Expand description
Video I/O
Read and write video or images sequence with OpenCV
See also:
- [videoio_overview]
- Tutorials: [tutorial_table_of_content_app]
Flags for video I/O
Additional flags for video I/O API backends
Hardware-accelerated video decoding and encoding
C API for video I/O
iOS glue for video I/O
WinRT glue for video I/O
Query I/O API backends registry
Modules
Structs
- Class for video capturing from video files, image sequences or cameras.
- Video writer class.
Enums
- Video Acceleration type
- cv::VideoCapture API backends identifier.
- OBSENSOR (for Orbbec 3D-Sensor device/module )
- OBSENSOR stream generator
- OBSENSOR properties
- cv::VideoCapture generic properties identifier.
- cv::VideoWriter generic properties identifier.
Constants
- Android - not used
- Auto detect == 0
- Aravis SDK
- AVFoundation framework for iOS (OS X Lion will have the same API)
- Same value as CAP_FIREWIRE
- Same value as CAP_FIREWIRE
- DirectShow (via videoInput)
- Open and record video file or stream using the FFMPEG library
- Same value as CAP_FIREWIRE
- IEEE 1394 drivers
- Smartek Giganetix GigEVisionSDK
- gPhoto2 connection
- GStreamer
- Same value as CAP_FIREWIRE
- OpenCV Image Sequence (e.g. img_%02d.jpg)
- RealSense (former Intel Perceptual Computing SDK)
- Each pixel is a 16-bit integer. The value indicates the distance from an object to the camera’s XY plane or the Cartesian depth.
- Each pixel is a 16-bit integer. The value indicates the intensity of the reflected laser beam.
- Each pixel contains two 32-bit floating point values in the range of 0-1, representing the mapping of depth coordinates to the color coordinates.
- Intel MediaSDK
- Microsoft Media Foundation (via videoInput)
- For Orbbec 3D-Sensor device/module (Astra+, Femto)
- Data given from BGR stream generator
- Depth values in mm (CV_16UC1)
- Data given from IR stream generator(CV_16UC1)
- Built-in OpenCV MotionJPEG codec
- OpenNI (for Kinect)
- OpenNI2 (for Kinect)
- OpenNI2 (for Orbbec Astra)
- OpenNI2 (for Asus Xtion and Occipital Structure sensors)
- OpenNI (for Asus Xtion)
- Data given from RGB image generator
- Depth values in mm (CV_16UC1)
- Disparity in pixels (CV_8UC1)
- Disparity in pixels (CV_32FC1)
- Data given from RGB image generator
- Data given from IR image generator
- XYZ in meters (CV_32FC3)
- CV_8UC1
- Aperture. Can be readonly, depends on camera program.
- Automatically trigger frame capture if camera is configured with software trigger
- (read-only) Index of the first audio channel for .retrieve() calls. That audio channel number continues enumeration after video channels.
- (open, read) Alternative definition to bits-per-sample, but with clear handling of 32F / 32S
- (read-only) Audio position is measured in samples. Accurate audio sample timestamp of previous grabbed fragment. See CAP_PROP_AUDIO_SAMPLES_PER_SECOND and CAP_PROP_AUDIO_SHIFT_NSEC.
- (open, read) determined from file/codec input. If not specified, then selected audio sample rate is 44100
- (read only) Contains the time difference between the start of the audio stream and the video stream in nanoseconds. Positive value means that audio is started after the first video frame. Negative value means that audio is started before the first video frame.
- (open-only) Specify stream in multi-language media files, -1 - disable audio processing or microphone. Default value is -1.
- (open, read) Enables audio synchronization.
- (read-only) Number of audio channels in the selected audio stream (mono, stereo, etc)
- (read-only) Number of audio streams.
- DC1394: exposure control done by camera, user can adjust reference level using this feature.
- enable/ disable auto white-balance
- Current backend (enum VideoCaptureAPIs). Read-only property
- (read-only) Video bitrate in kbits/s
- Brightness of the image (only for those cameras that support).
- Video input or Channel Number (only for those cameras that support)
- Positive index indicates that returning extra data is supported by the video back end. This can be retrieved as cap.retrieve(data,
). E.g. When reading from a h264 encoded RTSP stream, the FFmpeg backend could return the SPS and/or PPS if available (if sent in reply to a DESCRIBE request), from calls to cap.retrieve(data, ). - (read-only) codec’s pixel format. 4-character code - see VideoWriter::fourcc . Subset of AV_PIX_FMT_* or -1 if unknown
- Contrast of the image (only for cameras).
- Boolean flags indicating whether images should be converted to RGB.
