Virtual Network Stream Deck

[lukasMega]

Hello,
I'm trying to create virtual (or "mock") Stream Deck MK.2 device (15 buttons, 5x3) and use it as Network Dock

• it has custom webUI
• so it should be able to connect it to Elgato Stream Deck app. Unfortunately it's not working.

BUT Companion app works flawlessly, confirming the base protocol is correct.

Goal - what I don't know:

• Identify what the Elgato Desktop validates differently from Companion

Pairing in Elgato app is partially working:

I saw in Elgato app new network device appeared 1x (blinks - shows for couple of milliseconds) and immediately disappears.

• I think Elgato app briefly shows the device while initializing then removes it.

Also I saw first button on webUI has changed to full black image - so Elgato app sends request to my app and it rendered first button. I

I noticed after pairing it as "Add Network Device" it added new device under Preferences - Devices 2x:

• one as Network device
• and second as "Stream Deck 2" (beause "Stream Deck" was there already)
• but I see no key images in my webUI

My ideas:

• Firmware byte format — real devices have non-zero bytes at positions 2-5 of the firmware response (e.g., 05 0C B2 CD B1 35 ...). We send all zeros there. The Elgato app might validate those bytes.
• The Elgato app may be waiting for something specific that I'm simply not sending (maybe a specific CORA event type or a different initial handshake order)

Could you please help me and point me where I should take a look?
Thank you

[Julusian]

I don't know how much I will be able to help here, its going to be a lot of guesswork. My approach to reverse engineering something like this is to start by using a wireshark capture of the real thing and effectively re-play the packets. Once that works I move on to try to generate packets correctly. Usually I do this when there is no prior code to base it on though, but maybe this would be a good approach for certain packets which you are unsure of. And the TCP nature will complicate it, because of the cora headers which will need generating correctly

Firmware byte format

Possibly, but I don't think this will matter. those bytes are for a checksum of the firmware, I cant see why it would care what they are.

The Elgato app may be waiting for something specific that I'm simply not sending

Yeah probably this. But figuring out what is the challenge. One thing to figure out is whether it is the network dock connection that is being closed or the secondary device.

I have a feeling there were a few commands that this library doesnt implement as it has no need for them (same with some values inside of messages), but I couldnt say what they were.. Hopefully they can be at least discovered by what report ids it sends and we dont have an answer for

[lukasMega]

Yes, I’m aware of the jimp library (it’s slow); I plan to replace it with something faster. Thanks for the suggestion.

I also plan to reduce my app's size. Node.js is large (Deno and Bun are large too - they're over ~50 MB). I know the smallest option would be to rewrite the app in Rust, Go, or Zig, but I don’t want to do that and I’m not familiar with those languages.

I prefer to stay with TypeScript, so I plan to port the app to txiki.js (a small runtime on top of QuickJS-NG, only ~6 MB). I've already done some work with txiki.js and I like it (it's also multi-platform)

// update: see how it is slow currently with jimp:

click to see 2MB GIF

// update @2: with @julusian/image-rs it is noticeably faster:

click to see 0.5 MB GIF

[Julusian]

And now I have one on the way (the waveshare board) 😆

It appears the waveshare board is using an early version of the P4 chip (ESP32-P4NRW32) that has a semi-broken usb implementation, meaning it isnt capable of the full usb rate that a streamdeck needs.

I'm getting HCD DWC: EP MPS (1024) exceeds supported limit (512) when trying to open the streamdeck, which gemini and github are suggesting is due to the semi-broken chip.

Thats a shame. I cant find anyone selling a board with the fixed revision (ESP32-P4NRW32X) yet. Maybe something to check back on in a few months

[lukasMega]

oh, that was probably the issue and reason why it wasn't working for me couple of weeks ago. I'm aware that ESP32-P4 has some new revision (but everyone currently selling 1.x revisions). I hoped the new revision solves only some hardware-related issues... I already bought 2x ESP32-P4 :/ (I have also one from Waveshare and second one is cheaper from Guition)
So we need to wait for new revision to become available.

Meanwhile I was able to do some progress on my Virtual Stream Deck app (99% in Typescript) and compiled to binary executable with size 4,1 MB for macOS (+ another 3MB binary in Go for simple tray icon & menu).
As I wrote previously I have used txiki.js - but slimmed down version (compiled from sources with one patch to remove sqlite and WASM). Only tested on macOS so far.

[lukasMega]

my proof of concept:

click to see GIF

tested only on macOS with Mirabox 293V3 and Stream Deck Mini

[lukasMega]

hi @Julusian, if you are still interested, here is my initial public version:

Page/docs: https://lukasmega.github.io/DeckBridge/

• (repo: https://github.com/lukasMega/DeckBridge)