# Mirror Hall Virtual Network Displays for Linux Devices > [! note]- > The content of this page is generated by audio/video transcription and text transformation from the content and links of this source. Source: [https://fosdem.org/2025/schedule/event/fosdem-2025-4527-mirror-hall-building-virtual-network-displays-to-bridge-mobile-and-desktop/](https://fosdem.org/2025/schedule/event/fosdem-2025-4527-mirror-hall-building-virtual-network-displays-to-bridge-mobile-and-desktop/) <video src="https://video.fosdem.org/2025/h2214/fosdem-2025-4527-mirror-hall-building-virtual-network-displays-to-bridge-mobile-and-desktop.av1.webm" controls></video> ## Summary & Highlights: The session 'Mirror Hall: Building virtual network displays to bridge mobile and desktop' at FOSDEM 2025 introduces Mirror Hall, an open-source application aimed at creating virtual network displays for Linux devices. It leverages technologies like GStreamer, PipeWire, and D-Bus to enable seamless screen sharing and extended desktop functionalities across mobile and desktop platforms. The session highlights the challenges of existing proprietary solutions and presents Mirror Hall as a flexible, community-driven alternative. **Introduction to Virtual Network Displays** The session begins by addressing the fragmented landscape of wireless displays and the need for standardized, open-source solutions. It introduces the concept of virtual network displays, allowing Linux devices to serve as extended monitors, and outlines the technical approach using optimized video pipelines and low-latency UDP streaming. **Technical Insights and Demonstration** The presentation delves into the technical aspects of Mirror Hall, showcasing the use of GStreamer and PipeWire for efficient video streaming. It explains the creation of virtual monitors using the GNOME 40 backend and the integration of hardware acceleration for improved performance. A demonstration of the Mirror Hall app illustrates its capabilities and potential applications. **Challenges and Future Directions** The session discusses the limitations of current solutions, such as high latency and proprietary protocols, and the challenges in achieving bidirectional streaming. Future development plans include improving encryption, expanding compatibility, and enhancing user interface components. The speaker invites collaboration from the community to further refine and expand the project's reach. ## Importance for an eco-social transformation Mirror Hall holds significant potential for eco-social transformation by promoting open-source, community-driven solutions that enhance the interoperability of devices. Its application in eco-social design can lead to more sustainable and cost-effective ways to repurpose older devices, reducing electronic waste. The project encourages collaboration and knowledge sharing, aligning with social and ethical values of inclusivity and transparency. Challenges include overcoming technical barriers related to network protocols and ensuring broader adoption across different platforms and hardware. Eco-social designers can leverage tools like GStreamer and PipeWire to create innovative solutions that address both environmental sustainability and social equity. ## Slides: | | | | --- | --- | | ![[FOSDEM 2025/assets/Mirror-Hall-Building-virtual-network-displays-to-b/preview_001.jpg\|300]] | Mirror Hall aims to create virtual network displays that bridge the gap between mobile and desktop devices. This innovative solution allows Linux devices to function as extended monitors, fostering greater integration and flexibility in device usage. | ![[FOSDEM 2025/assets/Mirror-Hall-Building-virtual-network-displays-to-b/preview_002.jpg\|300]] | In 1993, Xerox PARC pioneered the concept of 'ubiquitous computing', envisioning a future where devices seamlessly interact. Mirror Hall builds on this vision by enabling peer-to-peer network displays, enhancing the interoperability of Linux devices. | ![[FOSDEM 2025/assets/Mirror-Hall-Building-virtual-network-displays-to-b/preview_003.jpg\|300]] | Despite the prevalence of devices, seamless interface remains challenging due to proprietary protocols. Mirror Hall addresses this by offering an open solution for virtual desktop mirroring, allowing Linux devices to extend screens across platforms. | ![[FOSDEM 2025/assets/Mirror-Hall-Building-virtual-network-displays-to-b/preview_004.jpg\|300]] | Simple mirroring involves replicating a primary screen on another device using screen recording APIs. While Linux offers several solutions, Mirror Hall enhances this by enabling virtual display creation, expanding functionality beyond simple mirroring. | ![[FOSDEM 2025/assets/Mirror-Hall-Building-virtual-network-displays-to-b/preview_005.jpg\|300]] | Virtual mirroring is achievable by creating a virtual display if the system's graphical stack supports it. Mirror Hall leverages this capability to offer virtual network displays, enhancing device interoperability. | ![[FOSDEM 2025/assets/Mirror-Hall-Building-virtual-network-displays-to-b/preview_006.jpg\|300]] | Apple's Sidecar allows certain iPads to serve as extended screens for macOS. Mirror Hall aims to provide a similar capability for Linux devices, offering an open-source alternative to proprietary solutions. | ![[FOSDEM 2025/assets/Mirror-Hall-Building-virtual-network-displays-to-b/preview_007.jpg\|300]] | Existing wireless display solutions often rely on proprietary protocols and suffer from high latency. Mirror Hall seeks to overcome these limitations by using open protocols and optimizing for speed, enabling bidirectional streaming. | ![[FOSDEM 2025/assets/Mirror-Hall-Building-virtual-network-displays-to-b/preview_008.jpg\|300]] | Virtual mirroring across multiple devices is possible with the right