Struct VideoCapture

pub struct VideoCapture { /* private fields */ }

Class for video capturing from video files, image sequences or cameras.

The class provides C++ API for capturing video from cameras or for reading video files and image sequences.

Here is how the class can be used: @include samples/cpp/videocapture_basic.cpp

Note: In [videoio_c] “C API” the black-box structure CvCapture is used instead of %VideoCapture.

Note:

• (C++) A basic sample on using the %VideoCapture interface can be found at OPENCV_SOURCE_CODE/samples/cpp/videocapture_starter.cpp
• (Python) A basic sample on using the %VideoCapture interface can be found at OPENCV_SOURCE_CODE/samples/python/video.py
• (Python) A multi threaded video processing sample can be found at OPENCV_SOURCE_CODE/samples/python/video_threaded.py
• (Python) %VideoCapture sample showcasing some features of the Video4Linux2 backend OPENCV_SOURCE_CODE/samples/python/video_v4l2.py

Implementations

impl VideoCapture

pub fn default() -> Result<VideoCapture>

Default constructor

Note: In [videoio_c] “C API”, when you finished working with video, release CvCapture structure with cvReleaseCapture(), or use Ptr<CvCapture> that calls cvReleaseCapture() automatically in the destructor.

pub fn from_file(filename: &str, api_preference: i32) -> Result<VideoCapture>

Default constructor

Note: In [videoio_c] “C API”, when you finished working with video, release CvCapture structure with cvReleaseCapture(), or use Ptr<CvCapture> that calls cvReleaseCapture() automatically in the destructor.

Overloaded parameters

Opens a video file or a capturing device or an IP video stream for video capturing with API Preference

Parameters

• filename: it can be:

• name of video file (eg. video.avi)
• or image sequence (eg. img_%02d.jpg, which will read samples like img_00.jpg, img_01.jpg, img_02.jpg, ...)
• or URL of video stream (eg. protocol://host:port/script_name?script_params|auth)
• or GStreamer pipeline string in gst-launch tool format in case if GStreamer is used as backend Note that each video stream or IP camera feed has its own URL scheme. Please refer to the documentation of source stream to know the right URL.

• apiPreference: preferred Capture API backends to use. Can be used to enforce a specific reader implementation if multiple are available: e.g. cv::CAP_FFMPEG or cv::CAP_IMAGES or cv::CAP_DSHOW.

See also

cv::VideoCaptureAPIs

C++ default parameters

• api_preference: CAP_ANY

pub fn from_file_def(filename: &str) -> Result<VideoCapture>

@overload Opens a video file or a capturing device or an IP video stream for video capturing with API Preference

Parameters

• filename: it can be:

• name of video file (eg. video.avi)
• or image sequence (eg. img_%02d.jpg, which will read samples like img_00.jpg, img_01.jpg, img_02.jpg, ...)
• or URL of video stream (eg. protocol://host:port/script_name?script_params|auth)
• or GStreamer pipeline string in gst-launch tool format in case if GStreamer is used as backend Note that each video stream or IP camera feed has its own URL scheme. Please refer to the documentation of source stream to know the right URL.

• apiPreference: preferred Capture API backends to use. Can be used to enforce a specific reader implementation if multiple are available: e.g. cv::CAP_FFMPEG or cv::CAP_IMAGES or cv::CAP_DSHOW.

See also

cv::VideoCaptureAPIs

Note

This alternative version of [from_file] function uses the following default values for its arguments:

• api_preference: CAP_ANY

pub fn from_file_with_params( filename: &str, api_preference: i32, params: &Vector<i32>, ) -> Result<VideoCapture>

Default constructor

Note: In [videoio_c] “C API”, when you finished working with video, release CvCapture structure with cvReleaseCapture(), or use Ptr<CvCapture> that calls cvReleaseCapture() automatically in the destructor.

