Trying to understand how QZ talks to Zwift

[EricLauber]

I would like to better understand how QZ takes devices that may not be Zwift compatible and integrate them into Zwift. I'm specifically interested in the QZ->Zwift part of that communication, not the device->QZ part.

I have a project of my own I am building in C# and I would like to emulate the controlling capabilities of the Zwift Play Controllers or Wahoo Kickr Bike. I'm not super familiar with building Bluetooth connectivity but I do have LAN experience. This GP LLama video at 4:11 shows the Wahoo KICKR Bike Shift connecting as a Controller to Zwift over Wi-Fi, so I know Zwift is capable of this.

It seems like QZ has figured some of this out already. In this video QZ shows a "Wahoo KICKR 0000 33" virtual device as a Wi-Fi or LAN-connected device. A similar thing happens in this video as well.

I have been going through the QZ source code trying to understand how this works and it's honestly quite overwhelming.

I'm hoping that if I can get some help to better understand the way QZ is able to present emulated devices to Zwift and to send data to Zwift, I could do something similar for my alternative use case.

I'm seeking to understand:

• The protocols or workflow to present a device over the network to Zwift
• What kinds of Control inputs Zwift accepts. I assume it's all of these functions but maybe there are more?
• How to send these inputs from the emulated device to Zwift.

References to specific source files is helpful, but a walkthrough if the flow of operations, what data has to be sent at which step, and in what format, would be amazing.

[cagnulein]

Why don't you start from here if it's easier for you https://github.com/ajchellew/zwiftplay ?

[EricLauber]

I think that takes me a bit down a different direction. I want to start with the network communication first before understanding the encryption/decryption.

I'm trying to find where or how the "Wahoo Kickr virtual device" shown here gets created.

 
I'm searching through the repo and I see netserial.h which emulates a serial port. I've seen a few things about webservers. There's authentication with Zwift.

In dirconmanager.cpp there is this line, that sounds like it may line up with the screenshot.

OP(WAHOO_KICKR, "Wahoo KICKR $uuid_hex$", DM_MACHINE_TYPE_TREADMILL | DM_MACHINE_TYPE_BIKE, P1, P2, P3)            \

But dirconmanager.cpp seems to be Bluetooth focused, while the screenshot shows a network-connected device. So I'm either missing where this gets setup or I don't understand Qt libraries in C++ well enough.

[cagnulein]

Nope, dirconmanager is the right starting point. It's the main engine of dircon :) I suggest to use claude.ai to give you a great flow chart about this! Roberto Viola Software engineer and open source enthusiast http://robertoviola.cloud Il giorno mer 1 gen 2025 alle 05:03 Eric Lauber ***@***.***> ha scritto:

…

I think that takes me a bit down a different direction. I want to start with the network communication first before understanding the encryption/decryption. I'm trying to find where or how the "Wahoo Kickr virtual device" shown here gets created. image.png (view on web) <https://github.com/user-attachments/assets/90617c26-e98e-4d81-997c-ce09b680bdd2> I'm searching through the repo and I see netserial.h which emulates a serial port. I've seen a few things about webservers. There's authentication with Zwift. In dirconmanager.cpp there is this line, that sounds like it may line up with the screenshot. OP(WAHOO_KICKR, "Wahoo KICKR $uuid_hex$", DM_MACHINE_TYPE_TREADMILL | DM_MACHINE_TYPE_BIKE, P1, P2, P3) \ But dirconmanager.cpp seems to be Bluetooth focused, while the screenshot shows a network-connected device. So I'm either missing where this gets setup or I don't understand Qt libraries in C++ well enough. — Reply to this email directly, view it on GitHub <#2967 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAALYWEOM5T4CT4W6KXA4ET2INSILAVCNFSM6AAAAABUM4VUBCVHI2DSMVQWIX3LMV43URDJONRXK43TNFXW4Q3PNVWWK3TUHMYTCNZQHA3TQMI> . You are receiving this because you commented.Message ID: ***@***.*** com>

[EricLauber]

@cagnulein what development environment are you using to build/develop and debug? According to your CI workflow it looks like Python and Qt on Windows, do you use VS Code or some other environment?

I want to step through with the debugger and see what steps are happening in order. It's starting to make sense to me...

[cagnulein]

Qt creator Roberto Viola Software engineer and open source enthusiast http://robertoviola.cloud Il giorno dom 5 gen 2025 alle 18:53 Eric Lauber ***@***.***> ha scritto:

…

@cagnulein <https://github.com/cagnulein> what development environment are you using to build/develop and debug? According to your CI workflow it looks like Python and Qt on Windows, do you use VS Code or some other environment? I want to step through with the debugger and see what steps are happening in order. It's starting to make sense to me... — Reply to this email directly, view it on GitHub <#2967 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAALYWHNPCW55BHKIBMMUB32JFWSHAVCNFSM6AAAAABUM4VUBCVHI2DSMVQWIX3LMV43URDJONRXK43TNFXW4Q3PNVWWK3TUHMYTCNZUGA4DKNQ> . You are receiving this because you were mentioned.Message ID: ***@***.*** com>

[EricLauber]

My lack of experience in Qt is leading to road blocks, unfortunately I'm not even able to get a build to complete.

[cagnulein]

Follow the installation guide, you need to install that module too
it's a submodule of qz

[EricLauber]

Looks like the installation instructions don't have a specific guide for Windows. I'll follow the CI workflow and see if I can make that work. I'm hoping to run the victory-dircon or Zwift-Play-(within-Zwift-Ride)-Two-buttons-for-shifting-gears branches to step through the progress you've made.

[cagnulein]

You just need to run the e e in the zip

I didn't test that branch on windows