unreal-rtsp-display

Example code for receiving video streams over RTSP using Unreal Engine FSockets and displaying them in real time.

unreal-rtsp-ui-compressed.mp4

When running this example, you will need to configure the address, port, and path of your RTSP server on the actor:

Note: this example currently only supports MJPEG streams over RTSP, which are parsed with the RtpJpegPacket class into JpegFrames. This example uses Unreal Engine's built-in image decoding to decode the jpeg frames into uncompressed image data for use in a UTexture2D.

This example contains a few components:

The RtspClientComponent class: This component can be added to an actor and exposes some functions for connecting to an RTSP server and configuring / controlling the stream. Inside its TickComponent function, it waits for new images (decompressed) to be available and if so, creates a new transient UTexture2D and writes the decompressed data to the new texture. It then broadcasts this new texture using the multicast delegate to any registered listeners.
The RtpPacket, RtpJpegPacket, JpegHeader, and JpegFrame classes which handle the parsing of the media data (as RTP over UDP from the server to the client) and reassembling of multiple networks packets into a single jpeg frame.
The MyRunnable class: used by the RtspClientComponent when it connects to a server it spawns two runnables (Unreal Engine threads) for receiving data from the server on the RTP/UDP socket and the RTCP/UDP socket. The RTP runnable runs a bound function from the RtspClientComponent class which receives the raw data, parses it into jpeg frames, decompresses the jpeg frames, and then updates some mutex-protected data to inform the game thread (RtspClientComponent::TickComponent) that new data is available. This class is also used to allow the FSocket::Connect (TCP connection from RTSP Client to RTSP Server) to run without blocking the main / game thread.
M_Display and M_Display_Inst: these assets in the Content/Materials directory are simple materials which render a texture parameter with optional configuration for the UV mapping of the texture. This material instance is the base for the dynamic material instance that is created at runtime in the RtspDisplay blueprint.
RtspDisplay: This blueprint actor contains an RtspClientComponent and a Plane static mesh component. On BeginPlay it creates a dynamic material instance of the M_Display_Inst which it stores a reference to so that it can dynamically update the texture parameter that the material is rendering. It sets this material on the plane static mesh component. It binds an event to the OnFrameReceived event from the RtspClientComponent and when it receives a message from that event, it sets the new texture to be the dynamic material instance's texture parameter.
W_RtspDisplay: This user widget contains the UI (2D) for interacting with a RtspClientComponent. It is configured by the RtspDisplayMap's level blueprint to be added as the UI to the viewport for the first player controller and to control the RtspClientComponent of the RtspDisplay actor in the level. It provides the UI (display image, URL textbox, and buttons for connect, disconnect, play, and pause) for the RtspClientComponent.

Image of the running example in the editor:

Disconnected (With text box to write URI and connect button): Connected: Playing:

Details

RtspDisplay Actor Blueprint

M_Display Material

RtspDisplay User Widget

Note the image has been set with angle 180 and X scale of -1 so that it matches the camera image that I'm currently sending. May need to be changed for other streams depending on camera orientation.

Its blueprint:

Level Blueprint

Setup for Android App

Follow the setup instructions here.

Note: you will likely have to modify the /Users/Shared/Epic\ Games/UE_5.2/Engine/Extras/Android/SetupAndroid.command file - possibly to point to the right JAVA_HOME directory. In my case I had to modify the JAVA_HOME export in the SetupAndroid.command file to point to /Library/Java/JavaVirtualMachines/adoptopenjdk-8.jdk/Contents/Home and had to install jdk8 specifically.

You will need to set the environment variables (under Android SDK) appropriately, e.g.:

Android SDK : /Users/bob/Library/Android/sdk
Android NDK : /Users/bob/Library/Android/sdk/ndk/25.1.8937393
Location of JAVA : /Library/Java/JavaVirtualMachines/adoptopenjdk-8.jdk/Contents/Home
SDK API Level : android-32
NDK API Level : android-32

For that version of java (jdk 8) which is required to successfully build for android, you can (on macos) install it via:

brew install --cask adoptopenjdk8

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