| // 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) 2020 Intel Corporation | |
| // Forward declaration | |
| namespace cv { | |
| namespace gapi { | |
| namespace s11n { | |
| struct IOStream; | |
| struct IIStream; | |
| } // namespace s11n | |
| } // namespace gapi | |
| } // namespace cv | |
| namespace cv { | |
| /** \addtogroup gapi_data_structures | |
| * @{ | |
| * | |
| * @brief Extra G-API data structures used to pass input/output data | |
| * to the graph for processing. | |
| */ | |
| /** | |
| * @brief cv::MediaFrame class represents an image/media frame | |
| * obtained from an external source. | |
| * | |
| * cv::MediaFrame represents image data as specified in | |
| * cv::MediaFormat. cv::MediaFrame is designed to be a thin wrapper over some | |
| * external memory of buffer; the class itself provides an uniform | |
| * interface over such types of memory. cv::MediaFrame wraps data from | |
| * a camera driver or from a media codec and provides an abstraction | |
| * layer over this memory to G-API. MediaFrame defines a compact interface | |
| * to access and manage the underlying data; the implementation is | |
| * fully defined by the associated Adapter (which is usually | |
| * user-defined). | |
| * | |
| * @sa cv::RMat | |
| */ | |
| class GAPI_EXPORTS MediaFrame { | |
| public: | |
| /// This enum defines different types of cv::MediaFrame provided | |
| /// access to the underlying data. Note that different flags can't | |
| /// be combined in this version. | |
| enum class Access { | |
| R, ///< Access data for reading | |
| W, ///< Access data for writing | |
| }; | |
| class IAdapter; | |
| class View; | |
| using AdapterPtr = std::unique_ptr<IAdapter>; | |
| /** | |
| * @brief Constructs an empty MediaFrame | |
| * | |
| * The constructed object has no any data associated with it. | |
| */ | |
| MediaFrame(); | |
| /** | |
| * @brief Constructs a MediaFrame with the given | |
| * Adapter. MediaFrame takes ownership over the passed adapter. | |
| * | |
| * @param p an unique pointer to instance of IAdapter derived class. | |
| */ | |
| explicit MediaFrame(AdapterPtr &&p); | |
| /** | |
| * @overload | |
| * @brief Constructs a MediaFrame with the given parameters for | |
| * the Adapter. The adapter of type `T` is costructed on the fly. | |
| * | |
| * @param args list of arguments to construct an adapter of type | |
| * `T`. | |
| */ | |
| template<class T, class... Args> static cv::MediaFrame Create(Args&&... args); | |
| /** | |
| * @brief Obtain access to the underlying data with the given | |
| * mode. | |
| * | |
| * Depending on the associated Adapter and the data wrapped, this | |
| * method may be cheap (e.g., the underlying memory is local) or | |
| * costly (if the underlying memory is external or device | |
| * memory). | |
| * | |
| * @param mode an access mode flag | |
| * @return a MediaFrame::View object. The views should be handled | |
| * carefully, refer to the MediaFrame::View documentation for details. | |
| */ | |
| View access(Access mode) const; | |
| /** | |
| * @brief Returns a media frame descriptor -- the information | |
| * about the media format, dimensions, etc. | |
| * @return a cv::GFrameDesc | |
| */ | |
| cv::GFrameDesc desc() const; | |
| // FIXME: design a better solution | |
| // Should be used only if the actual adapter provides implementation | |
| /// @private -- exclude from the OpenCV documentation for now. | |
| cv::util::any blobParams() const; | |
| /** | |
| * @brief Casts and returns the associated MediaFrame adapter to | |
| * the particular adapter type `T`, returns nullptr if the type is | |
| * different. | |
| * | |
| * This method may be useful if the adapter type is known by the | |
| * caller, and some lower level access to the memory is required. | |
| * Depending on the memory type, it may be more efficient than | |
| * access(). | |
| * | |
| * @return a pointer to the adapter object, nullptr if the adapter | |
| * type is different. | |
| */ | |
| template<typename T> T* get() const { | |
| static_assert(std::is_base_of<IAdapter, T>::value, | |
| "T is not derived from cv::MediaFrame::IAdapter!"); | |
| auto* adapter = getAdapter(); | |
| GAPI_Assert(adapter != nullptr); | |
| return dynamic_cast<T*>(adapter); | |
| } | |
| /** | |
| * @brief Serialize MediaFrame's data to a byte array. | |
| * | |
| * @note The actual logic is implemented by frame's adapter class. | |
| * Does nothing by default. | |
| * | |
| * @param os Bytestream to store serialized MediaFrame data in. | |
