Let’s meet! Web-based Videoconferencing

Overview

Let’s meet! is a video conferencing service hosted by the German Cancer Research Center (DKFZ), built upon the open-source platform eduMEET. This platform provides a sovereign solution for web-based videoconferencing, specifically designed for the research and education community. eduMEET offers a cost-effective and privacy-focused alternative to commercial options. Its ease of use, requiring no client software installation, promotes accessibility for a wide range of users – including researchers, educators, and artists – and supports seamless collaboration, specifically for small‑ to medium‑sized groups.

Key Features

• High-Quality Video: Enjoy clear and detailed video conferencing with support for up to 4K resolution.

• Dual Camera Support: Connect a second video device for versatile presentation options.

• Screen sharing – Stream your desktop, applications, or specific windows with a single click.
• Chat messaging – Text chat support to keep the conversation flowing.
• Interactive whiteboard – Draw, annotate, and brainstorm together on a shared canvas, complete with pen, shapes, and sticky notes.
• Virtual breakout rooms – Split participants into smaller groups for focused discussions, then bring everyone back with a tap.
• Room lock & Waiting lobby – New attendees of locked rooms wait in a host‑controlled lobby; the host receives a notification and can admit or deny entry, ensuring privacy and control.
• Live reactions – Participants can raise their hand without interrupting the speaker.
• Invitation via meeting URL - Copy the link straight from the browser’s address bar!
• Register rooms - Register a room in advance - Create your own virtual room with all the settings configured exactly as you need them — very neat for recurring meetings.

Registering a meeting room

You can register rooms in advance through the resource booking functionality on the cloud portal. This links the room to your account, giving you full ownership and customization options. You can access the resource booking in the landing page as well.

During resource booking, you’ll be prompted to configure your room:

• Naming & Description: Give your room a clear name (lowercase letters, no spaces, permitted characters: a-z, 0-9, -, .) and description.

• Branding: Add a room background to your meeting space by providing publicly accessible URLs to image files (e.g., https://hifis.net/assets/img/jumbotrons/display_2k/markus-spiske-PsRUMc7vilg-unsplash.jpg).

• Controlling Number of Videos: Limit the maximum number of visible participant’s video streams.
• Enabling Features: Toggle options like breakout rooms to suit your meeting needs.
• Room Locking: Secure your room by enabling the lock function, requiring participants to wait in a lobby for admission.

Once you have completed the resource booking process, your personal meeting room is provisioned and ready for use. You can access your room by navigating to https://letsmeet.helmholtz.cloud/ and entering the exact name you chose during the resource booking process. Alternatively, you can directly access your room using the full URL: https://letsmeet.helmholtz.cloud/[your registered room name]. For example, if you registered a room named research-team-meeting, the full URL would be https://letsmeet.helmholtz.cloud/research-team-meeting.

It is also possible to use a room on-the-fly, but only when you are already logged in: Just type a roomname on the landing page and join. There is even the possibilty to claim this room afterwards. In order to do this, go to the settings in the room, then navigate to ‘administration’ and click ‘claim current room’.

Inviting Participants

Once a room is created, you can share the meeting details with participants in two ways:

• Room Name: Simply provide participants with the room name, which they can enter on the Let’s Meet! landing page.

• Direct URL: The easiest method is to copy the URL directly from your browser’s address bar and include it in your invitation email, calendar event, or chat message. This will take participants directly to the meeting.

Joining a Meeting

The Let’s Meet! service is accessed via its home page: https://letsmeet.helmholtz.cloud/.

Landing Page

From here, you can:

• Join as a Participant: Enter a room name and click ‘Join’ to proceed through the media checks.

• Host a Meeting in Your Personal Room: Log in using your Helmholtz ID to host a meeting in a personal room that you have registered in advance. Just choose from the drop-down below ‘MY ROOMS’. Log in is not required to simply join a meeting.

• Copy the meeting link: Click this and have the link to the room in the clipboard. A simple way to share the link.
• Register a room via cloudservice: Use the link at the bottom and access the cloudservice, where you can set up your room. Log in is needed to use this service.

Media Checks

Before entering a meeting, you can adjust the following settings:

• Audio Settings: Select your preferred microphone (audio input) and speaker (audio output). You can test your speaker by clicking the music note symbol - you should hear a short ping. If a microphone is active, you should see a colored vertical bar on the right side while speaking.

