Flags for video I/O

Enumerations
enum	cv::VideoCaptureAPIs {   cv::CAP_ANY = 0,   cv::CAP_VFW = 200,   cv::CAP_V4L = 200,   cv::CAP_V4L2 = CAP_V4L,   cv::CAP_FIREWIRE = 300,   cv::CAP_FIREWARE = CAP_FIREWIRE,   cv::CAP_IEEE1394 = CAP_FIREWIRE,   cv::CAP_DC1394 = CAP_FIREWIRE,   cv::CAP_CMU1394 = CAP_FIREWIRE,   cv::CAP_QT = 500,   cv::CAP_UNICAP = 600,   cv::CAP_DSHOW = 700,   cv::CAP_PVAPI = 800,   cv::CAP_OPENNI = 900,   cv::CAP_OPENNI_ASUS = 910,   cv::CAP_ANDROID = 1000,   cv::CAP_XIAPI = 1100,   cv::CAP_AVFOUNDATION = 1200,   cv::CAP_GIGANETIX = 1300,   cv::CAP_MSMF = 1400,   cv::CAP_WINRT = 1410,   cv::CAP_INTELPERC = 1500,   cv::CAP_REALSENSE = 1500,   cv::CAP_OPENNI2 = 1600,   cv::CAP_OPENNI2_ASUS = 1610,   cv::CAP_OPENNI2_ASTRA = 1620,   cv::CAP_GPHOTO2 = 1700,   cv::CAP_GSTREAMER = 1800,   cv::CAP_FFMPEG = 1900,   cv::CAP_IMAGES = 2000,   cv::CAP_ARAVIS = 2100,   cv::CAP_OPENCV_MJPEG = 2200,   cv::CAP_INTEL_MFX = 2300,   cv::CAP_XINE = 2400,   cv::CAP_UEYE = 2500,   cv::CAP_OBSENSOR = 2600 }
	cv::VideoCapture API backends identifier. More...
enum	cv::VideoCaptureProperties {   cv::CAP_PROP_POS_MSEC =0,   cv::CAP_PROP_POS_FRAMES =1,   cv::CAP_PROP_POS_AVI_RATIO =2,   cv::CAP_PROP_FRAME_WIDTH =3,   cv::CAP_PROP_FRAME_HEIGHT =4,   cv::CAP_PROP_FPS =5,   cv::CAP_PROP_FOURCC =6,   cv::CAP_PROP_FRAME_COUNT =7,   cv::CAP_PROP_FORMAT =8,   cv::CAP_PROP_MODE =9,   cv::CAP_PROP_BRIGHTNESS =10,   cv::CAP_PROP_CONTRAST =11,   cv::CAP_PROP_SATURATION =12,   cv::CAP_PROP_HUE =13,   cv::CAP_PROP_GAIN =14,   cv::CAP_PROP_EXPOSURE =15,   cv::CAP_PROP_CONVERT_RGB =16,   cv::CAP_PROP_WHITE_BALANCE_BLUE_U =17,   cv::CAP_PROP_RECTIFICATION =18,   cv::CAP_PROP_MONOCHROME =19,   cv::CAP_PROP_SHARPNESS =20,   cv::CAP_PROP_AUTO_EXPOSURE =21,   cv::CAP_PROP_GAMMA =22,   cv::CAP_PROP_TEMPERATURE =23,   cv::CAP_PROP_TRIGGER =24,   cv::CAP_PROP_TRIGGER_DELAY =25,   cv::CAP_PROP_WHITE_BALANCE_RED_V =26,   cv::CAP_PROP_ZOOM =27,   cv::CAP_PROP_FOCUS =28,   cv::CAP_PROP_GUID =29,   cv::CAP_PROP_ISO_SPEED =30,   cv::CAP_PROP_BACKLIGHT =32,   cv::CAP_PROP_PAN =33,   cv::CAP_PROP_TILT =34,   cv::CAP_PROP_ROLL =35,   cv::CAP_PROP_IRIS =36,   cv::CAP_PROP_SETTINGS =37,   cv::CAP_PROP_BUFFERSIZE =38,   cv::CAP_PROP_AUTOFOCUS =39,   cv::CAP_PROP_SAR_NUM =40,   cv::CAP_PROP_SAR_DEN =41,   cv::CAP_PROP_BACKEND =42,   cv::CAP_PROP_CHANNEL =43,   cv::CAP_PROP_AUTO_WB =44,   cv::CAP_PROP_WB_TEMPERATURE =45,   cv::CAP_PROP_CODEC_PIXEL_FORMAT =46,   cv::CAP_PROP_BITRATE =47,   cv::CAP_PROP_ORIENTATION_META =48,   cv::CAP_PROP_ORIENTATION_AUTO =49,   cv::CAP_PROP_HW_ACCELERATION =50,   cv::CAP_PROP_HW_DEVICE =51,   cv::CAP_PROP_HW_ACCELERATION_USE_OPENCL =52,   cv::CAP_PROP_OPEN_TIMEOUT_MSEC =53,   cv::CAP_PROP_READ_TIMEOUT_MSEC =54,   cv::CAP_PROP_STREAM_OPEN_TIME_USEC =55,   cv::CAP_PROP_VIDEO_TOTAL_CHANNELS = 56,   cv::CAP_PROP_VIDEO_STREAM = 57,   cv::CAP_PROP_AUDIO_STREAM = 58,   cv::CAP_PROP_AUDIO_POS = 59,   cv::CAP_PROP_AUDIO_SHIFT_NSEC = 60,   cv::CAP_PROP_AUDIO_DATA_DEPTH = 61,   cv::CAP_PROP_AUDIO_SAMPLES_PER_SECOND = 62,   cv::CAP_PROP_AUDIO_BASE_INDEX = 63,   cv::CAP_PROP_AUDIO_TOTAL_CHANNELS = 64,   cv::CAP_PROP_AUDIO_TOTAL_STREAMS = 65,   cv::CAP_PROP_AUDIO_SYNCHRONIZE = 66,   cv::CAP_PROP_LRF_HAS_KEY_FRAME = 67,   cv::CAP_PROP_CODEC_EXTRADATA_INDEX = 68,   cv::CAP_PROP_FRAME_TYPE = 69,   cv::CAP_PROP_N_THREADS = 70 }
	cv::VideoCapture generic properties identifier. More...
enum	cv::VideoWriterProperties {   cv::VIDEOWRITER_PROP_QUALITY = 1,   cv::VIDEOWRITER_PROP_FRAMEBYTES = 2,   cv::VIDEOWRITER_PROP_NSTRIPES = 3,   cv::VIDEOWRITER_PROP_IS_COLOR = 4,   cv::VIDEOWRITER_PROP_DEPTH = 5,   cv::VIDEOWRITER_PROP_HW_ACCELERATION = 6,   cv::VIDEOWRITER_PROP_HW_DEVICE = 7,   cv::VIDEOWRITER_PROP_HW_ACCELERATION_USE_OPENCL = 8 }
	cv::VideoWriter generic properties identifier. More...

