Struct Device

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pub struct Device { /* private fields */ }

Expand description

A V4L2 device.

Implementations§

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impl Device

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pub fn open<A: AsRef<Path>>(path: A) -> Result<Self>

Opens a V4L2 device file from the given path.

If the path does not refer to a V4L2 device node, an error will be returned.

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pub fn path(&self) -> Result<PathBuf>

Returns the path to the V4L2 device.

This will invoke readlink(2) on /proc/self/fd/N to find the path, so it will not work on FreeBSD or other Unix-likes that don’t expose a procfs with this functionality.

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pub fn capabilities(&self) -> Result<Capabilities>

Queries the device’s Capabilities.

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pub fn supported_buf_types(&self) -> BufTypes

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pub fn formats(&self, buf_type: BufType) -> FormatDescIter<'_> ⓘ

Enumerates the supported pixel formats of a stream.

buf_type must be one of VIDEO_CAPTURE, VIDEO_CAPTURE_MPLANE, VIDEO_OUTPUT, VIDEO_OUTPUT_MPLANE, VIDEO_OVERLAY, SDR_CAPTURE, SDR_OUTPUT, META_CAPTURE, or META_OUTPUT.

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pub fn frame_sizes(&self, pixel_format: PixelFormat) -> Result<FrameSizes>

Returns the supported frame sizes for a given pixel format.

§Errors

An ENOTTY error will be returned if pixel_format specifies a format that does not describe video data (for example, PixelFormat::UVC or other metadata formats).

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pub fn frame_intervals( &self, pixel_format: PixelFormat, width: u32, height: u32, ) -> Result<FrameIntervals>

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pub fn inputs(&self) -> InputIter<'_> ⓘ

Returns an iterator over the Inputs of the device.

§Errors

May return ENOTTY if the device is not an input device.

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pub fn outputs(&self) -> OutputIter<'_> ⓘ

Returns an iterator over the Outputs of the device.

§Errors

May return ENOTTY if the device is not an output device.

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pub fn controls(&self) -> ControlIter<'_> ⓘ

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pub fn enumerate_menu(&self, ctrl: &ControlDesc) -> TextMenuIter<'_> ⓘ

Returns an iterator over the valid values of a menu control.

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pub fn read_control_raw(&self, cid: Cid) -> Result<i32>

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pub fn write_control_raw(&mut self, cid: Cid, value: i32) -> Result<()>

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pub fn format(&self, buf_type: BufType) -> Result<Format>

Reads the stream format in use by buf_type.

The returned Format variant will match buf_type.

If no format is set, this returns EINVAL.

§Panics

This will panic if buf_type corresponds to a buffer type that hasn’t yet been implemented in Format.

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pub fn video_capture(self, format: PixFormat) -> Result<VideoCaptureDevice>

Puts the device into video capture mode and negotiates a pixel format.

§Format Negotiation

Generally, the driver is allowed to change most properties of the PixFormat, including the requested dimensions and the PixelFormat, if the provided value is not supported. However, it is not required to do so and may instead return EINVAL if the parameters are not supported. One example where this happens is with v4l2loopback.

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pub fn video_output(self, format: PixFormat) -> Result<VideoOutputDevice>

Puts the device into video output mode and negotiates a pixel format.

§Format Negotiation

Generally, the driver is allowed to change most properties of the PixFormat, including the requested dimensions and the PixelFormat, if the provided value is not supported. However, it is not required to do so and may instead return EINVAL if the parameters are not supported. One example where this happens is with v4l2loopback.

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