• Video Settings: Choose your desired camera (video input). You can also blur your background using the option to the left of the dropdown menu. You could even have a video-background, which is set by clicking the icon between blur-icon and camera name.

• Name: Edit the name that will be displayed to other participants. This can be edited during a meeting.
• Enter the room: Click on ‘Join’.
  • If the room is not locked, you will be admitted immediately.
  • If the room is locked, you will be taken to the lobby. The host will be notified and can let you in.
  • If you are the host of the room, you must be logged in to open the meeting.

Waiting in the Lobby

If the meeting room is locked by the host, you will be placed in a waiting lobby before being admitted. This allows the host to control who joins the meeting.

What happens in the lobby:

• Notification: The host will receive a notification that someone is waiting to join.

• Waiting Screen: You will see a screen indicating that you are waiting for the host to let you in.

• Host Admission: Once the host admits you, you will be connected to the meeting.

Important Notes:

• Room Locking: Hosts use the lobby feature to prevent unwanted participants from joining the meeting directly.

• Host Action Required: You will not be able to enter the meeting until the host grants you access.

• If You are the Host: Ensure you are logged in to unlock and open the meeting for participants.

In the meeting

• Main View: Shows your video and of other participants, if applicable. A silhouette is shown for participants with deactivated camera. In case of a shared screen, all videos will appear stacked on the right side.

• Menu bar: At the bottom of the screen, you will find a menu bar with various options:

  • Audio: Here you can mute or unmute your microphone. The purple icon lets you change the microphone, if multiple are available.
  • Video: Activate / deactivate camera. Clicking the purple icon allows you to choose a camera, if there are multiple, and background-blur can be activated / deactivated.
  • Share: Share your screen, a window, or a browser tab. You might even share audio from a tab. Note: this can be done by multiple participants simultaniously
  • Raise Hand: You want to raise attention? Raise a hand! But please don’t forget to lower it afterwards. If several people raised hands, they will appear sorted in the order of raising hand (oldest at the top, newest at the bottom).

  • Reactions: Reactions are accessible via the small purple icon upon the ‘raise hand’ button. They disappear after a couple seconds.

    • Smiley: simply :)
    • Firework: in case confetti is needed.
    • Applause: clap your hands.
    • Thumbs up: signal approval.

  • Show Participants: A list of participants will appear on the right side of the window. Here you can change your name, vote for ending the meeting and kick others out (only if this is your room).

  • Show Chat: Chat messages are shown on the right side, below the list of participants, if also activated. Write messages by typing and clicking the triangle on bottom-right - or simply press enter. Messages have the name of the author and a timestamp attached. Clicking ‘CLEAR CHAT’ does exactly what it promisses.

  • Three-dot menu: There are more features accessible via this button:

    • Start video: You can share the video of an additional camera. To do so, press ‘Start video’. Pick the additional camera from the dropdown and confirm with ‘ADD NEW VIDEO INPUT’. Stop sharing with the ‘Stop video’ button, that appears at the middle on the right side of your shared video. Blurring is applied there too, if activated for the main wecam and ‘Enable background effects on extra video’ is set.

    • Share file: This is not active.

    • Start local recording: Click there and pick a target file. After that, you have to select what you want to record. This could be a tab, a window or even an entire screen. A dot on the top indicates recording. To stop the recording, go to the three-dot button and click ‘Stop local recording’. The file is stored as mp4.
    • Start drawing: A simple drawing app is included. All participants can contribute to a canvas. You can drag the canvas (hand), use a pencil, type text, zoom in and out, change colors, change background, un-do and re-do, trash the canvas and download as png, jpeg or svg.
    • Side View (Show Participants): On an activated sideview all participants are displayed. It shows for every participant, whether camera and microphone are activated.
      • Close Meeting for All: Click this and close the meeting for all. You have to confirm this.

  • Mute All: Mute all participants, including yourself.

  • Stop All Video: Stop all videos, including yours.
  • Stop All Screen Sharing: Whoever is sharing, this will bring an end to it.
  • Countdown timer: Here you can set a timer by typing a duration directly (HHss) or via dropdown (clock icon). Start the timer and everybody will hear a ping when time is up. Timer can be paused by clicking ‘pause’. Reset the timer by clicking ‘x’.
  • Adjust Volume: You can adjust sound volume from all participants with activated microphone.
  • Change Displayed Name: You can edit your displayed name, even if you already joined.

