[ram_rar]

Great to see Elixir gaining traction in mission-critical broadcast systems! I wonder, how much of Cyanview's reliability comes from Elixir specifically versus just good implementation of MQTT? and is there any specific Elixir features were essential that couldn't be replicated in other languages?

[ghislainle]

Main developer here.

We use MQTT a lot, it is really a central piece of our architecture, but Elixir brings a lot of benefits regarding the handling of many processes which are often loosely coupled. The BEAM and OTP offer a sane approach to concurrency and Elixir is a nice language on top. Here is what I find the most important benefits:

- good process isolation, even the heap is per process. This allows us to have robust and mature code running along more experimental features without the fear of everything going down. And you still have easy communication between processes

- supervision tree allows easy process management. I also created a special supervisor with different restart strategies. The language allows this and then, it integrates as any other supervisor. With network connections being broken and later reconnected, the resilience of our system is tested regularly, like a physical chaos monkey

- the immutability as implemented by the BEAM greatly simplifies how to write concurrent code. Inside a process, you don't need to worry about the data changing under you, no other process can change your state. So no more mutex/critical sections (or very little need). You can still have deadlock though, so it is not a silver bullet

[somethingsome]

Hey it's nice to see a very successful business in Belgium in this space!

I work at the university and we build acquisition systems with exotic cameras and screens, do you think we could meet one time to discuss possible (commercial and research) projects ?

[dist-epoch]

Have you looked at stuff like NATS/Jetstream instead of raw MQTT?

[davidbou]

MQTT is used for messaging between processes on the embedded device itself, which can be the remote control panel, or a camera node. The panel itself is driven by a microcontroller which gets all the parameters to display and request changes through MQTT. If the camera is controlled locally, like on a LAN, then another process picks up the action and handles the communication with the camera. If the camera is remote (over cellular for example), we don't rely on the bridging functionality that some MQTT brokers provide but rather use Elixir sockets to send the data over. Typically parameter changes would be sent towards the camera and new status would be populated back to everyone. In most cases it's been a single control room, sometimes 2 at different locations, and one camera site so the needs for a wide distributed architecture hasn't been felt yet.

One of the next steps would be to have a real cloud portal where we could remotely access cameras, manage and shade them from the portal itself. In this context we have been advised to look at NATS. Remote production or REMI is now getting more traction and some of our clients handle 60+ games at the same time from a central location. That definitely creates new challenges as centralizing everything for control is a need but keeping distributed processes and hardware is key to keep the whole system up if one part fails.

[travisgriggs]

Which MQTT library are you using? Did you roll your own?

[travisgriggs]

I ask because we’ve taken up Elixir and we use MQTT (also with a custom RPC on top) to coordinate ag irrigation. But I’ve been very frustrated with the state of MQTT implementations on Elixir (or lack of good documentation). I’m wondering if I’ve just missed an obvious one. We currently use a fork of Tortoise, but it has some issues.

Feel free to contact me, details in profile.

[ghislainle]

We also use a fork of Tortoise, wrapped in some easier to integrate code (for our use case).

At first, we used an erlang lib emqtt, but it was left unmaintained and then removed from github. We had to switch to something else. Not completely happy, but it works for us

[joehosteny]

Which version of emqtt are you referring to? We are successfully using 1.11.0 (with AWS IoT Core), which I believe is the "blessed" version for elixir.

[ghislainle]

I do not remember all the details, but I think it was during the transition from MQTT 3.1 to 5.0. We only use 3.1 and the 5.0 code was not yet finished, emqtt had a hard coded a dependency with an old lib, which we wanted to upgrade. There were no hex package, it was pulled from github. And then the repo on github disappeared (or maybe moved?)

I will have a look at this new package, it looks promising

[jerf]

This is Elixir/Erlang/BEAM's core use case, the thing it was designed to do, coordinating and routing with failover and fallbacks a large number of realtime feeds. The original use case was phone calls, but other than the fact these video streams are much much larger per second, most of the principles carry over.

As much as I am a critic of the system, if this is your use case, this is out-of-the-box a very strong foundation for what you need to get done.

[davidbou]

Yes, this was one of our initial considerations when we first started, and the telecom analogy of the original Erlang development application was one of the main reasons we took this approach. Now, we only "stream" metadata, control data, and status. Even though we manage video pipelines and color correctors, the video stream itself is always handled separately.

For anyone interested in the video stream itself, here's a summary. On-site, everything is still SDI (HD-SDI, 3G-SDI, or 12G-SDI), which is a serial stream ranging from 1.5Gbps (HD) to 12Gbps (UHD) over coax or fiber, with no delay. Wireless transmission is typically managed via COFDM with ultra-low latency H.264/H.265 encoders/decoders, achieving less than 20ms glass-to-glass latency and converting from/to SDI at both ends, making it seamless.

SMPTE 2110 is gaining traction as a new standard for transmitting SDI data over IP, uncompressed, with timing comparable to SDI, except that video and audio are transmitted as separate independent streams. To work with HD, you need at least 10G network ports, and for UHD, 25G is required. Currently, only a few companies can handle this using off-the-shelf IT servers.

Anything streamed over the public internet is compressed below 10 Mbps and comes with multiple seconds of latency. Most cameras output SDI, though some now offer direct streaming. However, SDI is still widely used at the end of the chain for integration with video mixers, replay servers, and other production equipment.

[jerf]

I was tempted to go into the fact that the video streams wouldn't pass through BEAM, because that would be crazy, but I cut it out.

AIUI, technically, the old phone switches worked the same way. BEAM handled all the metadata and directed the hardware that handled the phone call data itself, rather than the phone call data directly passing through BEAM. In 2025 it would be perfectly reasonable to handle the amount of data those switches dealt with in 2000 through BEAM, but even in 2025, and even with voice data, if you want to maximize your performance for modern times you'd still want actual voice data to be handled similarly to how you handle your video streams, for latency reliability reasons. By great effort and the work of tons of smart people, the latency sensitivity of speech data is somewhat less than it used to be, but one still does not want to "spend" your latency budget carelessly, and BEAM itself is only best-effort soft realtime.

[zaik]

> couldn't be replicated in other languages?

All programming languages can do any task. It's about how easy they make that task for you.

[zwnow]

Yea and with that i'd think it would be a pain in the ass trying to replicate BEAM behavior in different langs

[thibaut_barrere]

This is true in general but only until it gets false.

For instance, Elixir supports compilation targeting GPUs (within exactly the same language, not a fork).

Most languages do not allow that (and for most it would be fairly hard to implement).

[goatlover]

For any finite, computable task, as long as the language has access to the hardware that can perform the task in practical time, assuming the language doesn't present any compilation or memory issues to take advantage of said hardware in practical time for the task to be worth computing.

[dorian-graph]

> and is there any specific Elixir features were essential that couldn't be replicated in other languages?

From the article:

> “Yes. We’ve seen what the Erlang VM can do, and it has been very well-suited to our needs. You don’t appreciate all the things Elixir offers out of the box until you have to try to implement them yourself.