| */ | |
| void serialize(cv::gapi::s11n::IOStream& os) const; | |
| private: | |
| struct Priv; | |
| std::shared_ptr<Priv> m; | |
| IAdapter* getAdapter() const; | |
| }; | |
| template<class T, class... Args> | |
| inline cv::MediaFrame cv::MediaFrame::Create(Args&&... args) { | |
| std::unique_ptr<T> ptr(new T(std::forward<Args>(args)...)); | |
| return cv::MediaFrame(std::move(ptr)); | |
| } | |
| /** | |
| * @brief Provides access to the MediaFrame's underlying data. | |
| * | |
| * This object contains the necessary information to access the pixel | |
| * data of the associated MediaFrame: arrays of pointers and strides | |
| * (distance between every plane row, in bytes) for every image | |
| * plane, as defined in cv::MediaFormat. | |
| * There may be up to four image planes in MediaFrame. | |
| * | |
| * Depending on the MediaFrame::Access flag passed in | |
| * MediaFrame::access(), a MediaFrame::View may be read- or | |
| * write-only. | |
| * | |
| * Depending on the MediaFrame::IAdapter implementation associated | |
| * with the parent MediaFrame, writing to memory with | |
| * MediaFrame::Access::R flag may have no effect or lead to | |
| * undefined behavior. Same applies to reading the memory with | |
| * MediaFrame::Access::W flag -- again, depending on the IAdapter | |
| * implementation, the host-side buffer the view provides access to | |
| * may have no current data stored in (so in-place editing of the | |
| * buffer contents may not be possible). | |
| * | |
| * MediaFrame::View objects must be handled carefully, as an external | |
| * resource associated with MediaFrame may be locked for the time the | |
| * MediaFrame::View object exists. Obtaining MediaFrame::View should | |
| * be seen as "map" and destroying it as "unmap" in the "map/unmap" | |
| * idiom (applicable to OpenCL, device memory, remote | |
| * memory). | |
| * | |
| * When a MediaFrame buffer is accessed for writing, and the memory | |
| * under MediaFrame::View::Ptrs is altered, the data synchronization | |
| * of a host-side and device/remote buffer is not guaranteed until the | |
| * MediaFrame::View is destroyed. In other words, the real data on the | |
| * device or in a remote target may be updated at the MediaFrame::View | |
| * destruction only -- but it depends on the associated | |
| * MediaFrame::IAdapter implementation. | |
| */ | |
| class GAPI_EXPORTS MediaFrame::View final { | |
| public: | |
| static constexpr const size_t MAX_PLANES = 4; | |
| using Ptrs = std::array<void*, MAX_PLANES>; | |
| using Strides = std::array<std::size_t, MAX_PLANES>; // in bytes | |
| using Callback = std::function<void()>; | |
| /// @private | |
| View(Ptrs&& ptrs, Strides&& strs, Callback &&cb = [](){}); | |
| /// @private | |
| View(const View&) = delete; | |
| /// @private | |
| View(View&&) = default; | |
| /// @private | |
| View& operator = (const View&) = delete; | |
| ~View(); | |
| Ptrs ptr; ///< Array of image plane pointers | |
| Strides stride; ///< Array of image plane strides, in bytes. | |
| private: | |
| Callback m_cb; | |
| }; | |
| /** | |
| * @brief An interface class for MediaFrame data adapters. | |
| * | |
| * Implement this interface to wrap media data in the MediaFrame. It | |
| * makes sense to implement this class if there is a custom | |
| * cv::gapi::wip::IStreamSource defined -- in this case, a stream | |
| * source can produce MediaFrame objects with this adapter and the | |
| * media data may be passed to graph without any copy. For example, a | |
| * GStreamer-based stream source can implement an adapter over | |
| * `GstBuffer` and G-API will transparently use it in the graph. | |
| */ | |
| class GAPI_EXPORTS MediaFrame::IAdapter { | |
| public: | |
| virtual ~IAdapter() = 0; | |
| virtual cv::GFrameDesc meta() const = 0; | |
| virtual MediaFrame::View access(MediaFrame::Access) = 0; | |
| // FIXME: design a better solution | |
| // The default implementation does nothing | |
| virtual cv::util::any blobParams() const; | |
| virtual void serialize(cv::gapi::s11n::IOStream&) { | |
| GAPI_Error("Generic serialize method of MediaFrame::IAdapter does nothing by default. " | |
| "Please, implement it in derived class to properly serialize the object."); | |
| } | |
| virtual void deserialize(cv::gapi::s11n::IIStream&) { | |
| GAPI_Error("Generic deserialize method of MediaFrame::IAdapter does nothing by default. " | |
| "Please, implement it in derived class to properly deserialize the object."); | |
| } | |
| }; | |
| /** @} */ | |
| } //namespace cv | |