Try to use GPU video decoding plugins when possible

GstToolkit.cpp

@@ -2,6 +2,8 @@
 #include <iomanip>
 using namespace std;
 
+#include <gst/gl/gl.h>
+
 #include "GstToolkit.h"
 
 string GstToolkit::time_to_string(guint64 t, time_string_mode m)
@@ -121,3 +123,37 @@ string GstToolkit::gst_version()
 
     return oss.str();
 }
+
+
+// see https://developer.ridgerun.com/wiki/index.php?title=GStreamer_modify_the_elements_rank
+
+std::list<std::string> GstToolkit::enable_gpu_decoding_plugins()
+{
+    static list<string> pluginslist;
+    static GstRegistry* plugins_register = nullptr;
+
+    if ( plugins_register == nullptr ) {
+        plugins_register = gst_registry_get();
+
+#if GST_GL_HAVE_PLATFORM_GLX
+        // https://gstreamer.freedesktop.org/documentation/nvcodec/index.html?gi-language=c#plugin-nvcodec
+        const char *plugins[6] = { "nvh264dec", "nvh265dec", "nvmpeg2videodec",
+                                   "nvmpeg4videodec", "nvvp8dec", "nvvp9dec" };
+        const int N = 6;
+#elif GST_GL_HAVE_PLATFORM_WGL
+        const char *plugins[1] = { "avdec_h264"};
+        const int N = 1;
+#endif
+
+        for (int i = 0; i < N; i++) {
+            GstPluginFeature* feature = gst_registry_lookup_feature(plugins_register, plugins[i]);
+            if(feature != NULL) {
+                pluginslist.push_front( string( plugins[i] ) );
+                gst_plugin_feature_set_rank(feature, GST_RANK_PRIMARY + 1);
+                gst_object_unref(feature);
+            }
+        }
+    }
+
+    return pluginslist;
+}

GstToolkit.h

@@ -18,9 +18,11 @@ typedef enum {
 std::string time_to_string(guint64 t, time_string_mode m = TIME_STRING_ADJUSTED);
 
 std::string gst_version();
-std::list<std::string> all_plugins();
-std::list<std::string> all_plugin_features(std::string pluginname);
 
+std::list<std::string> all_plugins();
+std::list<std::string> enable_gpu_decoding_plugins();
+
+std::list<std::string> all_plugin_features(std::string pluginname);
 bool enable_feature (std::string name, bool enable);
 
 }

RenderingManager.cpp

@@ -157,6 +157,15 @@ bool Rendering::init()
     g_setenv ("GST_GL_API", "opengl3", TRUE);
     gst_init (NULL, NULL);
 
+    // increase selection rank for GPU decoding plugins
+    if (Settings::application.render.gpu_decoding) {
+        std::list<std::string> gpuplugins = GstToolkit::enable_gpu_decoding_plugins();
+        if (gpuplugins.size() > 0) {
+            Log::Info("Video decoding favoring the following GPU decoding plugin(s):");
+            for(auto it = gpuplugins.begin(); it != gpuplugins.end(); it++)
+                Log::Info(" - %s", (*it).c_str());
+        }
+    }
 
 //#if GST_GL_HAVE_PLATFORM_WGL
 //    global_gl_context = gst_gl_context_new_wrapped (display, (guintptr) wglGetCurrentContext (),

Settings.cpp

@@ -82,6 +82,7 @@ void Settings::Save()
     RenderNode->SetAttribute("vsync", application.render.vsync);
     RenderNode->SetAttribute("multisampling", application.render.multisampling);
     RenderNode->SetAttribute("blit", application.render.blit);
+    RenderNode->SetAttribute("gpu_decoding", application.render.gpu_decoding);
     RenderNode->SetAttribute("ratio", application.render.ratio);
     RenderNode->SetAttribute("res", application.render.res);
     pRoot->InsertEndChild(RenderNode);
@@ -264,6 +265,7 @@ void Settings::Load()
         rendernode->QueryIntAttribute("vsync", &application.render.vsync);
         rendernode->QueryIntAttribute("multisampling", &application.render.multisampling);
         rendernode->QueryBoolAttribute("blit", &application.render.blit);
+        rendernode->QueryBoolAttribute("gpu_decoding", &application.render.gpu_decoding);
         rendernode->QueryIntAttribute("ratio", &application.render.ratio);
         rendernode->QueryIntAttribute("res", &application.render.res);
     }

Settings.h

@@ -136,14 +136,16 @@ struct RenderConfig
     int ratio;
     int res;
     float fading;
+    bool gpu_decoding;
 
     RenderConfig() {
         blit = false;
-        vsync = 1; // todo GUI selection
+        vsync = 1;
-        multisampling = 2; // todo GUI selection
+        multisampling = 2;
         ratio = 3;
         res = 1;
         fading = 0.0;
+        gpu_decoding = true;
     }
 };
 

UserInterfaceManager.cpp

@@ -2886,7 +2886,11 @@ void ShowConfig(bool* p_open)
         bool vsync = (Settings::application.render.vsync < 2);
         ImGui::Checkbox("Sync refresh with monitor (v-sync 60Hz)", &vsync);
         Settings::application.render.vsync = vsync ? 1 : 2;
+        ImGui::Checkbox("Use GPU video decoding when possible", &Settings::application.render.gpu_decoding);
+        ImGui::Spacing();
         ImGui::Text( ICON_FA_EXCLAMATION "  Restart the application for change to take effect.");
+        if (ImGui::Button( ICON_FA_POWER_OFF "  Quit  ", ImVec2(250,0)))
+            Rendering::manager().close();
     }
 
     ImGui::End();