Struct GstreamerVideoCapture 

pub struct GstreamerVideoCapture {
    child: Child,
    stdout: ChildStdout,
    width: u32,
    height: u32,
    framerate: f64,
    next_index: u64,
    raw_buffer: Vec<u8>,
}

Streaming video capture wrapping a gst-launch-1.0 child process.

Fields

child: Child

stdout: ChildStdout

width: u32

height: u32

framerate: f64

next_index: u64

raw_buffer: Vec<u8>

Pre-allocated scratch buffer for the raw bytes of one frame.

Implementations

impl GstreamerVideoCapture

pub fn from_default_camera( width: u32, height: u32, framerate: u32, ) -> Result<Self, Error>

Build a capture from the default OS camera via gst’s autovideosrc (M-CAM.0 / AUT-254).

On macOS autovideosrc routes to avfvideosrc; on Linux v4l2src; on Windows mfvideosrc. Caller picks the output dimensions + framerate — gst’s videoconvert step resizes / converts whatever the camera natively produces.

**macOS gotcha:** `avfvideosrc` requires
`NSCameraUsageDescription` in the bundled app's Info.plist.
Without it the gst pipeline fails with a misleading "device
busy" error AND the OS permission prompt never shows. See
`crates/app/tauri.conf.json` for the project's declaration.

Errors

• Error::InvalidFormat if any dimension is zero.
• Error::Spawn if gst-launch-1.0 isn’t on PATH.
• Error::NoStdout if the child’s stdout pipe is missing (shouldn’t happen — we request it explicitly).

Cross-OS behaviour: on a host without a default camera the pipeline spawns but next_frame returns Error::EndOfStream as soon as the OS denies access / reports no device. Integration tests should call default_camera_available first and skip cleanly.

pub fn from_camera( camera_id: &str, width: u32, height: u32, framerate: u32, ) -> Result<Self, Error>

Build a capture pinned to a specific camera resolved by its stable id (M-CAM.4). Re-probes list_cameras() at call time to turn camera_id into the OS-native source element + props (avfvideosrc device-index=N on macOS, mfvideosrc device-path=... on Windows, v4l2src device=... on Linux).

If the camera is in the enumeration but the parser couldn’t extract a gst_source for it (unusual — would indicate a gst-device-monitor output format the parser didn’t recognise), falls back to autovideosrc with a tracing::warn so the user still sees some camera. The picker just won’t be honored.

Errors

• Error::InvalidFormat if any dimension is zero.
• Error::CameraNotFound if no enumerated camera matches camera_id (typical: the camera was unplugged between list_cameras() and from_camera()).
• Error::Spawn if gst-launch-1.0 isn’t on PATH.
• Error::NoStdout if the child’s stdout pipe is missing.

pub fn test_source( width: u32, height: u32, framerate: u32, ) -> Result<Self, Error>

Build a capture from videotestsrc at the given dimensions + framerate. The default videotestsrc pattern is the SMPTE colorbars — useful for visual smoke checks because every frame is visually distinct (animated subpattern).

pub fn dimensions(&self) -> (u32, u32)

Width × height the captured frames will carry.

pub fn framerate(&self) -> f64

Framerate the pipeline emits.

pub fn frames_emitted(&self) -> u64

Cumulative frames emitted across next_frame calls.

pub fn next_frame(&mut self) -> Result<VideoFrame, Error>

Read one BGRA frame. PTS is computed from the frame index and the captured framerate.

Errors

• Error::Io on read failures.
• Error::EndOfStream if the pipeline ends mid-frame.

Trait Implementations

impl Debug for GstreamerVideoCapture

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Drop for GstreamerVideoCapture

fn drop(&mut self)

Executes the destructor for this type.

fn pin_drop(self: Pin<&mut Self>)

🔬This is a nightly-only experimental API. (pin_ergonomics)

Execute the destructor for this type, but different to Drop::drop, it requires self to be pinned.