Detailed Description

Enumeration Type Documentation

VideoCaptureAPIs

enum cv::VideoCaptureAPIs

#include <opencv2/videoio.hpp>

cv::VideoCapture API backends identifier.

Select preferred API for a capture object. To be used in the VideoCapture::VideoCapture() constructor or VideoCapture::open()

Note

• Backends are available only if they have been built with your OpenCV binaries. See Video I/O with OpenCV Overview for more information.
• Microsoft Media Foundation backend tries to use hardware accelerated transformations if possible. Environment flag "OPENCV_VIDEOIO_MSMF_ENABLE_HW_TRANSFORMS" set to 0 disables it and may improve initialization time. More details: https://learn.microsoft.com/en-us/windows/win32/medfound/mf-readwrite-enable-hardware-transforms

Enumerator
CAP_ANY  Python: cv.CAP_ANY	Auto detect == 0.
CAP_VFW  Python: cv.CAP_VFW	Video For Windows (obsolete, removed)
CAP_V4L  Python: cv.CAP_V4L	V4L/V4L2 capturing support.
CAP_V4L2  Python: cv.CAP_V4L2	Same as CAP_V4L.
CAP_FIREWIRE  Python: cv.CAP_FIREWIRE	IEEE 1394 drivers.
CAP_FIREWARE  Python: cv.CAP_FIREWARE	Same value as CAP_FIREWIRE.
CAP_IEEE1394  Python: cv.CAP_IEEE1394	Same value as CAP_FIREWIRE.
CAP_DC1394  Python: cv.CAP_DC1394	Same value as CAP_FIREWIRE.
CAP_CMU1394  Python: cv.CAP_CMU1394	Same value as CAP_FIREWIRE.
CAP_QT  Python: cv.CAP_QT	QuickTime (obsolete, removed)
CAP_UNICAP  Python: cv.CAP_UNICAP	Unicap drivers (obsolete, removed)
CAP_DSHOW  Python: cv.CAP_DSHOW	DirectShow (via videoInput)
CAP_PVAPI  Python: cv.CAP_PVAPI	PvAPI, Prosilica GigE SDK.
CAP_OPENNI  Python: cv.CAP_OPENNI	OpenNI (for Kinect)
CAP_OPENNI_ASUS  Python: cv.CAP_OPENNI_ASUS	OpenNI (for Asus Xtion)
CAP_ANDROID  Python: cv.CAP_ANDROID	Android - not used.
CAP_XIAPI  Python: cv.CAP_XIAPI	XIMEA Camera API.
CAP_AVFOUNDATION  Python: cv.CAP_AVFOUNDATION	AVFoundation framework for iOS (OS X Lion will have the same API)
CAP_GIGANETIX  Python: cv.CAP_GIGANETIX	Smartek Giganetix GigEVisionSDK.
CAP_MSMF  Python: cv.CAP_MSMF	Microsoft Media Foundation (via videoInput). See platform specific notes above.
CAP_WINRT  Python: cv.CAP_WINRT	Microsoft Windows Runtime using Media Foundation.
CAP_INTELPERC  Python: cv.CAP_INTELPERC	RealSense (former Intel Perceptual Computing SDK)
CAP_REALSENSE  Python: cv.CAP_REALSENSE	Synonym for CAP_INTELPERC.
CAP_OPENNI2  Python: cv.CAP_OPENNI2	OpenNI2 (for Kinect)
CAP_OPENNI2_ASUS  Python: cv.CAP_OPENNI2_ASUS	OpenNI2 (for Asus Xtion and Occipital Structure sensors)
CAP_OPENNI2_ASTRA  Python: cv.CAP_OPENNI2_ASTRA	OpenNI2 (for Orbbec Astra)
CAP_GPHOTO2  Python: cv.CAP_GPHOTO2	gPhoto2 connection
CAP_GSTREAMER  Python: cv.CAP_GSTREAMER	GStreamer.
CAP_FFMPEG  Python: cv.CAP_FFMPEG	Open and record video file or stream using the FFMPEG library.
CAP_IMAGES  Python: cv.CAP_IMAGES	OpenCV Image Sequence (e.g. img_%02d.jpg)
CAP_ARAVIS  Python: cv.CAP_ARAVIS	Aravis SDK.
CAP_OPENCV_MJPEG  Python: cv.CAP_OPENCV_MJPEG	Built-in OpenCV MotionJPEG codec.
CAP_INTEL_MFX  Python: cv.CAP_INTEL_MFX	Intel MediaSDK.
CAP_XINE  Python: cv.CAP_XINE	XINE engine (Linux)
CAP_UEYE  Python: cv.CAP_UEYE	uEye Camera API
CAP_OBSENSOR  Python: cv.CAP_OBSENSOR	For Orbbec 3D-Sensor device/module (Astra+, Femto)

VideoCaptureProperties

enum cv::VideoCaptureProperties

#include <opencv2/videoio.hpp>

cv::VideoCapture generic properties identifier.

Reading / writing properties involves many layers. Some unexpected result might happens along this chain. Effective behaviour depends from device hardware, driver and API Backend.

