decklink: Add Blackmagic DeckLink capture plugin

This is a cross-platform Blackmagic device capture plugin that makes use
of the manufacturer provided DeckLink SDK.

plugins/decklink/decklink-device-mode.cpp

@@ -0,0 +1,43 @@
+#include "decklink-device-mode.hpp"
+
+DeckLinkDeviceMode::DeckLinkDeviceMode(IDeckLinkDisplayMode *mode,
+		long long id) : id(id), mode(mode)
+{
+	if (mode == nullptr)
+		return;
+
+	mode->AddRef();
+
+	decklink_string_t decklinkStringName;
+	if (mode->GetName(&decklinkStringName) == S_OK)
+		DeckLinkStringToStdString(decklinkStringName, name);
+}
+
+DeckLinkDeviceMode::DeckLinkDeviceMode(const std::string& name, long long id) :
+	id(id), mode(nullptr), name(name)
+{
+}
+
+DeckLinkDeviceMode::~DeckLinkDeviceMode(void)
+{
+	if (mode != nullptr)
+		mode->Release();
+}
+
+BMDDisplayMode DeckLinkDeviceMode::GetDisplayMode(void) const
+{
+	if (mode != nullptr)
+		return mode->GetDisplayMode();
+
+	return bmdModeUnknown;
+}
+
+long long DeckLinkDeviceMode::GetId(void) const
+{
+	return id;
+}
+
+const std::string& DeckLinkDeviceMode::GetName(void) const
+{
+	return name;
+}