  • Break-out Rooms: Break-out rooms are handy in a webinar scenario - groups of people can discuss in these rooms and return later to the main room.

    • Creation: Break-out rooms can be created by typing a name in the textfield ‘Breakout room name’ and clicking the icon on the right side.

    • How to join: After a room is created, members of the main room can be moved to the break-out room via drag’n drop by the room owner. The room owner can join a break-out room via ‘JOIN’.

    • How to leave: You can return to the main room by pressing ‘LEAVE’ (only room owner), or an administrator removes you from this room via ‘CLEAR OUT’ (room keeps existing, but everybody is removed back to the main room) or via ‘REMOVE’ (room gets removed, all return to main room). You can move participants to rooms by drag’n drop, but only as room owner. As a simple participant, you can leave the main room, but not just the break-out room. So an administrator has to dispatch normal participants to break-out rooms.

• Side View (Messages): A subsection of the sideview displays a message-window, when the button with the speech bubble is clicked.

  • Messaging: A simple message window, write and read messages.

• Enter / leave fullscreen (top right): Self-explaining.

• Show settings (top right): Here you will find the settings.

  • Media: Here you can access settings, that were already available at the landing page. You can configure your input/output device for audio, set output for video. Blur your background, set a background for your video, or just test your devices.

  • Appearance: This part of the settings allows you to select the language. There are quite some translations, but be aware that labels without translation stay in english. The next section is about visible participants. A slider can be used to have 2, 4, 9, 25 or 49 concurrent videos. Set a limit here, if you encounter choppiness during a meeting. Below that, you can select a background picture by clicking ‘SELECT BACKGROUND’. Here you can upload an image. The remainder of this tab consists of following flags:

    • Mirror view of own video - not mirrored for other participants.

    • Hide self view video - don’t see your own video, but others still do.

    • Hide participants with no video - don’t even show a silhouette.
    • Notification sounds - hear when someone is raising a hand, or just see it.
    • Vertically stacked side panels - have videos placed horizontally below the shared screen - or vertically on the right side.
    • Uncrop my video - has little to no effect.
    • Enable background effects on extra video

  • Advanced:

    • Audio settings:

      • Select the audio preset: This contains two presets - Conference audio and HiFi streaming. Conference audio has some correctional settings, that are useful during meetings. HiFi streaming keeps the sound mainly unaltered.

      • Echo cancellation: Reduce echo during meetings. Not so urgent when using a headset.

      • Auto gain control: Keeps the output signal level consistent, even if there are variations in the input signal.
      • Noise suppression: Others can understand you better in a noisy environment, when this is activated. Activate ‘Noise suppression’ and set the slider near -100 dB -> noise reduced, but robotic sound. Set near zero -> no noise reduction. Current decibel values are displayed on the slider to indicate the noise-level.
      • Audio sample rate: A higher value allows to capture higher frequencies. With 44.1 kHz sampling rate, all frequencies the human ear can detect are covered. 48 kHz allows the use of anti-aliasing during post-production.
      • Audio channel count: Set to 1 (mono) or 2 (stereo).
      • Audio sample size: Values range between 8 and 32 bit. Details are a bit complex, but it relates to dynamic range, which is the difference between lowest and highest recorded volume.
      • Enable Opus Discontinuous Transmission (DTX): Feature of the Opus audio codec that reduces the bitrate during periods of silence by not transmitting audio frames, which helps save bandwidth.
      • Enable Opus Forward Error Correction: A method to improve quality by allowing the receiver to recover lost packets using redundant data sent in previous packets.
      • Select the Opus frame size: Values between 3 and 60 ms can be set, with smaller frame sizes generally reducing latency but may require more processing power. For most applications, a frame size of 20 ms is recommended, as it balances low latency with good audio quality.

    • Video settings:

      • Select your video resolution: possible values are

        • Low
        • Medium
        • High (HD)
        • Very high (FHD)
        • Ultra - beware! This will show your own video as portrait, but others will see your video as a smaller section, when ‘Uncrop my video’ as active (see ‘Appearance’).

      • Select your webcam frame rate

        • Values range from 1 to 60.
      • Select your screen sharing frame rate
        • Same as above, but for screensharing. If you have a lot of movement on your shared screen, choose a higher value.