See also

Additional flags for video I/O API backends, VideoCapture::get(), VideoCapture::set()

Enumerator
CAP_PROP_POS_MSEC  Python: cv.CAP_PROP_POS_MSEC	Current position of the video file in milliseconds.
CAP_PROP_POS_FRAMES  Python: cv.CAP_PROP_POS_FRAMES	0-based index of the frame to be decoded/captured next.
CAP_PROP_POS_AVI_RATIO  Python: cv.CAP_PROP_POS_AVI_RATIO	Relative position of the video file: 0=start of the film, 1=end of the film.
CAP_PROP_FRAME_WIDTH  Python: cv.CAP_PROP_FRAME_WIDTH	Width of the frames in the video stream.
CAP_PROP_FRAME_HEIGHT  Python: cv.CAP_PROP_FRAME_HEIGHT	Height of the frames in the video stream.
CAP_PROP_FPS  Python: cv.CAP_PROP_FPS	Frame rate.
CAP_PROP_FOURCC  Python: cv.CAP_PROP_FOURCC	4-character code of codec. see VideoWriter::fourcc .
CAP_PROP_FRAME_COUNT  Python: cv.CAP_PROP_FRAME_COUNT	Number of frames in the video file.
CAP_PROP_FORMAT  Python: cv.CAP_PROP_FORMAT	Format of the Mat objects (see Mat::type()) returned by VideoCapture::retrieve(). Set value -1 to fetch undecoded RAW video streams (as Mat 8UC1).
CAP_PROP_MODE  Python: cv.CAP_PROP_MODE	Backend-specific value indicating the current capture mode.
CAP_PROP_BRIGHTNESS  Python: cv.CAP_PROP_BRIGHTNESS	Brightness of the image (only for those cameras that support).
CAP_PROP_CONTRAST  Python: cv.CAP_PROP_CONTRAST	Contrast of the image (only for cameras).
CAP_PROP_SATURATION  Python: cv.CAP_PROP_SATURATION	Saturation of the image (only for cameras).
CAP_PROP_HUE  Python: cv.CAP_PROP_HUE	Hue of the image (only for cameras).
CAP_PROP_GAIN  Python: cv.CAP_PROP_GAIN	Gain of the image (only for those cameras that support).
CAP_PROP_EXPOSURE  Python: cv.CAP_PROP_EXPOSURE	Exposure (only for those cameras that support).
CAP_PROP_CONVERT_RGB  Python: cv.CAP_PROP_CONVERT_RGB	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.
CAP_PROP_WHITE_BALANCE_BLUE_U  Python: cv.CAP_PROP_WHITE_BALANCE_BLUE_U	Currently unsupported.
CAP_PROP_RECTIFICATION  Python: cv.CAP_PROP_RECTIFICATION	Rectification flag for stereo cameras (note: only supported by DC1394 v 2.x backend currently).
CAP_PROP_MONOCHROME  Python: cv.CAP_PROP_MONOCHROME
CAP_PROP_SHARPNESS  Python: cv.CAP_PROP_SHARPNESS
CAP_PROP_AUTO_EXPOSURE  Python: cv.CAP_PROP_AUTO_EXPOSURE	DC1394: exposure control done by camera, user can adjust reference level using this feature.
CAP_PROP_GAMMA  Python: cv.CAP_PROP_GAMMA
CAP_PROP_TEMPERATURE  Python: cv.CAP_PROP_TEMPERATURE
CAP_PROP_TRIGGER  Python: cv.CAP_PROP_TRIGGER
CAP_PROP_TRIGGER_DELAY  Python: cv.CAP_PROP_TRIGGER_DELAY
CAP_PROP_WHITE_BALANCE_RED_V  Python: cv.CAP_PROP_WHITE_BALANCE_RED_V
CAP_PROP_ZOOM  Python: cv.CAP_PROP_ZOOM
CAP_PROP_FOCUS  Python: cv.CAP_PROP_FOCUS
CAP_PROP_GUID  Python: cv.CAP_PROP_GUID
CAP_PROP_ISO_SPEED  Python: cv.CAP_PROP_ISO_SPEED
CAP_PROP_BACKLIGHT  Python: cv.CAP_PROP_BACKLIGHT
CAP_PROP_PAN  Python: cv.CAP_PROP_PAN
CAP_PROP_TILT  Python: cv.CAP_PROP_TILT
CAP_PROP_ROLL  Python: cv.CAP_PROP_ROLL
CAP_PROP_IRIS  Python: cv.CAP_PROP_IRIS
CAP_PROP_SETTINGS  Python: cv.CAP_PROP_SETTINGS	Pop up video/camera filter dialog (note: only supported by DSHOW backend currently. The property value is ignored)
CAP_PROP_BUFFERSIZE  Python: cv.CAP_PROP_BUFFERSIZE
CAP_PROP_AUTOFOCUS  Python: cv.CAP_PROP_AUTOFOCUS
CAP_PROP_SAR_NUM  Python: cv.CAP_PROP_SAR_NUM	Sample aspect ratio: num/den (num)
CAP_PROP_SAR_DEN  Python: cv.CAP_PROP_SAR_DEN	Sample aspect ratio: num/den (den)
CAP_PROP_BACKEND  Python: cv.CAP_PROP_BACKEND	Current backend (enum VideoCaptureAPIs). Read-only property.
CAP_PROP_CHANNEL  Python: cv.CAP_PROP_CHANNEL	Video input or Channel Number (only for those cameras that support)
CAP_PROP_AUTO_WB  Python: cv.CAP_PROP_AUTO_WB	enable/ disable auto white-balance
CAP_PROP_WB_TEMPERATURE  Python: cv.CAP_PROP_WB_TEMPERATURE	white-balance color temperature
