[−][src]Trait opencv::hub_prelude::VideoCaptureTrait

pub trait VideoCaptureTrait {
    pub fn as_raw_VideoCapture(&self) -> *const c_void;
    pub fn as_raw_mut_VideoCapture(&mut self) -> *mut c_void;

    pub fn open_file(
        &mut self, 
        filename: &str, 
        api_preference: i32
    ) -> Result<bool> { ... }
    pub fn open(&mut self, index: i32, api_preference: i32) -> Result<bool> { ... }
    pub fn is_opened(&self) -> Result<bool> { ... }
    pub fn release(&mut self) -> Result<()> { ... }
    pub fn grab(&mut self) -> Result<bool> { ... }
    pub fn retrieve(
        &mut self, 
        image: &mut dyn ToOutputArray, 
        flag: i32
    ) -> Result<bool> { ... }
    pub fn read(&mut self, image: &mut dyn ToOutputArray) -> Result<bool> { ... }
    pub fn set(&mut self, prop_id: i32, value: f64) -> Result<bool> { ... }
    pub fn get(&self, prop_id: i32) -> Result<f64> { ... }
    pub fn get_backend_name(&self) -> Result<String> { ... }
    pub fn set_exception_mode(&mut self, enable: bool) -> Result<()> { ... }
    pub fn get_exception_mode(&mut self) -> Result<bool> { ... }
}

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 @ref 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

Required methods

`pub fn as_raw_VideoCapture(&self) -> *const c_void`[src]

`pub fn as_raw_mut_VideoCapture(&mut self) -> *mut c_void`[src]

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Provided methods

`pub fn open_file(&mut self, filename: &str, api_preference: i32) -> Result<bool>`[src]

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

Parameters are same as the constructor VideoCapture(const String& filename, int apiPreference = CAP_ANY)

Returns

true if the file has been successfully opened

The method first calls VideoCapture::release to close the already opened file or camera.

C++ default parameters

api_preference: CAP_ANY

`pub fn open(&mut self, index: i32, api_preference: i32) -> Result<bool>`[src]

Opens a camera for video capturing

Parameters are same as the constructor VideoCapture(int index, int apiPreference = CAP_ANY)

Returns

true if the camera has been successfully opened.

The method first calls VideoCapture::release to close the already opened file or camera.

C++ default parameters

api_preference: CAP_ANY

`pub fn is_opened(&self) -> Result<bool>`[src]

Returns true if video capturing has been initialized already.

If the previous call to VideoCapture constructor or VideoCapture::open() succeeded, the method returns true.

`pub fn release(&mut self) -> Result<()>`[src]

Closes video file or capturing device.

The method is automatically called by subsequent VideoCapture::open and by VideoCapture destructor.

The C function also deallocates memory and clears *capture pointer.

`pub fn grab(&mut self) -> Result<bool>`[src]

Grabs the next frame from video file or capturing device.

Returns

true (non-zero) in the case of success.

The method/function grabs the next frame from video file or camera and returns true (non-zero) in the case of success.

The primary use of the function is in multi-camera environments, especially when the cameras do not have hardware synchronization. That is, you call VideoCapture::grab() for each camera and after that call the slower method VideoCapture::retrieve() to decode and get frame from each camera. This way the overhead on demosaicing or motion jpeg decompression etc. is eliminated and the retrieved frames from different cameras will be closer in time.

Also, when a connected camera is multi-head (for example, a stereo camera or a Kinect device), the correct way of retrieving data from it is to call VideoCapture::grab() first and then call VideoCapture::retrieve() one or more times with different values of the channel parameter.

@ref tutorial_kinect_openni

`pub fn retrieve( &mut self, image: &mut dyn ToOutputArray, flag: i32 ) -> Result<bool>`[src]

Decodes and returns the grabbed video frame.

Parameters

image:[out] the video frame is returned here. If no frames has been grabbed the image will be empty.
flag: it could be a frame index or a driver specific flag

Returns

false if no frames has been grabbed

The method decodes and returns the just grabbed frame. If no frames has been grabbed (camera has been disconnected, or there are no more frames in video file), the method returns false and the function returns an empty image (with %cv::Mat, test it with Mat::empty()).

C++ default parameters

flag: 0

`pub fn read(&mut self, image: &mut dyn ToOutputArray) -> Result<bool>`[src]

Grabs, decodes and returns the next video frame.

Parameters

image:[out] the video frame is returned here. If no frames has been grabbed the image will be empty.

Returns

false if no frames has been grabbed

The method/function combines VideoCapture::grab() and VideoCapture::retrieve() in one call. This is the most convenient method for reading video files or capturing data from decode and returns the just grabbed frame. If no frames has been grabbed (camera has been disconnected, or there are no more frames in video file), the method returns false and the function returns empty image (with %cv::Mat, test it with Mat::empty()).

