Device

Four capture sources share two traits — VideoCapture (screen, window, camera) and AudioCapture (microphone) — both a poll loop over frames, no encoding involved. What differs per source is how much of it is wired into mediaway::platform’s cross-platform dispatch versus needing a platform-specific type directly.

Screen — fully dispatched

let config = VideoCaptureConfig::screen(Select::Default, Rational::new(1, 30));
let mut capture = platform::ScreenCapture::open(&config)?;

while let Some(frame) = capture.poll_frame()? {
    // consume frame …
    capture.release_frame()?;
}
capture.close()?;

release_frame matters for GPU-backed sources: it frees the backend’s hold on that frame (e.g. DXGI’s ReleaseFrame) before the next poll_frame can acquire again.

Try it: cargo run --example capture_screen — examples/device/capture_screen.rs.

Microphone — fully dispatched

let config = AudioCaptureConfig::microphone(Rational::new(1, 48_000));
let mut mic = platform::Microphone::open(&config)?;

while let Some(frame) = mic.poll_frame()? {
    // frame.data is interleaved PCM
}

Try it: cargo run --example capture_microphone — examples/device/capture_microphone.rs.

Camera — platform type directly

Camera capture isn’t wired into platform yet, so reach for the Windows backend directly — it compiles on every platform (a stub returns CaptureError::Unsupported off Windows, same failure shape as a missing camera on Windows itself):

let config = VideoCaptureConfig {
    source: CaptureSource::Camera { select: Select::Default },
    time_base: Rational::new(1, 30),
    // Media Foundation's camera backend is CPU-frames-only today.
    output: CaptureOutputPreference::CpuFramesOk,
    gpu_device: None,
};
let mut camera = mediaway_device::windows_camera::WindowsCameraCapture::open(&config)?;

Try it: cargo run --example capture_camera — examples/device/capture_camera.rs.

Window — needs a caller-owned GPU device

Window capture (WinRT Graphics Capture) is the one Windows source with no CPU-only path — open() requires both a live HWND and a caller-owned ID3D11Device handed in as gpu_device: Some(GpuDeviceHandle::DirectX11(handle)). Obtaining either means calling raw Win32/WinRT FFI, which is unsafe — out of scope for a plain example, so examples/device/capture_window.rs only shows the config shape. Off Windows, platform::WindowCapture::open returns the concrete per-target capture type (WGC, portal, ScreenCaptureKit). The config also takes cursor (CursorCapture::Excluded by default) and an optional region — WGC only, and a region away from the window’s origin costs one GPU copy per frame. For a complete, hardware-tested version with the unsafe fully contained and documented, see crates/mediaway-device/src/windows_desktop/lib_tests.rs’s open_window_capture_foreground_or_skip test in the repository.

What’s available where

See Device for the full platform/source support matrix.