all available network interfaces and will not use the remote STUN servers. That is, the connection will be made only inside the local network. Use this option if your browser and your device are on the same network. This option can shorten the connection time. This option also requires user’s explicit permission to access the microphone.
The “External networks only” mode means that the browser will use the default network interface to request the remote STUN servers and won’t scan local network interfaces. That is, the connection will be made through the local network’s gateway. If your browser and your device operate on the same network that will cause unnecessary round-trip of data. This option doesn’t require any user microphone explicit permission.
Please refer to this document for details.
Content mode
By default, Larix Broadcaster will send preview with video and audio component, so you can see and hear the same as your operator’s device. However, you can select video-only or audio-only modes in case you don’t want to clutter your dashboard experience, or in case you want to save additional bandwidth.
Content resolution and bitrate
Proper resolution and bitrate can be selected in order to reduce the bandwidth required to see the preview content. By default, video preview is generated and delivered with 640х360 resolution. You can select any other one but that will require more bandwidth. If you don’t specify the bandwidth then the device will make its bitrate match the resolution.
With preview feature, you may control your remote devices much better. If you have any ideas or suggestions about any remote control features, please don’t hesitate to let us know.