​Multi-Stream Transport (MST) in DisplayPort

Feb 16th 2022

​Multi-Stream Transport (MST) in DisplayPort

Having multiple displays is something very common in this remote work era. According to a John Peddie Research study from 2017, people that work with various displays are 42% more productive. This trend only continues to rise, and that’s why you can see in many videos or setups for incremental productivity using multiple displays.

Multi-display lets you divide your tasks to work while keeping in touch in a Zoom call and even having a chrome tab running video. That’s not all; even for gaming and home theater purposes, it's useful for extending displays and providing you with a better experience.

Although this technology is already pretty common today, these setups work in Multi-Stream Transport (MST). Without it, many display setups are trickier and usually more expensive and inefficient.

So, if you want to run multiple monitors, such as a dual monitor or triple monitor setup, and use neat features like video wall mode, you will need to know what MST is, the different methods of MST, and see if your computer or OS is compatible.

What is Multi-Stream Transport (MST)?

First introduced in the DisplayPort 1.2 standard, Multi-Stream Transport allows multiple displays connected to a single DP port on a desktop or laptop PC. It does this by combining multiple video signals into a single stream (a process known as multiplexing) and sending it over a DisplayPort cable to a device that disaggregates the signal. The "unbundling" device can be an MST Hub or a series of "chained" MST monitors.

2009 was the year that introduced DisplayPort 1.2 and due to shrinking devices, it was challenging to keep devices able to run multiple setups without some drawbacks. It was most unfair for low spec computers that couldn't afford more specialized GPU units that allowed them to have multiple video outputs (Keep in mind this was another era).

An answer to this issue became an opportunity for the Video Electronics Standards Association to develop MST technology.

There are two types of system configurations available to use the MST; Daisy Chaining and DisplayPort MST Hubs:

Daisy Chaining

Daisy Chaining needs monitors with a DisplayPort, and the main one supports the 1.2 version. The main monitor needs to be connected to the GPU, APU, or iGPU to receive the video signal. Then from the monitor itself, you connect Display cables to other monitors, creating a chain.

The biggest benefit is that there’s not too much wiring. The con is that monitors have to be daisy-chain compatible except the last one.

DisplayPort MST Hubs

The other method is MST Hubs. This hub splits one DP cable into multiple video outputs, both DP or other formats.

One of the biggest benefits of Hubs is that the main monitor is the only one that has to be DP 1.2 compatible. After the DP splits, you can connect older video outputs such as DVI, VGA, or options like HDMI. You will need to have a DisplayPort adapter for these cases.

This DisplayPort makes Hubs more flexible if not all of your monitors feature DP compatibility. The drawback is that these can be pricey, and it's a cost that you sum up on top of monitors and compatible GPUs.

For example, if you have a 4K laptop with DP ports and want to turn it on a Desktop setup, using a DP Hub will allow you to set your monitors with just one simple device.

MST vs. SST Transport Modes

Single Stream Transport mode can only handle one downstream device. This option means the connection between the video output to one single monitor. So to have multiple monitors set up, you need to connect the other monitors to different video outputs.

An example. One GPU with three HDMI outputs can handle three monitors connected from Single Stream Transport Mode.

For MST, you can think of Multi Streams as video data streams that are time-multiplexed. Each virtual channel can target a different monitor downstream from the source.

This mode makes it possible from one video output to send multiple signals to all monitors. Therefore, you can set up dual monitors and even five monitors installations with one output.

Which Operating Systems Support MST?

MST is compatible with Windows 11, 10, 8.1, 8, and 7. Mac OS X is not supported with Chrome OS, although rumors suggest the feature will become available soon.

Mac OS X doesn't support MST with the technologies for display used in macOS computers vs. Windows computers. Mac utilizes Single Stream Transport (SST). While Windows allows for Multi-Stream Transport (MST) on most devices, your limitations are more hardware-related than issues with your OS.

DisplayPort MST Hub Display Modes

The DisplayPort MST Hub offers multiple display modes including:

MST Mirror Mode

Also called cloning or mirroring your screen, mirroring mode will display the same image on each monitor. Screen mirroring is useful in establishments such as retail environments.

MST Extended Mode

Extending your display allows you to display your PC's desktop on all connected monitors while having a different window open on each monitor. The monitors still function as separate screens, but your usable workspace gets extended, and you can easily multitask and even move objects from one screen to another.

MST Video Wall Mode

Creating a video wall allows you to combine all the monitors in your setup to act as one giant monitor. You can arrange the monitors however you want them: vertically, horizontally, or grouped.

Multi-stream wall mode lets you experience an amazing widescreen gaming experience, creates a perfect space for running 4k Blu-ray movies for a home theater PC setup, and also in productivity, it’s huge for distance and makes multitasking easier. It has endless possibilities.

Ultimately, you need to understand the possibilities of Multi-Stream Transport (MST) before jumping into creating your own productivity home office or gaming station.

MST display modes adapt to many situations, from productivity home office and gaming to commercial settings and big displays in malls.

Despite many possibilities that DP brings to the table, it's still important to keep in mind to consider your hardware equipment needs.

For example, to have a dual monitor setup, you can get away with internal GPU from the CPU. It's not the same if you aim to have a gaming setup with 4k monitors at 60hz. You need to consider buying more powerful equipment and even monitors and hubs with DisplayPort 1.4 or 2.0 compatibility.