Video reader interface. More...

#include <opencv2/cudacodec.hpp>

Public Member Functions
virtual	~VideoReader ()

virtual FormatInfo	format () const =0
	Returns information about video file format.

virtual bool	get (const int propertyId, double &propertyVal) const =0
	Retrieves the specified property used by the VideoSource.

virtual bool	get (const VideoReaderProps propertyId, double &propertyVal) const =0
	Returns the specified VideoReader property.

virtual bool	getVideoReaderProps (const VideoReaderProps propertyId, double &propertyValOut, double propertyValIn=0) const =0

virtual bool	grab (cuda::Stream &stream=cuda::Stream::Null())=0
	Grabs the next frame from the video source.

virtual bool	nextFrame (cuda::GpuMat &frame, cuda::GpuMat &histogram, cuda::Stream &stream=cuda::Stream::Null())=0
	Grabs, decodes and returns the next video frame and frame luma histogram.

virtual bool	nextFrame (cuda::GpuMat &frame, cuda::Stream &stream=cuda::Stream::Null())=0
	Grabs, decodes and returns the next video frame.

bool	retrieve (cuda::GpuMat &frame) const
	Returns the next video frame.

bool	retrieve (Mat &frame, const size_t idx) const
	Returns previously grabbed encoded video data.

virtual bool	retrieve (OutputArray frame, const size_t idx=static_cast< size_t >(VideoReaderProps::PROP_DECODED_FRAME_IDX)) const =0
	Returns previously grabbed video data.

virtual bool	set (const ColorFormat colorFormat)=0
	Set the desired ColorFormat for the frame returned by nextFrame()/retrieve().

virtual bool	set (const VideoReaderProps propertyId, const double propertyVal)=0
	Sets a property in the VideoReader.

bool	setVideoReaderProps (const VideoReaderProps propertyId, double propertyVal)

Detailed Description

Video reader interface.

Available when built with WITH_NVCUVID=ON while Nvidia's Video Codec SDK is installed.

Decoding support is dependent on the GPU, refer to the Nvidia Video Codec SDK Video Encode and Decode GPU Support Matrix for details.

Note

An example on how to use the videoReader class can be found at opencv_source_code/samples/gpu/video_reader.cpp

Constructor & Destructor Documentation

◆ ~VideoReader()

virtual cv::cudacodec::VideoReader::~VideoReader ( )

inlinevirtual

Member Function Documentation

◆ format()

virtual FormatInfo cv::cudacodec::VideoReader::format ( ) const

pure virtual

Returns information about video file format.

◆ get() [1/2]

virtual bool cv::cudacodec::VideoReader::get	(	const int	propertyId,
		double &	propertyVal
	)		const

pure virtual

Retrieves the specified property used by the VideoSource.

Parameters

propertyId	Property identifier from cv::VideoCaptureProperties (eg. cv::CAP_PROP_POS_MSEC, cv::CAP_PROP_POS_FRAMES, ...) or one from Additional flags for video I/O API backends.
propertyVal	Value for the specified property.

Returns: true unless the property is unset set or not supported.

◆ get() [2/2]

virtual bool cv::cudacodec::VideoReader::get	(	const VideoReaderProps	propertyId,
		double &	propertyVal
	)		const

pure virtual

Returns the specified VideoReader property.

Parameters

propertyId	Property identifier from cv::cudacodec::VideoReaderProps (eg. cv::cudacodec::VideoReaderProps::PROP_DECODED_FRAME_IDX, cv::cudacodec::VideoReaderProps::PROP_EXTRA_DATA_INDEX, ...).
propertyVal	In: Optional value required for querying specific propertyId's, e.g. the index of the raw package to be checked for a key frame (cv::cudacodec::VideoReaderProps::PROP_LRF_HAS_KEY_FRAME). Out: Value of the property.

Returns: true unless the property is not supported.

◆ getVideoReaderProps()

virtual bool cv::cudacodec::VideoReader::getVideoReaderProps	(	const VideoReaderProps	propertyId,
		double &	propertyValOut,
		double	propertyValIn = `0`
	)		const

pure virtual

◆ grab()

virtual bool cv::cudacodec::VideoReader::grab ( cuda::Stream & stream = cuda::Stream::Null() )

pure virtual

Grabs the next frame from the video source.

Parameters

stream Stream for the asynchronous version.

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 for reading both the encoded and decoded video data when rawMode is enabled. With rawMode enabled retrieve() can be called following grab() to retrieve all the data associated with the current video source since the last call to grab() or the creation of the VideoReader.

◆ nextFrame() [1/2]

virtual bool cv::cudacodec::VideoReader::nextFrame	(	cuda::GpuMat &	frame,
		cuda::GpuMat &	histogram,
		cuda::Stream &	stream = `cuda::Stream::Null()`
	)

pure virtual

Grabs, decodes and returns the next video frame and frame luma histogram.

Parameters

[out]	frame	The video frame.
[out]	histogram	Histogram of the luma component of the encoded frame, see note.
	stream	Stream for the asynchronous version.

