Video conferences require a fast and stable internet connection to work well. A lot of data has to be transmitted without loss in a very short time. The requirements are therefore higher than for video streaming, for example. The time between sending and receiving (=latency) should therefore be as short as possible.

Connection via LAN vs. WLAN

If possible, use access via LAN cable. This allows you to utilise the maximum available transmission speed.

The transmission quality can be significantly impaired in WLAN, e.g. by a single wall between your device and the router or by the general distance.

Internet connection speed

The broadband connections for private customers have different speeds for uploading (data you send) and downloading (data you receive).

Required data rates for video conferences:

1. Audio transmission: approx. 80 kbit/s each for upload and download
2. Video transmission: per activated camera approx. 200 kbit/s at medium quality (standard selection)
3. Screen sharing: usually 1 Mbit/s or more

Example calculation for four participants

Scenario: All four participants use video and screen sharing.

• Presenter: 1 MBit/s + 200 kBit/s + 80 kBit/s = 1280 kBit/s upload and 3*200 kBit/s + 80 kBit/s = 680 kBit/s download
• Three other participants: 280 kBit/s upload and 1680 kBit/s download

With a DSL 16,000 connection, a presentation cannot be carried out without disruption. The associated upload data rate of approx. 1,000 kbit/s is too low. Screen sharing, camera video and sound have to share the insufficient data rate. Not all the necessary audio data can be sent from the presenter to the BigBlueButton server in time. As a result, the video will jerk and the sound will drop out for the other participants

What can you do?

1. Make sure that no one else is using your internet connection at the same time. This is because the bandwidth is shared between all participants/devices.
2. Only activate screen sharing in exceptional cases. Upload the presentations directly to the BigBlueButton.
3. Enable video only for the person presenting.
4. Disable your video as long as you are not presenting.
5. Use telephone dialling if necessary.
6. You could test the speed of your internet connection with the speed test from Chemnitz University of Technology.
7. BigBlueButton can also be used via mobile phone, provided you have enough data volume. The speed of LTE (4G) is usually sufficient for this.

Videos have to be encoded and decoded. This requires a lot of computing power.

This applies to camera and screen sharing. Each shared camera in the meeting is transmitted as a single video. Consequently, your computer also has to decode this many videos and simultaneously collect the audio data from your microphone, compress it and send it to the server via the broadband connection.

What can you do?

1. Watch the CPU utilisation (Windows: Task Manager; MacOS: Activity Monitor)
2. Set the time for installing Windows updates to outside
3. Stop other programs during the conference
4. Close other browser tabs (e.g. pages with lots of advertising or browser games)

• Use headset or headphones > possible feedback and annoying background noise are avoided
• Levelling the microphone well (not overdriven)
• Place laptop with fan on a soft surface to reduce vibrations (caution: do not cover any ventilation slots)