Note: In @ref videoio_c "C API", functions cvRetrieveFrame() and cv.RetrieveFrame() return image stored inside the video capturing structure. It is not allowed to modify or release the image! You can copy the frame using cvCloneImage and then do whatever you want with the copy.

`pub fn set(&mut self, prop_id: i32, value: f64) -> Result<bool>`[src]

Sets a property in the VideoCapture.

Parameters

propId: Property identifier from cv::VideoCaptureProperties (eg. cv::CAP_PROP_POS_MSEC, cv::CAP_PROP_POS_FRAMES, ...) or one from @ref videoio_flags_others
value: Value of the property.

Returns

true if the property is supported by backend used by the VideoCapture instance.

Note: Even if it returns true this doesn't ensure that the property value has been accepted by the capture device. See note in VideoCapture::get()

`pub fn get(&self, prop_id: i32) -> Result<f64>`[src]

Returns the specified VideoCapture property

Parameters

propId: Property identifier from cv::VideoCaptureProperties (eg. cv::CAP_PROP_POS_MSEC, cv::CAP_PROP_POS_FRAMES, ...) or one from @ref videoio_flags_others

Returns

Value for the specified property. Value 0 is returned when querying a property that is not supported by the backend used by the VideoCapture instance.

Note: Reading / writing properties involves many layers. Some unexpected result might happens along this chain.

VideoCapture -> API Backend -> Operating System -> Device Driver -> Device Hardware

The returned value might be different from what really used by the device or it could be encoded using device dependent rules (eg. steps or percentage). Effective behaviour depends from device driver and API Backend

`pub fn get_backend_name(&self) -> Result<String>`[src]

Returns used backend API name

Note: Stream should be opened.

`pub fn set_exception_mode(&mut self, enable: bool) -> Result<()>`[src]

Switches exceptions mode

methods raise exceptions if not successful instead of returning an error code

`pub fn get_exception_mode(&mut self) -> Result<bool>`[src]

query if exception mode is active

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Implementors

`impl VideoCaptureTrait for VideoCapture`[src]

`pub fn as_raw_VideoCapture(&self) -> *const c_void`[src]

`pub fn as_raw_mut_VideoCapture(&mut self) -> *mut c_void`[src]

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[−][src]Trait opencv::hub_prelude::VideoCaptureTrait

Required methods

pub fn as_raw_VideoCapture(&self) -> *const c_void[src]

pub fn as_raw_mut_VideoCapture(&mut self) -> *mut c_void[src]

Provided methods

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

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

pub fn is_opened(&self) -> Result<bool>[src]

pub fn release(&mut self) -> Result<()>[src]

pub fn grab(&mut self) -> Result<bool>[src]

pub fn retrieve( &mut self, image: &mut dyn ToOutputArray, flag: i32) -> Result<bool>[src]

pub fn read(&mut self, image: &mut dyn ToOutputArray) -> Result<bool>[src]

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

pub fn get(&self, prop_id: i32) -> Result<f64>[src]

pub fn get_backend_name(&self) -> Result<String>[src]

pub fn set_exception_mode(&mut self, enable: bool) -> Result<()>[src]

pub fn get_exception_mode(&mut self) -> Result<bool>[src]

Implementors

impl VideoCaptureTrait for VideoCapture[src]

pub fn as_raw_VideoCapture(&self) -> *const c_void[src]

pub fn as_raw_mut_VideoCapture(&mut self) -> *mut c_void[src]

`pub fn as_raw_VideoCapture(&self) -> *const c_void`[src]

`pub fn as_raw_mut_VideoCapture(&mut self) -> *mut c_void`[src]

`pub fn open_file(&mut self, filename: &str, api_preference: i32) -> Result<bool>`[src]

`pub fn open(&mut self, index: i32, api_preference: i32) -> Result<bool>`[src]

`pub fn is_opened(&self) -> Result<bool>`[src]

`pub fn release(&mut self) -> Result<()>`[src]

`pub fn grab(&mut self) -> Result<bool>`[src]

`pub fn retrieve( &mut self, image: &mut dyn ToOutputArray, flag: i32 ) -> Result<bool>`[src]

`pub fn read(&mut self, image: &mut dyn ToOutputArray) -> Result<bool>`[src]

`pub fn set(&mut self, prop_id: i32, value: f64) -> Result<bool>`[src]

`pub fn get(&self, prop_id: i32) -> Result<f64>`[src]

`pub fn get_backend_name(&self) -> Result<String>`[src]

`pub fn set_exception_mode(&mut self, enable: bool) -> Result<()>`[src]

`pub fn get_exception_mode(&mut self) -> Result<bool>`[src]

`impl VideoCaptureTrait for VideoCapture`[src]

`pub fn as_raw_VideoCapture(&self) -> *const c_void`[src]

`pub fn as_raw_mut_VideoCapture(&mut self) -> *mut c_void`[src]