Merge pull request #19009 from TolyaTalamanov:at/media-frame-copy

[G-API] GStreamingBackend

* Snapshot

* Implement StreamingBackend

* Refactoring

* Refactoring 2

* Clean up

* Add missing functionality to support MediaFrame as output

* Partially address review comments

* Fix build

* Implement reshape for gstreamingbackend and add a test on it

* Address more comments

* Add format.hpp to gapi.hpp

* Fix debug build

* Address review comments

Co-authored-by: Smirnov Alexey <alexey.smirnov@intel.com>

modules/gapi/include/opencv2/gapi.hpp

@@ -33,8 +33,9 @@
 #include <opencv2/gapi/gkernel.hpp>
 #include <opencv2/gapi/operators.hpp>
 
-// Include this file here to avoid cyclic dependency between
+// Include these files here to avoid cyclic dependency between
 // Desync & GKernel & GComputation & GStreamingCompiled.
 #include <opencv2/gapi/streaming/desync.hpp>
+#include <opencv2/gapi/streaming/format.hpp>
 
 #endif // OPENCV_GAPI_HPP

modules/gapi/include/opencv2/gapi/cpu/gcpukernel.hpp

@@ -101,6 +101,7 @@ public:
 
     const cv::Scalar& inVal(int input);
     cv::Scalar& outValR(int output); // FIXME: Avoid cv::Scalar s = ctx.outValR()
+    cv::MediaFrame& outFrame(int output);
     template<typename T> std::vector<T>& outVecR(int output) // FIXME: the same issue
     {
         return outVecRef(output).wref<T>();
@@ -258,6 +259,13 @@ template<> struct get_out<cv::GScalar>
         return ctx.outValR(idx);
     }
 };
+template<> struct get_out<cv::GFrame>
+{
+    static cv::MediaFrame& get(GCPUContext &ctx, int idx)
+    {
+        return ctx.outFrame(idx);
+    }
+};
 template<typename U> struct get_out<cv::GArray<U>>
 {
     static std::vector<U>& get(GCPUContext &ctx, int idx)

modules/gapi/include/opencv2/gapi/garg.hpp

@@ -210,6 +210,7 @@ using GRunArgP = util::variant<
     cv::Mat*,
     cv::RMat*,
     cv::Scalar*,
+    cv::MediaFrame*,
     cv::detail::VectorRef,
     cv::detail::OpaqueRef
     >;

modules/gapi/include/opencv2/gapi/gcall.hpp

@@ -11,6 +11,7 @@
 #include <opencv2/gapi/garg.hpp>      // GArg
 #include <opencv2/gapi/gmat.hpp>      // GMat
 #include <opencv2/gapi/gscalar.hpp>   // GScalar
+#include <opencv2/gapi/gframe.hpp>    // GFrame
 #include <opencv2/gapi/garray.hpp>    // GArray<T>
 #include <opencv2/gapi/gopaque.hpp>   // GOpaque<T>
 
@@ -41,6 +42,7 @@ public:
     GMat    yield      (int output = 0);
     GMatP   yieldP     (int output = 0);
     GScalar yieldScalar(int output = 0);
+    GFrame  yieldFrame (int output = 0);
 
     template<class T> GArray<T> yieldArray(int output = 0)
     {

modules/gapi/include/opencv2/gapi/gframe.hpp

@@ -62,6 +62,9 @@ struct GAPI_EXPORTS GFrameDesc
 static inline GFrameDesc empty_gframe_desc() { return GFrameDesc{}; }
 /** @} */
 
+class MediaFrame;
+GAPI_EXPORTS GFrameDesc descr_of(const MediaFrame &frame);
+
 GAPI_EXPORTS std::ostream& operator<<(std::ostream& os, const cv::GFrameDesc &desc);
 
 } // namespace cv

modules/gapi/include/opencv2/gapi/gkernel.hpp

@@ -90,6 +90,10 @@ namespace detail
     {
         static inline cv::GOpaque<U> yield(cv::GCall &call, int i) { return call.yieldOpaque<U>(i); }
     };
+    template<> struct Yield<GFrame>
+    {
+        static inline cv::GFrame yield(cv::GCall &call, int i) { return call.yieldFrame(i); }
+    };
 
     ////////////////////////////////////////////////////////////////////////////
     // Helper classes which brings outputMeta() marshalling to kernel
@@ -239,8 +243,6 @@ public:
     using InArgs  = std::tuple<Args...>;
     using OutArgs = std::tuple<R>;
 
-    static_assert(!cv::detail::contains<GFrame, OutArgs>::value, "Values of GFrame type can't be used as operation outputs");
-
     static R on(Args... args)
     {
         cv::GCall call(GKernel{ K::id()

modules/gapi/include/opencv2/gapi/streaming/format.hpp

@@ -0,0 +1,52 @@
+// 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
+
+#ifndef OPENCV_GAPI_GSTREAMING_FORMAT_HPP
+#define OPENCV_GAPI_GSTREAMING_FORMAT_HPP
+
+#include <opencv2/gapi/gkernel.hpp> // GKernelPackage
+
+namespace cv {
+namespace gapi {
+namespace streaming {
+
+cv::gapi::GKernelPackage kernels();
+cv::gapi::GBackend backend();
+
+// FIXME: Make a generic kernel
+G_API_OP(GCopy, <GFrame(GFrame)>, "org.opencv.streaming.copy")
+{
+    static GFrameDesc outMeta(const GFrameDesc& in) { return in; }
+};
+
+G_API_OP(GBGR, <GMat(GFrame)>, "org.opencv.streaming.BGR")
+{
+    static GMatDesc outMeta(const GFrameDesc& in) { return GMatDesc{CV_8U, 3, in.size}; }
+};
+
+/** @brief Gets copy from the input frame
+
+@note Function textual ID is "org.opencv.streaming.copy"
+
+@param in Input frame
+@return Copy of the input frame
+*/
+GAPI_EXPORTS cv::GFrame copy(const cv::GFrame& in);
+
+/** @brief Gets bgr plane from input frame
+
+@note Function textual ID is "org.opencv.streaming.BGR"
+
+@param in Input frame
+@return Image in BGR format
+*/
+GAPI_EXPORTS cv::GMat BGR (const cv::GFrame& in);
+
+} // namespace streaming
+} // namespace gapi
+} // namespace cv
+
+#endif // OPENCV_GAPI_GSTREAMING_FORMAT_HPP