Returns: false if no frames have been grabbed.

If no frames have been grabbed (there are no more frames in video file), the methods return false. The method throws an Exception if error occurs.

Note: Histogram data is collected by NVDEC during the decoding process resulting in zero performance penalty. NVDEC computes the histogram data for only the luma component of decoded output, not on post-processed frame(i.e. when scaling, cropping, etc. applied). If the source is encoded using a limited range of luma values (FormatInfo::videoFullRangeFlag == false) then the histogram bin values will correspond to to this limited range of values and will need to be mapped to contain the same output as cuda::calcHist(). The MapHist() utility function can be used to perform this mapping on the host if required.

◆ nextFrame() [2/2]

virtual bool cv::cudacodec::VideoReader::nextFrame	(	cuda::GpuMat &	frame,
		cuda::Stream &	stream = `cuda::Stream::Null()`
	)

pure virtual

Grabs, decodes and returns the next video frame.

Parameters

[out]	frame	The video frame.
	stream	Stream for the asynchronous version.

Returns: false if no frames have been grabbed.

If no frames have been grabbed (there are no more frames in video file), the methods return false. The method throws an Exception if error occurs.

◆ retrieve() [1/3]

bool cv::cudacodec::VideoReader::retrieve ( cuda::GpuMat & frame ) const

inline

Returns the next video frame.

Parameters

[out] frame The video frame. If grab() has not been called then this will be empty().

Returns: false if no frames have been grabbed

The method returns data associated with the current video source since the last call to grab(). If no data is present the method returns false and the function returns an empty image.

◆ retrieve() [2/3]

bool cv::cudacodec::VideoReader::retrieve	(	Mat &	frame,
		const size_t	idx
	)		const

inline

Returns previously grabbed encoded video data.

Parameters

[out]	frame	The encoded video data.
	idx	Determines the returned data inside image. The returned data can be the: Extra data if available, idx = get(PROP_EXTRA_DATA_INDEX). Raw encoded data package. To retrieve package i, idx = get(PROP_RAW_PACKAGES_BASE_INDEX) + i with i < get(PROP_NUMBER_OF_RAW_PACKAGES_SINCE_LAST_GRAB)

Returns: false if no frames have been grabbed

The method returns data associated with the current video source since the last call to grab() or the creation of the VideoReader. If no data is present the method returns false and the function returns an empty image.

◆ retrieve() [3/3]

virtual bool cv::cudacodec::VideoReader::retrieve	(	OutputArray	frame,
		const size_t	idx = `static_cast< size_t >(VideoReaderProps::PROP_DECODED_FRAME_IDX)`
	)		const

pure virtual

Returns previously grabbed video data.

Parameters

[out]	frame	The returned data which depends on the provided idx.
	idx	Determines the returned data inside image. The returned data can be the: Decoded frame, idx = get(PROP_DECODED_FRAME_IDX). Extra data if available, idx = get(PROP_EXTRA_DATA_INDEX). Raw encoded data package. To retrieve package i, idx = get(PROP_RAW_PACKAGES_BASE_INDEX) + i with i < get(PROP_NUMBER_OF_RAW_PACKAGES_SINCE_LAST_GRAB)

Returns: false if no frames have been grabbed

The method returns data associated with the current video source since the last call to grab() or the creation of the VideoReader. If no data is present the method returns false and the function returns an empty image.

◆ set() [1/2]

virtual bool cv::cudacodec::VideoReader::set ( const ColorFormat colorFormat )

pure virtual

Set the desired ColorFormat for the frame returned by nextFrame()/retrieve().

Parameters

colorFormat Value of the ColorFormat.

Returns: true unless the colorFormat is not supported.

◆ set() [2/2]

virtual bool cv::cudacodec::VideoReader::set	(	const VideoReaderProps	propertyId,
		const double	propertyVal
	)

pure virtual

Sets a property in the VideoReader.

Parameters

propertyId	Property identifier from cv::cudacodec::VideoReaderProps (eg. cv::cudacodec::VideoReaderProps::PROP_DECODED_FRAME_IDX, cv::cudacodec::VideoReaderProps::PROP_EXTRA_DATA_INDEX, ...).
propertyVal	Value of the property.

Returns: true if the property has been set.

◆ setVideoReaderProps()

bool cv::cudacodec::VideoReader::setVideoReaderProps	(	const VideoReaderProps	propertyId,
		double	propertyVal
	)

inline

The documentation for this class was generated from the following file:

opencv2/cudacodec.hpp

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ ~VideoReader()

Member Function Documentation

◆ format()

◆ get() [1/2]

◆ get() [2/2]

◆ getVideoReaderProps()

◆ grab()

◆ nextFrame() [1/2]

◆ nextFrame() [2/2]

◆ retrieve() [1/3]

◆ retrieve() [2/3]

◆ retrieve() [3/3]

◆ set() [1/2]

◆ set() [2/2]

◆ setVideoReaderProps()