enricobuehler
3f96e96106
Drop the "Linux-first" framing across the README and docs site in favor of first-class Linux AND Windows hosts, and surface the Windows IDD-push virtual-display path as a distinct differentiator (punktfunk's own indirect display driver the host pushes frames into — a real virtual display, no physical monitor or dummy plug, even on the secure desktop). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
72 lines
3.6 KiB
Markdown
72 lines
3.6 KiB
Markdown
---
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title: How It Works
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description: The ideas behind punktfunk — per-client virtual displays, the two protocols, and trust.
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---
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You don't need to know any of this to use punktfunk, but it helps to understand what's happening
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when you connect.
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## A virtual display, sized to your device
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When a client connects, the host asks your desktop to create a **new virtual display** at exactly the
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client's resolution and refresh rate, captures that display, and streams it. The virtual display is
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real to your desktop — apps can be moved onto it, games open on it — but it isn't tied to any physical
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monitor. When the client disconnects, the virtual display goes away.
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That's why a 1080p60 laptop and a 1440p120 desktop can stream from the same host **at the same time**,
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each at its own mode — they each get their own virtual display.
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How the virtual display is created depends on your host:
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| Host | How |
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|---|---|
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| **GNOME** (Mutter) | A virtual monitor via the screen-cast API |
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| **KDE Plasma** (KWin) | A virtual output via KWin's screencast |
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| **Bazzite / Steam** (gamescope) | A nested gamescope session launched at the client's mode |
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| **Sway** (wlroots) | A headless output added to the running session |
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| **Windows** | A virtual-display driver — including punktfunk's own **indirect display driver** the host pushes frames straight into — a real virtual display, no physical monitor, even on the secure desktop |
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That last one is the distinctive part on Windows: rather than only capturing an existing screen,
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punktfunk has **its own indirect display driver (IDD)**, and the host can push finished frames
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**straight into the driver**. You get the same on-the-fly virtual display the Linux compositors give
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you — at the client's exact mode, with no physical monitor or dummy HDMI dongle, and even on the
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secure desktop (UAC / lock screen). That tight, push-based integration is unusual among Windows
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streaming hosts.
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## From screen to GPU to wire
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Captured frames never touch the CPU on their way to the encoder. They go straight from the
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compositor to the GPU's NVENC hardware encoder (HEVC/H.264/AV1) and out to the network — a **zero-copy
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GPU path** that keeps latency low even at high resolutions and frame rates.
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## Two protocols
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punktfunk speaks two protocols over the same host:
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- **GameStream** — the protocol Moonlight uses. Any [Moonlight](/docs/moonlight) client connects with
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no special software. This is the most compatible way in.
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- **punktfunk/1 (native)** — a purpose-built protocol with a QUIC control channel and a UDP data
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channel hardened with forward error correction and encryption. It's lower-latency and more resilient
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on imperfect networks, and it's what the [native clients](/docs/clients) (Apple, Linux, Windows,
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Android) use.
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Both run from a single host process, so you don't choose up front — Moonlight clients use GameStream,
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the native clients use punktfunk/1.
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## Pairing and trust
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The first time a device connects, you pair it: the host shows a short **PIN**, you type it into the
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client, and the two remember each other. After that the device reconnects automatically on a pinned
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cryptographic identity — no PIN, no account, no cloud. See [Pairing & Trust](/docs/pairing).
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## Finding hosts
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Hosts advertise themselves on your local network, so clients can **discover** them automatically
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instead of needing an IP address. The native clients and Moonlight both list hosts they find on the
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LAN.
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## Multiple devices at once
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A host can stream to several clients simultaneously — your laptop and your TV both viewing (and
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controlling) the desktop, each at its own resolution. See [Multiple devices](/docs/configuration#multiple-devices).
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