MCU (Video Conferencing Architecture)
MCU (Multipoint Control Unit) is a video conferencing architecture which supports server-side data processing. Upon gathering primary video streams from all the endpoints, the server separately performs the following actions for each endpoint:
- Combines thumbnail videos of the participants in a single video stream with the layout requested by the endpoint.
- Encodes the video stream up to the quality that meets bandwidth from the MCU to the specific endpoint at the given moment.
- Sends a video stream to the endpoint.
Thus, it is possible to increase the number of conference participants that can be displayed by an endpoint based upon the limits of its equipment and communication channel. Hypothetically, MCU scaling is more efficient than SFU scaling because the user always sends and receives only one thread.
Build a scalable video conferencing architecture with TrueConf Server MCU
Connect SIP/H.323 endpoints, meeting rooms, and corporate users in one secure conferencing environment. Use TrueConf Server as an MCU to host multipoint video meetings, manage participants centrally, and support interoperability with existing video conferencing infrastructure.
But in practice, however, an MCU-based system requires a lot of computing power and does not scale that well, even taking into account possible virtualization scenarios. Besides, it is really expensive to connect new users to such systems, because on average, each new user needs a separate logical core of the server CPU.
Advantages of the MCU Architecture
- Does not require wide bandwidth for the client. Bitrate does not depend on the number of participants, but on the amount of the data sent and received.
- The client connects to the media server, not directly to other participants.
- Server-side recording is available.
- The server sends a single media stream, which allows you to participate in conferences on weak devices (smartphones or tablets).
- Devices using H.323/SIP protocols can participate in conferences.
Disadvantages of the MCU Architecture
- An expensive server is required to mix multiple media streams into one.
- The number of participants in a conference directly depends on the performance of the media server, so in practice, this architecture rarely allows conferences with more than thirty participants.
- The user cannot control the video layout or disable video reception from a specific participant.
- In order to differentiate participants in video layout, each participant’s video is labeled, which might negatively affect video quality.
Load Сomparison for a Сonference with 16 Participants
You can also learn more about other video conferencing architecture types on our website.
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FAQ
How can we overcome the typical 30-participant limit of traditional MCU architectures for large corporate meetings?
Traditional MCUs struggle with scale because mixing video streams is highly resource-intensive, often requiring a dedicated logical CPU core for every new user. To host massive conferences without hitting these hardware limits, you can use TrueConf Server, which utilizes advanced media processing and clusterization to support up to 1,500 participants in a single meeting. This allows enterprises to scale their video infrastructure seamlessly without needing to provision expensive new physical servers for every few dozen users.
Do I need to purchase expensive, dedicated physical hardware to run an MCU for my organization’s video calls?
While traditional MCU setups often require costly, specialized hardware appliances to handle the heavy video mixing load, modern software-defined solutions offer much more flexibility. TrueConf Server can be deployed as a powerful software MCU on your existing standard servers or virtual machines, significantly reducing your capital expenditures. This approach delivers enterprise-grade multipoint conferencing capabilities while maximizing your current IT infrastructure investments.
Can participants customize their video layout or turn off specific video feeds in an MCU-based conference?
In a strict, legacy MCU architecture, the server dictates the final video layout, meaning users typically cannot rearrange tiles or disable individual participant feeds to save bandwidth. However, modern platforms bridge this gap by offering flexible client-side controls alongside efficient server-side processing. With TrueConf, participants enjoy a highly customizable interface where they can adjust layouts, pin specific speakers, and manage their own viewing experience without overloading the central media server.
How do legacy SIP and H.323 conference room systems connect to a modern software-based MCU?
Legacy hardware endpoints rely on standard telephony protocols that require a central server to translate and mix their media streams with modern software clients. TrueConf Server acts as a highly efficient MCU with a built-in multi-gateway, natively supporting both SIP and H.323 protocols out of the box. This allows you to seamlessly invite your existing physical room systems into the same high-quality video conferences as your remote software users, completely protecting your previous hardware investments.
Will an MCU-based architecture work well for employees using older laptops or mobile devices with limited internet bandwidth?
Yes, one of the biggest advantages of an MCU is that it sends only a single, pre-mixed video stream to each participant, which is ideal for devices with weak processors or low bandwidth. TrueConf optimizes this process further by using intelligent adaptive bitrate technology to ensure the stream perfectly matches the user’s current network conditions. This guarantees that even employees on basic smartphones or older laptops can participate in smooth, uninterrupted video meetings.
How does server-side recording work in an MCU environment, and is the data secure?
Because the MCU receives and mixes all individual video streams on the server before sending them out, it can easily capture the final combined layout directly without relying on a participant’s local hardware or internet speed. TrueConf provides robust, secure server-side recording that stores these meeting archives locally within your private infrastructure. This ensures that all sensitive corporate discussions and training sessions are safely archived and accessible only to authorized personnel, completely bypassing the risks of cloud storage.
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