GStreamer note: The flag is ignored in case if custom pipeline is used. It’s user responsibility to interpret pipeline output. - set automatically when a value of the feature is set by the user.
- turn the feature off (not controlled manually nor automatically).
- Exposure (only for those cameras that support).
- Camera exposure program.
- Format of the %Mat objects (see Mat::type()) returned by VideoCapture::retrieve(). Set value -1 to fetch undecoded RAW video streams (as Mat 8UC1).
- 4-character code of codec. see VideoWriter::fourcc .
- Frame rate.
- Number of frames in the video file.
- Height of the frames in the video stream.
- (read-only) FFmpeg back-end only - Frame type ascii code (73 = ‘I’, 80 = ‘P’, 66 = ‘B’ or 63 = ‘?’ if unknown) of the most recently read frame.
- Width of the frames in the video stream.
- Gain of the image (only for those cameras that support).
- Collect messages with details.
- Readonly, returns (const char *).
- Capture only preview from liveview mode.
- Trigger, only by set. Reload camera settings.
- Reload all settings on set.
- Readonly, returns (const char *).
- Default is 1
- Hue of the image (only for cameras).
- (open-only) Hardware acceleration type (see #VideoAccelerationType). Setting supported only via
paramsparameter in cv::VideoCapture constructor / .open() method. Default value is backend-specific. - (open-only) If non-zero, create new OpenCL context and bind it to current thread. The OpenCL context created with Video Acceleration context attached it (if not attached yet) for optimized GPU data copy between HW accelerated decoder and cv::UMat.
- (open-only) Hardware device index (select GPU if multiple available). Device enumeration is acceleration type specific.
- FFmpeg back-end only - Indicates whether the Last Raw Frame (LRF), output from VideoCapture::read() when VideoCapture is initialized with VideoCapture::open(CAP_FFMPEG, {CAP_PROP_FORMAT, -1}) or VideoCapture::set(CAP_PROP_FORMAT,-1) is called before the first call to VideoCapture::read(), contains encoded data for a key frame.
- Backend-specific value indicating the current capture mode.
- (open-only) Set the maximum number of threads to use. Use 0 to use as many threads as CPU cores (applicable for FFmpeg back-end only).
- In mm
- In pixels
- In mm
- Flag that synchronizes the remapping depth map to image map by changing depth generator’s view point (if the flag is “on”) or sets this view point to its normal one (if the flag is “off”).
- (open-only) timeout in milliseconds for opening a video capture (applicable for FFmpeg and GStreamer back-ends only)
- if true - rotates output frames of CvCapture considering video file’s metadata (applicable for FFmpeg and AVFoundation back-ends only) (https://github.com/opencv/opencv/issues/15499)
- (read-only) Frame rotation defined by stream meta (applicable for FFmpeg and AVFoundation back-ends only)
- Relative position of the video file: 0=start of the film, 1=end of the film.
- 0-based index of the frame to be decoded/captured next.
- Current position of the video file in milliseconds.
- Horizontal binning factor.
- Vertical binning factor.
- Horizontal sub-sampling of the image.
- Vertical sub-sampling of the image.
- FrameStartTriggerMode: Determines how a frame is initiated.
- IP for enable multicast master mode. 0 for disable multicast.
- Pixel format.
- (open-only) timeout in milliseconds for reading from a video capture (applicable for FFmpeg and GStreamer back-ends only)
- Rectification flag for stereo cameras (note: only supported by DC1394 v 2.x backend currently).
- Sample aspect ratio: num/den (den)
- Sample aspect ratio: num/den (num)
- Saturation of the image (only for cameras).
- Pop up video/camera filter dialog (note: only supported by DSHOW backend currently. The property value is ignored)
- Exposure speed. Can be readonly, depends on camera program.
- (open-only) Specify video stream, 0-based index. Use -1 to disable video stream from file or IP cameras. Default value is 0.
- (read-only) Number of video channels
- Enter liveview mode.
- white-balance color temperature
- Currently unsupported.
- Acquisition buffer size in buffer_size_unit. Default bytes.
- Acquisition buffer size unit in bytes. Default 1. E.g. Value 1024 means that buffer_size is in KiBytes.
- Sets number of frames acquired by burst. This burst is used only if trigger is set to FrameBurstStart.
- Type of sensor frames timing.
- Number of buffers to commit to low level.
- Acquisition transport buffer size in bytes.
- Automatic exposure/gain.
- Average intensity of output signal AEAG should achieve(in %).
- Automatic exposure/gain ROI Height.
- Automatic exposure/gain ROI offset X.
- Automatic exposure/gain ROI offset Y.
- Automatic exposure/gain ROI Width.
- Maximum limit of exposure in AEAG procedure.