Overloaded parameters

Opens a video file or a capturing device or an IP video stream for video capturing with API Preference and parameters

The params parameter allows to specify extra parameters encoded as pairs (paramId_1, paramValue_1, paramId_2, paramValue_2, ...). See cv::VideoCaptureProperties

pub fn new(index: i32, api_preference: i32) -> Result<VideoCapture>

Default constructor

Note: In [videoio_c] “C API”, when you finished working with video, release CvCapture structure with cvReleaseCapture(), or use Ptr<CvCapture> that calls cvReleaseCapture() automatically in the destructor.

Overloaded parameters

Opens a camera for video capturing

Parameters

• index: id of the video capturing device to open. To open default camera using default backend just pass 0. (to backward compatibility usage of camera_id + domain_offset (CAP_*) is valid when apiPreference is CAP_ANY)
• apiPreference: preferred Capture API backends to use. Can be used to enforce a specific reader implementation if multiple are available: e.g. cv::CAP_DSHOW or cv::CAP_MSMF or cv::CAP_V4L.

See also

cv::VideoCaptureAPIs

C++ default parameters

• api_preference: CAP_ANY

pub fn new_def(index: i32) -> Result<VideoCapture>

@overload Opens a camera for video capturing

Parameters

• index: id of the video capturing device to open. To open default camera using default backend just pass 0. (to backward compatibility usage of camera_id + domain_offset (CAP_*) is valid when apiPreference is CAP_ANY)
• apiPreference: preferred Capture API backends to use. Can be used to enforce a specific reader implementation if multiple are available: e.g. cv::CAP_DSHOW or cv::CAP_MSMF or cv::CAP_V4L.

See also

cv::VideoCaptureAPIs

Note

This alternative version of [new] function uses the following default values for its arguments:

• api_preference: CAP_ANY

pub fn new_with_params( index: i32, api_preference: i32, params: &Vector<i32>, ) -> Result<VideoCapture>

Default constructor

Note: In [videoio_c] “C API”, when you finished working with video, release CvCapture structure with cvReleaseCapture(), or use Ptr<CvCapture> that calls cvReleaseCapture() automatically in the destructor.

Overloaded parameters

Opens a camera for video capturing with API Preference and parameters

The params parameter allows to specify extra parameters encoded as pairs (paramId_1, paramValue_1, paramId_2, paramValue_2, ...). See cv::VideoCaptureProperties

pub fn new_1( source: &Ptr<IStreamReader>, api_preference: i32, params: &Vector<i32>, ) -> Result<VideoCapture>

Default constructor

Note: In [videoio_c] “C API”, when you finished working with video, release CvCapture structure with cvReleaseCapture(), or use Ptr<CvCapture> that calls cvReleaseCapture() automatically in the destructor.

Overloaded parameters

Opens a video using data stream.

The params parameter allows to specify extra parameters encoded as pairs (paramId_1, paramValue_1, paramId_2, paramValue_2, ...). See cv::VideoCaptureProperties

pub fn wait_any( streams: &Vector<VideoCapture>, ready_index: &mut Vector<i32>, timeout_ns: i64, ) -> Result<bool>

Wait for ready frames from VideoCapture.

Parameters

• streams: input video streams
• readyIndex: stream indexes with grabbed frames (ready to use .retrieve() to fetch actual frame)
• timeoutNs: number of nanoseconds (0 - infinite)

Returns

true if streamReady is not empty

@throws Exception %Exception on stream errors (check .isOpened() to filter out malformed streams) or VideoCapture type is not supported

The primary use of the function is in multi-camera environments. The method fills the ready state vector, grabs video frame, if camera is ready.

After this call use VideoCapture::retrieve() to decode and fetch frame data.

C++ default parameters

• timeout_ns: 0

pub fn wait_any_def( streams: &Vector<VideoCapture>, ready_index: &mut Vector<i32>, ) -> Result<bool>

Wait for ready frames from VideoCapture.