CAP_PROP_CODEC_PIXEL_FORMAT  Python: cv.CAP_PROP_CODEC_PIXEL_FORMAT	(read-only) codec's pixel format. 4-character code - see VideoWriter::fourcc . Subset of AV_PIX_FMT_* or -1 if unknown
CAP_PROP_BITRATE  Python: cv.CAP_PROP_BITRATE	(read-only) Video bitrate in kbits/s
CAP_PROP_ORIENTATION_META  Python: cv.CAP_PROP_ORIENTATION_META	(read-only) Frame rotation defined by stream meta (applicable for FFmpeg and AVFoundation back-ends only)
CAP_PROP_ORIENTATION_AUTO  Python: cv.CAP_PROP_ORIENTATION_AUTO	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)
CAP_PROP_HW_ACCELERATION  Python: cv.CAP_PROP_HW_ACCELERATION	(open-only) Hardware acceleration type (see VideoAccelerationType). Setting supported only via params parameter in cv::VideoCapture constructor / .open() method. Default value is backend-specific.
CAP_PROP_HW_DEVICE  Python: cv.CAP_PROP_HW_DEVICE	(open-only) Hardware device index (select GPU if multiple available). Device enumeration is acceleration type specific.
CAP_PROP_HW_ACCELERATION_USE_OPENCL  Python: cv.CAP_PROP_HW_ACCELERATION_USE_OPENCL	(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.
CAP_PROP_OPEN_TIMEOUT_MSEC  Python: cv.CAP_PROP_OPEN_TIMEOUT_MSEC	(open-only) timeout in milliseconds for opening a video capture (applicable for FFmpeg and GStreamer back-ends only)
CAP_PROP_READ_TIMEOUT_MSEC  Python: cv.CAP_PROP_READ_TIMEOUT_MSEC	(open-only) timeout in milliseconds for reading from a video capture (applicable for FFmpeg and GStreamer back-ends only)
CAP_PROP_STREAM_OPEN_TIME_USEC  Python: cv.CAP_PROP_STREAM_OPEN_TIME_USEC
CAP_PROP_VIDEO_TOTAL_CHANNELS  Python: cv.CAP_PROP_VIDEO_TOTAL_CHANNELS	(read-only) Number of video channels
CAP_PROP_VIDEO_STREAM  Python: cv.CAP_PROP_VIDEO_STREAM	(open-only) Specify video stream, 0-based index. Use -1 to disable video stream from file or IP cameras. Default value is 0.
CAP_PROP_AUDIO_STREAM  Python: cv.CAP_PROP_AUDIO_STREAM	(open-only) Specify stream in multi-language media files, -1 - disable audio processing or microphone. Default value is -1.
CAP_PROP_AUDIO_POS  Python: cv.CAP_PROP_AUDIO_POS	(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.
CAP_PROP_AUDIO_SHIFT_NSEC  Python: cv.CAP_PROP_AUDIO_SHIFT_NSEC	(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.
CAP_PROP_AUDIO_DATA_DEPTH  Python: cv.CAP_PROP_AUDIO_DATA_DEPTH	(open, read) Alternative definition to bits-per-sample, but with clear handling of 32F / 32S
CAP_PROP_AUDIO_SAMPLES_PER_SECOND  Python: cv.CAP_PROP_AUDIO_SAMPLES_PER_SECOND	(open, read) determined from file/codec input. If not specified, then selected audio sample rate is 44100
CAP_PROP_AUDIO_BASE_INDEX  Python: cv.CAP_PROP_AUDIO_BASE_INDEX	(read-only) Index of the first audio channel for .retrieve() calls. That audio channel number continues enumeration after video channels.
CAP_PROP_AUDIO_TOTAL_CHANNELS  Python: cv.CAP_PROP_AUDIO_TOTAL_CHANNELS	(read-only) Number of audio channels in the selected audio stream (mono, stereo, etc)
CAP_PROP_AUDIO_TOTAL_STREAMS  Python: cv.CAP_PROP_AUDIO_TOTAL_STREAMS	(read-only) Number of audio streams.
CAP_PROP_AUDIO_SYNCHRONIZE  Python: cv.CAP_PROP_AUDIO_SYNCHRONIZE	(open, read) Enables audio synchronization.
CAP_PROP_LRF_HAS_KEY_FRAME  Python: cv.CAP_PROP_LRF_HAS_KEY_FRAME	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.
CAP_PROP_CODEC_EXTRADATA_INDEX  Python: cv.CAP_PROP_CODEC_EXTRADATA_INDEX	Positive index indicates that returning extra data is supported by the video back end. This can be retrieved as cap.retrieve(data, <returned index>). 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, <returned index>).
CAP_PROP_FRAME_TYPE  Python: cv.CAP_PROP_FRAME_TYPE	(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.
CAP_PROP_N_THREADS  Python: cv.CAP_PROP_N_THREADS	(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).

