image_framework_ymj/include/opencv4.2/opencv2/gapi/gstreaming.hpp

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// This file is part of OpenCV project.
// It is subject to the license terms in the LICENSE file found in the top-level directory
// of this distribution and at http://opencv.org/license.html.
//
// Copyright (C) 2018 Intel Corporation
#ifndef OPENCV_GAPI_GSTREAMING_COMPILED_HPP
#define OPENCV_GAPI_GSTREAMING_COMPILED_HPP
#include <vector>
#include <opencv2/gapi/opencv_includes.hpp>
#include <opencv2/gapi/own/assert.hpp>
#include <opencv2/gapi/garg.hpp>
#include <opencv2/gapi/streaming/source.hpp>
namespace cv {
/**
* \addtogroup gapi_main_classes
* @{
*/
/**
* @brief Represents a computation (graph) compiled for streaming.
*
* This class represents a product of graph compilation (calling
* cv::GComputation::compileStreaming()). Objects of this class
* actually do stream processing, and the whole pipeline execution
* complexity is incapsulated into objects of this class. Execution
* model has two levels: at the very top, the execution of a
* heterogeneous graph is aggressively pipelined; at the very bottom
* the execution of every internal block is determined by its
* associated backend. Backends are selected based on kernel packages
* passed via compilation arguments ( see @ref gapi_compile_args,
* GNetworkPackage, GKernelPackage for details).
*
* GStreamingCompiled objects have a "player" semantics -- there are
* methods like start() and stop(). GStreamingCompiled has a full
* control over a videostream and so is stateful. You need to specify the
* input stream data using setSource() and then call start() to
* actually start processing. After that, use pull() or try_pull() to
* obtain next processed data frame from the graph in a blocking or
* non-blocking way, respectively.
*
* Currently a single GStreamingCompiled can process only one video
* streat at time. Produce multiple GStreamingCompiled objects to run the
* same graph on multiple video streams.
*
* @sa GCompiled
*/
class GAPI_EXPORTS GStreamingCompiled
{
public:
class GAPI_EXPORTS Priv;
GStreamingCompiled();
// FIXME: More overloads?
/**
* @brief Specify the input data to GStreamingCompiled for
* processing, a generic version.
*
* Use gin() to create an input parameter vector.
*
* Input vectors must have the same number of elements as defined
* in the cv::GComputation protocol (at the moment of its
* construction). Shapes of elements also must conform to protocol
* (e.g. cv::Mat needs to be passed where cv::GMat has been
* declared as input, and so on). Run-time exception is generated
* on type mismatch.
*
* In contrast with regular GCompiled, user can also pass an
* object of type GVideoCapture for a GMat parameter of the parent
* GComputation. The compiled pipeline will start fetching data
* from that GVideoCapture and feeding it into the
* pipeline. Pipeline stops when a GVideoCapture marks end of the
* stream (or when stop() is called).
*
* Passing a regular Mat for a GMat parameter makes it "infinite"
* source -- pipeline may run forever feeding with this Mat until
* stopped explicitly.
*
* Currently only a single GVideoCapture is supported as input. If
* the parent GComputation is declared with multiple input GMat's,
* one of those can be specified as GVideoCapture but all others
* must be regular Mat objects.
*
* Throws if pipeline is already running. Use stop() and then
* setSource() to run the graph on a new video stream.
*
* @note This method is not thread-safe (with respect to the user
* side) at the moment. Protect the access if
* start()/stop()/setSource() may be called on the same object in
* multiple threads in your application.
*
* @param ins vector of inputs to process.
* @sa gin
*/
void setSource(GRunArgs &&ins);
/**
* @brief Specify an input video stream for a single-input
* computation pipeline.
*
* Throws if pipeline is already running. Use stop() and then
* setSource() to run the graph on a new video stream.
*
* @overload
* @param s a shared pointer to IStreamSource representing the
* input video stream.
*/
void setSource(const gapi::wip::IStreamSource::Ptr& s);
/**
* @brief Start the pipeline execution.
*
* Use pull()/try_pull() to obtain data. Throws an exception if
* a video source was not specified.
*
* setSource() must be called first, even if the pipeline has been
* working already and then stopped (explicitly via stop() or due
* stream completion)
*
* @note This method is not thread-safe (with respect to the user
* side) at the moment. Protect the access if
* start()/stop()/setSource() may be called on the same object in
* multiple threads in your application.
*/
void start();
/**
* @brief Get the next processed frame from the pipeline.
*
* Use gout() to create an output parameter vector.
*
* Output vectors must have the same number of elements as defined
* in the cv::GComputation protocol (at the moment of its
* construction). Shapes of elements also must conform to protocol
* (e.g. cv::Mat needs to be passed where cv::GMat has been
* declared as output, and so on). Run-time exception is generated
* on type mismatch.
*
* This method writes new data into objects passed via output
* vector. If there is no data ready yet, this method blocks. Use
* try_pull() if you need a non-blocking version.
*
* @param outs vector of output parameters to obtain.
* @return true if next result has been obtained,
* false marks end of the stream.
*/
bool pull(cv::GRunArgsP &&outs);
/**
* @brief Try to get the next processed frame from the pipeline.
*
* Use gout() to create an output parameter vector.
*
* This method writes new data into objects passed via output
* vector. If there is no data ready yet, the output vector
* remains unchanged and false is returned.
*
* @return true if data has been obtained, and false if it was
* not. Note: false here doesn't mark the end of the stream.
*/
bool try_pull(cv::GRunArgsP &&outs);
/**
* @brief Stop (abort) processing the pipeline.
*
* Note - it is not pause but a complete stop. Calling start()
* will cause G-API to start processing the stream from the early beginning.
*
* Throws if the pipeline is not running.
*/
void stop();
/**
* @brief Test if the pipeline is running.
*
* @note This method is not thread-safe (with respect to the user
* side) at the moment. Protect the access if
* start()/stop()/setSource() may be called on the same object in
* multiple threads in your application.
*
* @return true if the current stream is not over yet.
*/
bool running() const;
/// @private
Priv& priv();
/**
* @brief Check if compiled object is valid (non-empty)
*
* @return true if the object is runnable (valid), false otherwise
*/
explicit operator bool () const;
/**
* @brief Vector of metadata this graph was compiled for.
*
* @return Unless _reshape_ is not supported, return value is the
* same vector which was passed to cv::GComputation::compile() to
* produce this compiled object. Otherwise, it is the latest
* metadata vector passed to reshape() (if that call was
* successful).
*/
const GMetaArgs& metas() const; // Meta passed to compile()
/**
* @brief Vector of metadata descriptions of graph outputs
*
* @return vector with formats/resolutions of graph's output
* objects, auto-inferred from input metadata vector by
* operations which form this computation.
*
* @note GCompiled objects produced from the same
* cv::GComputiation graph with different input metas may return
* different values in this vector.
*/
const GMetaArgs& outMetas() const;
protected:
/// @private
std::shared_ptr<Priv> m_priv;
};
/** @} */
}
#endif // OPENCV_GAPI_GSTREAMING_COMPILED_HPP