libdrmtap

Safe Rust wrapper for libdrmtap — DRM/KMS screen capture for Linux.

Capture the screen at the kernel level: login screens, Wayland, headless — no user prompts.

Frames come back as 8-bit BGRA. Tiled/compressed framebuffers are GPU-detiled, and HDR10 scanouts (PQ/BT.2020) are tone-mapped to SDR when the connector reports HDR (P010 overlay-video and HLG excepted).

⚠️ Testing Status

Verified on virtio_gpu (QEMU/Parallels VMs), Intel Meteor Lake (i915, dual 4K, EGL CCS detiling), and NVIDIA Jetson Orin Nano (nvidia-drm, Wayland).

The AMD (amdgpu) backend is validated on real hardware (RX Vega 64, gfx9, via EGL detile). Hit a problem on other AMD hardware? Please report results.

Installation

[dependencies]
libdrmtap = "0.3"

This pulls in libdrmtap-sys 0.4.7, which embeds and statically compiles the C sources (and the privilege helper) — no system libdrmtap install needed.

Example

use libdrmtap::DrmTap;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut tap = DrmTap::open(None)?;

    println!("GPU: {}", tap.gpu_driver().unwrap_or("unknown".into()));

    // List displays
    for d in tap.list_displays()? {
        println!("{}: {}x{}@{}Hz", d.name, d.width, d.height, d.refresh_hz);
    }

    // Capture a frame with mapped pixel data
    let frame = tap.grab_mapped()?;
    println!("Captured: {}x{} stride={}", frame.width(), frame.height(), frame.stride());

    if let Some(pixels) = frame.data() {
        println!("First pixel (BGR): {:02x}{:02x}{:02x}",
                 pixels[0], pixels[1], pixels[2]);
    }

    Ok(())
}

Features

• DrmTap::open() — auto-detect GPU and display
• grab() — zero-copy DMA-BUF fd (for hardware encoders)
• grab_mapped() — mmap'd pixel data (for software access)
• get_cursor() — cursor position + ARGB image
• list_displays() — enumerate connected monitors
• displays_changed() — hotplug detection

Requirements

• Linux with DRM/KMS (kernel 4.20+ for the tiled/modifier path; linear/VM framebuffers work on older kernels)
• A C compiler — libdrmtap-sys compiles its embedded C sources statically, so there is no system libdrmtap install required
• For unprivileged capture: drmtap-helper with cap_sys_admin+ep (the helper binary is built by libdrmtap-sys)

License

MIT