      • Select your preferred video mime type

        • video/webm - with combinations of video- and audio codec. (e.g. ‘video/webm;codecs=”vp8, opus”’ -> use WebM container with VP8 videoencoding and Opus audioencoding)
        • video/mp4
        • video/x-matroska;codecs=avc1

  • Management!:

    • To access the management functionalities, you need to login via Helmholtz ID first. Normal users do not need to login to participate in a meeting, but if you want advanced control over a room, you must be logged in.

    • Login: As a normal user, you can log in via Helmholtz ID by clicking ‘Log in’. You will be redirected to the log in page of your homeorganisation. After successful authentication, you are redirected to the management client.

    • Edit Current Room: This allows you to change settings.

      • Name - can’t be changed

      • Description - describe the room

      • Default Role - here you can choose, which role should be applied by default:

        • Participant - no special rights
        • Moderator - very wide-ranging permissions
        • Bypass room lock - no permissions at all

      • Logo - provide the address of a picture, that is accessible from the internet. It will appear on the top left.

      • Room background - choose a picture, set it as background.
      • Maximum active videos - limit the maximum number of visible participant’s video streams.
      • Lock room - lock the room
      • Enable chat - allow chat
      • Enable raise hand - allow to raise hand
      • Enable reactions - allow reactions
      • Enabled filesharing - filesharing is not active, no matter what is set here.
      • Enable local recording - you can allow to record a meeting.
      • Enable breakout rooms - allow to have breakout rooms. * Advanced management settings: If you are logged in and the room is yours, then you can use this link and access the management client. Here you have the possibility to use ‘TENANT LOGIN’ and you have then the option to list your rooms, list users (only users that you already know by email address, everybody else has just an id displayed) and view role definitions.

      • Rooms: Your rooms are listed here. Many settings can be set already via ‘EDIT CURRENT ROOM’, but here you have the possibility to set additional room owners and room-user roles.

        • Room owners: Click ‘ADD ITEM’ to add a user as room owner. You should search for user via email address, or you know their id. By default, you only get displayed email adresses from users you already searched and found.

        • Room-user roles: By clicking ‘ADD ITEM’ you can appoint users to roles within a certain room. Possible are pre-defined roles - ‘Participant’, ‘Moderator’ and ‘Bypass room lock’ - that have different permissions. Basically the hierarchy is ‘Owner’, ‘Moderator’, ‘Participant’ and ‘Bypass room lock’, with ‘owner’ having the most permissions. See below for details. This is helpful when you know in advance, who will regularly attend to the room. Everybody else will get the default role.

      • Users: Users are listed here, but as a normal user, you don’t see much more than the id and the tenant. Let’s assume that you already searched for a user via email address - then you get the address displayed aswell.

      • Roles: Roles are not editable, but you can still see, which permissions are applied to the roles. For example ‘Moderator’ has permission to un-lock the room, but user with role ‘Participant’ are not allowed to do that. Permissions are not described here in detail, but the names are mainly self-explanatory. For instance ‘SEND_CHAT’ allows the use of the chat.

• Lock or unlock room (top right): Open a closed room, or do the opposite. An open room can be attended by everyone.

• Log out / Log in: Log out by clicking there. Be aware that you don’t leave the current room. You can use the same button to log in.

• Timer (Display): Here you can see, how long the current meeting is already going. The clock starts with the first participant.

• Timer (Countdown): Click here and the side-view will open. There you can set and start a countdown timer. A short ping will indicate when time is up.

• Leave: With this button you can leave a meeting. You will be asked, whether you want just leave (NO / YES), or even close the meeting for all - but this has to be confirmed again.

• Help: In the left bottom corner is a question mark. Press this to get a list and description of available hotkeys.

  • M: Mute audio
  • V: Stop video
  • R: Raise hand
  • S: open settings
  • D: Filesharing
  • L: Lock room
  • P: Show participants
  • C: Show chat
  • Q: Show stats
  • SPACE: Use Push-to-Talk

  Every feature here was already described before, except ‘Q - Show stats’. This shows WebRTC media statistics. Here you can check resolution, frame-rate, bit-rate and round-trip time of several audio- and video streams by clicking ‘Q’. More details can be found here: .

FAQ & Troubleshooting

• Refreshing the browser cache can help sometimes (Shift + reload)