conditions, such as available video buffers and hardware encoding support. Mirror Hall explores these possibilities to enhance device interoperability. | ![[FOSDEM 2025/assets/Mirror-Hall-Building-virtual-network-displays-to-b/preview_009.jpg\|300]] | Bidirectional virtual mirrors allow devices to choose their role as a streamer or receiver dynamically. Mirror Hall aims to implement this flexibility, facilitating seamless interaction between Linux devices. | ![[FOSDEM 2025/assets/Mirror-Hall-Building-virtual-network-displays-to-b/preview_010.jpg\|300]] | Since 2020, Mirror Hall has evolved from a prototype using GNOME's virtual monitor API to a full-fledged application. It has undergone several iterations, with the first release occurring in September 2024. | ![[FOSDEM 2025/assets/Mirror-Hall-Building-virtual-network-displays-to-b/preview_011.jpg\|300]] | Mirror Hall enables bidirectional mirroring, allowing devices to act as both streamers and receivers. This capability enhances the versatility of Linux devices in a networked environment. | ![[FOSDEM 2025/assets/Mirror-Hall-Building-virtual-network-displays-to-b/preview_012.jpg\|300]] | Mirror Hall comprises several components: libmirror for creating virtual displays, libcast for streaming video, and libnetwork for network communication. These elements work together to facilitate seamless device integration. | ![[FOSDEM 2025/assets/Mirror-Hall-Building-virtual-network-displays-to-b/preview_013.jpg\|300]] | Mirror Hall's architecture involves D-Bus for virtual display creation, UDP or RTSP for streaming, and mDNS for network communication. This setup ensures efficient and flexible device interaction. | ![[FOSDEM 2025/assets/Mirror-Hall-Building-virtual-network-displays-to-b/preview_014.jpg\|300]] | Retrocompatible mirroring allows Mirror Hall to function on devices without the app installed, using RTSP and CLI tools. This feature enhances the application's accessibility and usability across platforms. | ![[FOSDEM 2025/assets/Mirror-Hall-Building-virtual-network-displays-to-b/preview_015.jpg\|300]] | The build process for Mirror Hall involves compiling its various components, ensuring compatibility with different hardware and software environments. This step is crucial for achieving optimal performance. | ![[FOSDEM 2025/assets/Mirror-Hall-Building-virtual-network-displays-to-b/preview_016.jpg\|300]] | Creating virtual sinks in Mirror Hall involves using D-Bus calls to GNOME's screencast APIs. This process enables the creation of virtual displays without direct interaction with the Wayland or kernel. | ![[FOSDEM 2025/assets/Mirror-Hall-Building-virtual-network-displays-to-b/preview_017.jpg\|300]] | Mirror Hall utilizes GNOME's screencast APIs to create virtual displays. This involves a series of D-Bus calls to establish and manage streaming sessions, leveraging PipeWire for efficient video handling. | ![[FOSDEM 2025/assets/Mirror-Hall-Building-virtual-network-displays-to-b/preview_018.jpg\|300]] | | | ![[FOSDEM 2025/assets/Mirror-Hall-Building-virtual-network-displays-to-b/preview_019.jpg\|300]] | Once a PipeWire stream is obtained, it can be transmitted over the network using GStreamer. This involves encoding the stream, segmenting it into packets, and transmitting it via UDP or RTSP. | ![[FOSDEM 2025/assets/Mirror-Hall-Building-virtual-network-displays-to-b/preview_020.jpg\|300]] | Receiving streams in Mirror Hall involves setting up a UDP listener and decoding incoming video packets. This process allows devices to function as receivers, completing the bidirectional streaming capability. | ![[FOSDEM 2025/assets/Mirror-Hall-Building-virtual-network-displays-to-b/preview_021.jpg\|300]] | Mirror Hall's pipeline generator optimizes video streaming for minimal latency, prioritizing speed over precision. This approach ensures efficient streaming even in challenging network conditions. | ![[FOSDEM 2025/assets/Mirror-Hall-Building-virtual-network-displays-to-b/preview_022.jpg\|300]] | Mirror Hall requires specific UDP ports for network communication. Users must configure their firewalls accordingly, using tools like iptables or firewalld, to ensure seamless operation. | ![[FOSDEM 2025/assets/Mirror-Hall-Building-virtual-network-displays-to-b/preview_023.jpg\|300]] | Recent GNOME versions have introduced compatibility issues with Mirror Hall. Users are advised to exercise caution and test thoroughly, especially on ARM devices, to ensure stability. | ![[FOSDEM 2025/assets/Mirror-Hall-Building-virtual-network-displays-to-b/preview_024.jpg\|300]] | Future developments for Mirror Hall include improving encryption, enhancing stability, and integrating input method mirroring. These enhancements aim to expand the application's capabilities and security. | ![[FOSDEM 2025/assets/Mirror-Hall-Building-virtual-network-displays-to-b/preview_025.jpg\|300]] | As Mirror Hall progresses, the focus is on refining components, improving transmission stability, and expanding compatibility. Collaboration with the community is encouraged to drive further development. | ![[FOSDEM 2025/assets/Mirror-Hall-Building-virtual-network-displays-to-b/preview_026.jpg\|300]] | The presentation acknowledges contributions from various individuals and provides references for further reading. It is released under a Creative Commons license, promoting open access and collaboration. | ![[FOSDEM 2025/assets/Mirror-Hall-Building-virtual-network-displays-to-b/preview_027.jpg\|300]] | Additional resources and contact information for Mirror Hall are provided, encouraging community engagement and collaboration. The session concludes with a call for questions and feedback. ## Links [Mirror Hall Overview](https://notes.nokun.eu/post/2024-09-22-mirrorhall/) [GitLab Repository](https://gitlab.com/nokun/mirrorhall)