Scrcpy 4.0 makes virtual Android displays feel like desktop apps

Scrcpy (short for “screen copy”) is one of the best ways to control your Android phone from your PC. This free, open-source app lets you mirror your Android phone’s screen on your PC and control it with a keyboard and mouse. It has a whole bunch of neat features, and the cherry on top is that it works on Windows, macOS, and Linux — so you’re not left behind, irrespective of your desktop OS. Scrcpy just hit a milestone v4.0 update that swaps out its underlying framework and introduces some highly requested quality-of-life features that dramatically improve how virtual displays and windowing are handled.

The most significant architectural change in scrcpy 4.0 is the migration from SDL2 (Simple DirectMedia Layer) to SDL3. While backend engine updates don’t always translate to user-facing thrills, this transition brings an immediate visual fix. Thanks to new APIs available in SDL3, scrcpy now natively preserves your device’s aspect ratio when resizing the desktop window.

Previously, freely resizing the window would result in annoying letterboxing and black borders around the Android UI. Now, the window scales perfectly with the display. Purists who actually want the black borders can revert to the old behavior using the “–no-window-aspect-ratio-lock” flag.

Building on the virtual display capabilities introduced in earlier builds, v4.0 adds a powerful new flex display feature. This allows a virtual Android display to be resized dynamically right alongside the client window on your PC. So instead of just mirroring your phone’s physical screen, you can spin up a specific application in a standalone, resizable window that behaves almost like a native desktop app.

Here are the other quality-of-life changes that are available in the latest release:

• Non-Invasive “Keep Active” Mode: Previously, preventing your phone from falling asleep while mirrored meant using the “–stay-awake” flag, which actively altered your device’s global screen-timeout settings. The new “–keep-active” command is much cleaner: it simply sends periodic user-activity signals to the system. This keeps the screen alive without messing with your system-level OS settings.
• Live Camera Controls: If you use your phone as a webcam or stream its camera feed, you can now adjust hardware settings like the flash, optical, and digital zoom levels, etc, on the fly.
• Clearer Disconnections: In older builds, a dropped connection caused the scrcpy window to vanish instantly, leaving users wondering if the software had abruptly crashed. Now, if your ADB connection drops, a clear “disconnected” icon displays on the screen for two seconds before the window gracefully closes.