Parameters

• streams: input video streams
• readyIndex: stream indexes with grabbed frames (ready to use .retrieve() to fetch actual frame)
• timeoutNs: number of nanoseconds (0 - infinite)

Returns

true if streamReady is not empty

@throws Exception %Exception on stream errors (check .isOpened() to filter out malformed streams) or VideoCapture type is not supported

The primary use of the function is in multi-camera environments. The method fills the ready state vector, grabs video frame, if camera is ready.

After this call use VideoCapture::retrieve() to decode and fetch frame data.

Note

This alternative version of VideoCapture::wait_any function uses the following default values for its arguments:

• timeout_ns: 0

Trait Implementations

impl Boxed for VideoCapture

unsafe fn from_raw( ptr: <VideoCapture as OpenCVFromExtern>::ExternReceive, ) -> Self

Wrap the specified raw pointer

fn into_raw(self) -> <VideoCapture as OpenCVTypeExternContainer>::ExternSendMut

Return the underlying raw pointer while consuming this wrapper.

fn as_raw(&self) -> <VideoCapture as OpenCVTypeExternContainer>::ExternSend

Return the underlying raw pointer.

fn as_raw_mut( &mut self, ) -> <VideoCapture as OpenCVTypeExternContainer>::ExternSendMut

Return the underlying mutable raw pointer

impl Debug for VideoCapture

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

Formats the value using the given formatter.

impl Drop for VideoCapture

fn drop(&mut self)

Executes the destructor for this type.

impl VideoCaptureTrait for VideoCapture

fn as_raw_mut_VideoCapture(&mut self) -> *mut c_void

fn open_file(&mut self, filename: &str, api_preference: i32) -> Result<bool>

Opens a video file or a capturing device or an IP video stream for video capturing.

fn open_file_def(&mut self, filename: &str) -> Result<bool>

Opens a video file or a capturing device or an IP video stream for video capturing.

fn open_file_with_params( &mut self, filename: &str, api_preference: i32, params: &Vector<i32>, ) -> Result<bool>

Opens a video file or a capturing device or an IP video stream for video capturing with API Preference and parameters

fn open(&mut self, index: i32, api_preference: i32) -> Result<bool>

Opens a camera for video capturing

fn open_def(&mut self, index: i32) -> Result<bool>

Opens a camera for video capturing

fn open_with_params( &mut self, index: i32, api_preference: i32, params: &Vector<i32>, ) -> Result<bool>

Opens a camera for video capturing with API Preference and parameters

fn open_1( &mut self, source: &Ptr<IStreamReader>, api_preference: i32, params: &Vector<i32>, ) -> Result<bool>

Opens a video using data stream.

fn release(&mut self) -> Result<()>

Closes video file or capturing device.

fn grab(&mut self) -> Result<bool>

Grabs the next frame from video file or capturing device.

fn retrieve( &mut self, image: &mut impl ToOutputArray, flag: i32, ) -> Result<bool>

Decodes and returns the grabbed video frame.

fn retrieve_def(&mut self, image: &mut impl ToOutputArray) -> Result<bool>

Decodes and returns the grabbed video frame.

fn read(&mut self, image: &mut impl ToOutputArray) -> Result<bool>

Grabs, decodes and returns the next video frame.

fn set(&mut self, prop_id: i32, value: f64) -> Result<bool>

Sets a property in the VideoCapture.

fn set_exception_mode(&mut self, enable: bool) -> Result<()>

Switches exceptions mode

impl VideoCaptureTraitConst for VideoCapture

fn as_raw_VideoCapture(&self) -> *const c_void

fn is_opened(&self) -> Result<bool>

Returns true if video capturing has been initialized already.

fn get(&self, prop_id: i32) -> Result<f64>

Returns the specified VideoCapture property

fn get_backend_name(&self) -> Result<String>

Returns used backend API name

fn get_exception_mode(&self) -> Result<bool>

query if exception mode is active

impl Send for VideoCapture