The Missing Piece: Building VkCapture Natively for Flawless Flatpak OBS Game Capture on Fedora 42

1. Introduction: The Power of VkCapture & The Flatpak Convenience

Hello Fedora enthusiasts and Linux gamers! If you're like me, you love the power and flexibility of Linux for gaming and content creation. OBS Studio is an incredible tool for streaming and recording, and running it as a Flatpak on Fedora offers a super convenient way to keep it updated and manage it's dependencies.

But what if i told you there's a way to get even better performance when capturing your vulkan-based games?

Enter vkcapture. This isn't your standard window or screen grab. vkcapture is a specialized method for hooking directly into Vulkan games.

Why should you care about vkcapture?

Performance Boost: We're talking potentially significant reductions in overhead compared to other capture methods. This means smoother gameplay for you, and smoother video for you audience.

Direct Capture: It taps right into the game's rendering pipeline. Many users might miss out on this because it's not always the default or most obvious option. That's why i consider it an “underrated gem”, especially for us Linux users.

2. The Scenario: Flatpak OBS Meets Native Linux Games

So, here's the setup we're tackling:

You've got OBS Studio installed as a Flatpak from Flathub (directly or via your package manager) on your awesome Fedora system.

You're playing Vulkan-based games that are installed natively on Fedora (i.e., native Steam client, Lutris, Heroic Game Launcher etc.). This is a common and great setup! But when you try to use vkcapture in this scenario, you might hit a snag.

3. The “Catch”: Why Vkcapture Might Not Just Work Out-Of-The-Box

You open your Flatpak OBS, see the “Game Capture” source option, and get excited. But when you try to capture your native Vulkan game.. nothing. Or, it simply doesn't work as expected. What gives?

Here's the crucial bit:

For vkcapture to do its magic, your Vulkan game needs to load a special component called a Vulkan layer. Think of it as a small piece of software that sits between your game and your graphics driver, allowing vkcapture to access the game's rendered frames.

The Problem:

Your natively installed game lives outside the OBS Flatpak's isolated world (its “sandbox”). It typically can't “see” or use any Vulkan layers that might be bundled inside the Flatpak. So, even if Flatpak OBS has the vkcapture plugin ready to receive data, your native game doesn't know how to send it because it can't load the necessary layer.

This is the “missing piece” we're going to put in the place!

4. The Solution: Building the Vkcapture Vulkan Layer Natively on Fedora

To bridge this gap, we need to build and install the vkcapture Vulkan layer directly onto our Fedora system, making it accessible to our native games. Don't worry, it sounds more intimidating that it is! Let's break it down.

A. Getting the source code for obs-vkcapture

First, we need the source code for the obs-vkcapture layer.

git clone https://github.com/nowrep/obs-vkcapture.git
cd obs-vkcapture

B. Installing Build Dependencies on Fedora

Next, we'll gear up our Fedora system with the tools and libraries needed to compile the layer.

Open your terminal and run:

sudo dnf install gcc gcc-c++ make \
    obs-studio-devel \
    vulkan-headers \
    vulkan-loader-devel \
    mesa-libGL-devel \
    mesa-libEGL-devel \
    libX11-devel \
    libxcb-devel \
    wayland-devel \
    wayland-protocols-devel

C. Building the plugin

Inside the obs-vkcapture folder, create a build directory and enter it:

mkdir build
cd build

Compile the plugin

cmake .. -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/usr
make

D. Installing the Layer Natively

Once compiled, we need to install the Vulkan layer files to the correct system directories so your games and the Vulkan loader can find them. This usually involves two main files: the shared object (.so) library and a JSON manifest file.

The good news is that this whole procedure will automatically be completed by executing the following command:

#Inside the build directory
sudo make install

E. Reboot Your Machine

5. Configuring and Using Vkcapture with Flatpak OBS

Alright, the native vkcapture layer is built and installed! Now, let's get it working with your Flatpak OBS.

This is where you tell your native Vulkan game to use the layer we just installed.

The most common way is by setting an environment variable when launching the game.

1. Steam

How to access Launch Options:

  1. In your Steam Library, right-click on the game you want to capture.
  2. Select “Properties...”.
  3. In the “General” tab, you'll find a text box labeled “LAUNCH OPTIONS”.

What to enter:

obs-gamecapture %command%

Note: the %command% part is crucial for Steam; it tells Steam to substitute in the actual game executable and its arguments at that point.

2. Lutris

How to access settings:

a. In Lutris, right-click on the game. b. Select “Configure”. c. Go to the “System options” tab.

In the “System options” tab, find the field labeled “Command prefix”. Enter the following into this field:

obs-gamecapture

d. Click “Save”

3. Heroic Games Launcher

How to access settings:

a. Open Heroic Games Launcher and select the game you want to configure. b. Click on the “Settings” icon for that specific game. c. You'll see sections as shown in your image: “Wrapper command” and “Environment Variables”. d. Locate the “Wrapper command” section. 3. In the field labeled “Wrapper”, enter:

obs-gamecapture

The field next to it labeled “Arguments” (or “Wrapper Arguments”) should generally be left blank when using obs-gamecapture this way. The obs-gamecapture script is designed to precede the main game command that Heroic will launch. 4. Save the settings if there's a save button, or Heroic might auto-save.

5. Adding the Source in OBS Studio

With your game running (and the layer loaded), it's time to add it in OBS:

6. Conclusion

And there you have it! By building the vkcapture Vulkan layer natively on your Fedora system, you've bridged the gap to your Flatpak OBS installation, unlocking potentially much smoother and more performant captures of your native Vulkan games.

It might seem like a few extra steps, but the payoff in quality and performance can be well worth it for serious streamers and content creators. Plus, you've learned a bit more about how Vulkan layers and Flatpak sandboxing interact!

Happy gaming and capturing! Let me know in the comments how this worked for you or if you have any other tips!

⟩ OmniGlitch

⌘ #tech #gaming #opinions