VideoWriterProperties

enum cv::VideoWriterProperties

#include <opencv2/videoio.hpp>

cv::VideoWriter generic properties identifier.

See also

VideoWriter::get(), VideoWriter::set()

Enumerator
VIDEOWRITER_PROP_QUALITY  Python: cv.VIDEOWRITER_PROP_QUALITY	Current quality (0..100%) of the encoded videostream. Can be adjusted dynamically in some codecs.
VIDEOWRITER_PROP_FRAMEBYTES  Python: cv.VIDEOWRITER_PROP_FRAMEBYTES	(Read-only): Size of just encoded video frame. Note that the encoding order may be different from representation order.
VIDEOWRITER_PROP_NSTRIPES  Python: cv.VIDEOWRITER_PROP_NSTRIPES	Number of stripes for parallel encoding. -1 for auto detection.
VIDEOWRITER_PROP_IS_COLOR  Python: cv.VIDEOWRITER_PROP_IS_COLOR	If it is not zero, the encoder will expect and encode color frames, otherwise it will work with grayscale frames.
VIDEOWRITER_PROP_DEPTH  Python: cv.VIDEOWRITER_PROP_DEPTH	Defaults to CV_8U.
VIDEOWRITER_PROP_HW_ACCELERATION  Python: cv.VIDEOWRITER_PROP_HW_ACCELERATION	(open-only) Hardware acceleration type (see VideoAccelerationType). Setting supported only via params parameter in VideoWriter constructor / .open() method. Default value is backend-specific.
VIDEOWRITER_PROP_HW_DEVICE  Python: cv.VIDEOWRITER_PROP_HW_DEVICE	(open-only) Hardware device index (select GPU if multiple available). Device enumeration is acceleration type specific.
VIDEOWRITER_PROP_HW_ACCELERATION_USE_OPENCL  Python: cv.VIDEOWRITER_PROP_HW_ACCELERATION_USE_OPENCL	(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.