Article: Pixel Streaming in Linux containers
Linux support for the Unreal Engine’s Pixel Streaming system is now available to all Engine licensees.
Posted: 12 February 2020
The Pixel Streaming for Linux project has concluded!
Official Linux support has now been merged into the upstream Unreal Engine starting in version 4.27.0 and the Pixel Streaming for Linux project has achieved its mission! Both the 4.23 and 4.25 versions of Pixel Streaming for Linux are now deprecated and will no longer be supported.
We recommend that all developers upgrade to Unreal Engine 4.27.0 or newer to enjoy the many improvements that were made to Pixel Streaming during and after the integration process. Please direct all support queries for the 4.27 implementation and newer to Epic Games through their official communication channels.
The existing text of this article is preserved below for historical reasons and reflects the state of the Pixel Streaming for Linux at the time that it was last updated in February 2021, immediately following the release of the 4.25 version.
Epic Games describes the Unreal Engine’s Pixel Streaming system as the “ideal solution for distributing real-time, interactive content to multiple types of devices”. 1 However, a significant limitation of the official Pixel Streaming reference implementation is that it only supports rendering on Windows host systems and relies on APIs that are not supported by Microsoft’s experimental implementation of GPU acceleration inside Windows Server containers, precluding its use in a container-based environment. The inability to deploy Pixel Streaming applications inside GPU-accelerated containers increases both the complexity and cost of running these applications at scale in the cloud.
In November 2019, myself and my colleague Aidan Possemiers began work on implementing Linux support for the Pixel Streaming system in Unreal Engine 4.23 and released the video shown below to demonstrate our progress. I’m happy to report that our implementation (dubbed “Pixel Streaming for Linux”) is now available for use by all Unreal Engine licensees, and will also be available for use in the upcoming Admiral CI/CD system for developers who wish to utilise automated CI/CD pipelines for their Pixel Streaming applications.
The sections below demonstrate how to get started with Pixel Streaming for Linux in GPU-accelerated Linux containers today.
Where to get the code and file issues
The source code of Pixel Streaming for Linux is available in different locations based on the supported version of the Unreal Engine:
Unreal Engine 4.23: the code for this version can be found in the branch
4.23.1-pixelstreamingof my fork of the UnrealEngine GitHub repository (GitHub login required). This version supports OpenGL only, not Vulkan.
Unreal Engine 4.24: Epic Games made a number of significant architectural changes in the way Pixel Streaming is implemented in 4.24, so our implementation of Linux support for 4.23 could not be simply ported over without major alterations. Although we began early work on a 4.24 port, we ultimately scrapped this version in favour of focussing all of our attention on 4.25 instead, which is the first version of the Unreal Engine to support offscreen rendering with Vulkan under Linux.
Unreal Engine 4.25: the code for this version can be found in the branch
4.25-pixelstreamingof Aidan’s fork of the UnrealEngine GitHub repository (GitHub login required). This version supports Vulkan only, not OpenGL. Note that NVIDIA CUDA is required in order to build and run this version, since CUDA is used to implement the interop between Vulkan and the NVENC video encoder.
Note that Unreal Engine 4.25 is the first Engine version to support offscreen rendering with Vulkan under Linux, and is also the version that deprecated OpenGL, so each version of Pixel Streaming for Linux is limited to only the rendering backend supported by the corresponding Engine version.
A separate public repository has been created to provide the issue tracker for Pixel Streaming for Linux: https://github.com/adamrehn/pixel-streaming-linux. If you encounter any problems, please file your issues against this repository.
Building container images
You can build container images with Pixel Streaming for Linux support using ue4-docker, in the same manner that you would create images for any custom version of the Engine.
To build container images for the Unreal Engine 4.23 version of Pixel Streaming for Linux:
To build container images for the Unreal Engine 4.25 version of Pixel Streaming for Linux:
You can then use a Docker multi-stage build to build and package your Pixel Streaming application inside the created container image, copying the packaged files into a new container image based on the lightweight ue4-runtime base image at the end of the process. (See the relevant section of the Unreal Containers community hub documentation for more details on this process.)
An example Dockerfile might look something like this:
To run the container image produced by this Dockerfile your host system will need an NVIDIA GPU, the latest NVIDIA binary drivers, and the NVIDIA Container Toolkit (formerly known as NVIDIA Docker.) For more information about running Linux containers with GPU acceleration, see the NVIDIA Container Toolkit page of Unreal Containers community hub documentation.
How you run the packaged Pixel Streaming application inside the container will vary depending on the version of the Unreal Engine being used. For Unreal Engine 4.23, you will need to run the packaged project itself, the
WebRTCProxy program (which was subsequently merged into the Pixel Streaming plugin itself in Unreal Engine 4.24) and a signalling server. For Unreal Engine 4.25, you will just need to run the packaged project and the signalling server. For more information, see the official Pixel Streaming documentation.
Epic Games white paper: Streaming Unreal Engine content to multiple platforms ↩