- Maximum limit of gain in AEAG procedure.
- Enable applying of CMS profiles to xiGetImage (see XI_PRM_INPUT_CMS_PROFILE, XI_PRM_OUTPUT_CMS_PROFILE).
- Automatic bandwidth calculation.
- Automatic white balance.
- Calculate and returns available interface bandwidth(int Megabits).
- Horizontal Binning - number of horizontal photo-sensitive cells to combine together.
- Binning pattern type.
- Binning engine selector.
- Vertical Binning - number of vertical photo-sensitive cells to combine together.
- Correction of bad pixels.
- Queue of field/frame buffers.
- Data move policy.
- Color Correction Matrix element [0][0].
- Color Correction Matrix element [0][1].
- Color Correction Matrix element [0][2].
- Color Correction Matrix element [0][3].
- Color Correction Matrix element [1][0].
- Color Correction Matrix element [1][1].
- Color Correction Matrix element [1][2].
- Color Correction Matrix element [1][3].
- Color Correction Matrix element [2][0].
- Color Correction Matrix element [2][1].
- Color Correction Matrix element [2][2].
- Color Correction Matrix element [2][3].
- Color Correction Matrix element [3][0].
- Color Correction Matrix element [3][1].
- Color Correction Matrix element [3][2].
- Color Correction Matrix element [3][3].
- Camera sensor temperature.
- Mode of color management system.
- Returns color filter array type of RAW data.
- Correction of column FPN.
- Start camera cooling.
- Select counter.
- Counter status.
- Output data format.
- Enable/Disable debounce to selected GPI.
- Debounce polarity (pol = 1 t0 - falling edge, t1 - rising edge).
- Debounce time (x * 10us).
- Debounce time (x * 10us).
- Set debug level.
- Horizontal Decimation - horizontal sub-sampling of the image - reduces the horizontal resolution of the image by the specified vertical decimation factor.
- Decimation pattern type.
- Decimation engine selector.
- Vertical Decimation - vertical sub-sampling of the image - reduces the vertical resolution of the image by the specified vertical decimation factor.
- Set default Color Correction Matrix.
- Returns device model id.
- Resets the camera to default state.
- Returns device serial number.
- Change image resolution by binning or skipping.
- Change image downsampling type.
- Exposure time in microseconds.
- Sets the number of times of exposure in one frame.
- Exposure priority (0.5 - exposure 50%, gain 50%).
- Setting of key enables file operations on some cameras.
- File number.
- Size of file.
- Define framerate in Hz.
- Size of free camera FFS.
- Gain in dB.
- Gain selector for parameter Gain allows to select different type of gains.
- Chromaticity gamma.
- Luminosity gamma.
- Get general purpose level.
- Set general purpose input mode.
- Selects general purpose input.
- Set general purpose output mode.
- Selects general purpose output.
- Enable High Dynamic Range feature.
- The number of kneepoints in the PWLR.
- Position of first kneepoint(in % of XI_PRM_EXPOSURE).
- Position of second kneepoint (in % of XI_PRM_EXPOSURE).
- Height of the Image provided by the device (in pixels).
- Camera housing back side temperature.
- Camera housing temperature.
- Returns hardware revision number.
- Last image black level counts. Can be used for Offline processing to recall it.
- bitdepth of data returned by function xiGetImage.
- Output data format.
- The alpha channel of RGB32 output image format.
- Returns 1 for color cameras.
- Buffer size in bytes sufficient for output image returned by xiGetImage.
- Returns 1 for cameras that support cooling.
- Returns 1 if camera connected and works properly.
- Value of first kneepoint (% of sensor saturation).
- Value of second kneepoint (% of sensor saturation).
- Define camera signalling LED functionality.
- Selects camera signalling LED.
- Current lens aperture value in stops. Examples: 2.8, 4, 5.6, 8, 11.
- Allows access to lens feature value currently selected by XI_PRM_LENS_FEATURE_SELECTOR.
- Selects the current feature which is accessible by XI_PRM_LENS_FEATURE.
- Lens focal distance in mm.
- Lens focus distance in cm.
- Moves lens focus motor by steps set in XI_PRM_LENS_FOCUS_MOVEMENT_VALUE.
- Lens current focus movement value to be used by XI_PRM_LENS_FOCUS_MOVE in motor steps.
- Status of lens control interface. This shall be set to XI_ON before any Lens operations.
- Set/get bandwidth(datarate)(in Megabits).
- Activates LUT.
- Control the index (offset) of the coefficient to access in the LUT.
- Value at entry LUTIndex of the LUT.
- Calculates White Balance(must be called during acquisition).
- Horizontal offset from the origin to the area of interest (in pixels).
