Simulcast Definition: The Tech Behind Efficient Meetings

Media and its transmission have undergone significant transformation in recent years. Just a few decades ago, it was almost unimaginable that people could launch their own media channels and broadcast it across a wide audience.

Suppose you want to start a broadcast, but your viewers are using different platforms. Would you really have to make a choice between TikTok vs YouTube, Instagram vs TikTok, etc?  Not at all! Simulcast streaming technology allows you to run a simultaneous live broadcast for different applications from the same platform. Let’s clarify what this means.

What is simulcasting?

Simulcast is the synchronous broadcasting of programs or events through multiple services using real-time messaging protocol (RTMP). For example, broadcasting a soccer match simultaneously on TV and radio is a simulcast.

The term simulcast came from America when NBC and CBS began broadcasting several programs simultaneously on both radio and TV in 1948. Today’s simulcast refers to content that is shared digitally through websites and social platforms. Virtual events, webinars, speeches, sporting events, or content created for entertainment purposes can be streamed simultaneously to multiple platforms. For the simulcast system, special repeaters are installed that allow the system to operate stably over long distances.

Simulcast is a video conferencing architecture with the following data transmission procedure between the server and the endpoints:

  1. The server receives several (3-5) video streams from each client containing the camera image in various resolutions and quality.
  2. The server sends a video stream copy of the other participants that corresponds to the bandwidth and device capabilities of each endpoint.

How does a simulcast work?

Simulcast Definition: The Tech Behind Efficient Meetings 1

This architecture is a good choice when the layout puts one participant in the bigger video window, while others are displayed in smaller panes.

Simulcast Definition: The Tech Behind Efficient Meetings 2

Simulcast architecture advantages

  • Several levels of quality allow for some flexibility as compared to earlier VC architectures.
  • Saves the server from processing  video.

Simulcast  architecture disadvantages

  • In real life Simulcast rarely manages to use channels and resources efficiently because the image in all streams is transmitted the same, simply with different levels of detail. Redundancy occurs because each participant in the conference sends a larger stream than necessary.
  • Simulcast-based systems require significant resources from user’s VC endpoints, but use them inefficiently. In such systems the main network load falls on the endpoints, which is caused by the need for simultaneous support of multiple levels of video quality.

Comparison: 4 participants, on the endpoint

MCU SFU Simulcast SVC
Outgoing streams 1 1 3 1
Incoming streams 1 3 3 3
Out channel, Mb/s 1,0 1,0 1,5 1,2
Incoming channel, Mb/s 1,0 3,0 1,0 1,0
CPU load 20% 60% 80% 30%

Comparison: 4 participants, on the server

MCU SFU Simulcast SVC
Outgoing streams 4 12 12 12
Incoming streams 1 4 12 4
Out channel, Mb/s 4,0 12,0 ~4,0 ~4,0
Incoming channel, Mb/s 4,0 4,0 6,0 4,8
CPU load 100% 0% 0% 0%

Simulcast has been replaced by SVC architecture, which allows changing video quality without creating explicit copies.

What is the difference between simulcasting and multicasting?

Simply put, both of these systems transmit the same signal simultaneously from different sites, but simulcast does so on the same frequency and multicast on different frequencies.

Simulcast Multicast
The same frequency for transmitting the same signal Different frequencies for transmitting the same signal
A high level of signal control required  No signal control requirements 
Ease of roaming Roaming requires special settings
Requires complex system failure scenarios planning No requirements
Frequency efficient Frequency consuming
Requires the same number of repeaters at each site Ability to use multiple repeaters at each site
Requires voting Does not require voting

Simulcast and multicast can be combined to cover an area with high population density, high number of users and channels, and for areas with low population density and subsequent limited channel demand.

What to consider when selecting a simulcast platform

Experts call streaming the media of the future. According to recent surveys, 63% of millennials watch streaming, which is the largest target audience on the Internet. At the same time, popular streaming platforms are firmly integrated into the digital toolkit, and the markets for eSports and video game streaming are constantly in the spotlight of the media. 

Live streaming is becoming more and more popular not only among bloggers and streamers, but also among ordinary users. Today there are many free platforms with this feature, such as YouTube Live, Facebook Live, Periscope, and Instagram Live, but they are all primarily focused on B2C (consumers), not B2B (businesses).

For example, live broadcasts are becoming a must-have tool in Internet marketing because they bring brands closer to customers, and live broadcasts increase customer loyalty to products and services.

If you are a business owner or IT expert and you would like to use video for streaming webinars, all-hands meetings, remote learning or training sessions, TrueConf is the perfect solution to gain the attention of wide audiences and at the same time keep your media secure. This solution allows you to use video as an effective marketing tool in your company’s corporate identity without compromising security.