- Vertical offset from the origin to the area of interest (in pixels).
- Device output data bit depth.
- Device output data packing (or grouping) enabled. Packing could be enabled if output_data_bit_depth > 8 and packing capability is available.
- Data packing type. Some cameras supports only specific packing type.
- GetImage returns most recent frame.
- Activates/deactivates Region selected by Region Selector.
- Selects Region in Multiple ROI which parameters are set by width, height, … ,region mode.
- Correction of row FPN.
- Camera sensor board temperature.
- Sensor clock frequency in Hz.
- Sensor clock frequency index. Sensor with selected frequencies have possibility to set the frequency only by this index.
- Sensor output data bit depth.
- Selects the current feature which is accessible by XI_PRM_SENSOR_FEATURE_VALUE.
- Allows access to sensor feature value currently selected by XI_PRM_SENSOR_FEATURE_SELECTOR.
- Current sensor mode. Allows to select sensor mode by one integer. Setting of this parameter affects: image dimensions and downsampling.
- Number of output channels from sensor used for data transfer.
- Number of taps.
- Sharpness Strength.
- Change sensor shutter type(CMOS sensor).
- Set sensor target temperature for cooling.
- Selects which test pattern type is generated by the selected generator.
- Selects which test pattern generator is controlled by the TestPattern feature.
- Image capture timeout in milliseconds.
- Current format of pixels on transport layer.
- Specifies the delay in microseconds (us) to apply after the trigger reception before activating it.
- Selects the type of trigger.
- Generates an internal trigger. PRM_TRG_SOURCE must be set to TRG_SOFTWARE.
- Defines source of trigger.
- Defines how time stamp reset engine will be armed.
- Defines which source will be used for timestamp reset. Writing this parameter will trigger settings of engine (arming).
- Size of used camera FFS.
- White balance blue coefficient.
- White balance green coefficient.
- White balance red coefficient.
- Width of the Image provided by the device (in pixels).
- PvAPI, Prosilica GigE SDK
- 2 out of 4 decimation
- 2 out of 8 decimation
- 2 out of 16 decimation
- Off
- FixedRate
- Freerun
- Software
- SyncIn1
- SyncIn2
- Bayer8
- Bayer16
- Bgr24
- Bgra32
- Mono8
- Mono16
- Rgb24
- Rgba32
- QuickTime (obsolete, removed)
- Synonym for CAP_INTELPERC
- uEye Camera API
- Unicap drivers (obsolete, removed)
- V4L/V4L2 capturing support
- Same as CAP_V4L
- Video For Windows (obsolete, removed)
- Microsoft Windows Runtime using Media Foundation
- XIMEA Camera API
- XINE engine (Linux)
- Defaults to CV_8U.
- (Read-only): Size of just encoded video frame. Note that the encoding order may be different from representation order.
- (open-only) Hardware acceleration type (see #VideoAccelerationType). Setting supported only via
paramsparameter in VideoWriter constructor / .open() method. Default value is backend-specific. - (open-only) If non-zero, create new OpenCL context and bind it to current thread. The OpenCL context created with Video Acceleration context attached it (if not attached yet) for optimized GPU data copy between cv::UMat and HW accelerated encoder.
- (open-only) Hardware device index (select GPU if multiple available). Device enumeration is acceleration type specific.
- If it is not zero, the encoder will expect and encode color frames, otherwise it will work with grayscale frames.
- Number of stripes for parallel encoding. -1 for auto detection.
- Current quality (0..100%) of the encoded videostream. Can be adjusted dynamically in some codecs.
- Prefer to use H/W acceleration. If no one supported, then fallback to software processing.
- DirectX 11
- libmfx (Intel MediaSDK/oneVPL)
- Do not require any specific H/W acceleration, prefer software processing. Reading of this value means that special H/W accelerated handling is not added or not detected by OpenCV.
- VAAPI
Traits
- Mutable methods for crate::videoio::VideoCapture
- Constant methods for crate::videoio::VideoCapture
- Mutable methods for crate::videoio::VideoWriter
- Constant methods for crate::videoio::VideoWriter
Functions
- Returns backend API name or “UnknownVideoAPI(xxx)”
- Returns list of all available backends
- Returns description and ABI/API version of videoio plugin’s camera interface
- Returns list of available backends which works via
cv::VideoCapture(int index) - Returns description and ABI/API version of videoio plugin’s stream capture interface
- Returns list of available backends which works via
cv::VideoCapture(filename) - Returns description and ABI/API version of videoio plugin’s writer interface
- Returns list of available backends which works via
cv::VideoWriter() - Returns true if backend is available
- Returns true if backend is built in (false if backend is used as plugin)