// Copyright Epic Games, Inc. All Rights Reserved.

#include "GameplayMediaEncoder.h"
#include "Engine/GameEngine.h"
#include "HAL/IConsoleManager.h"
#include "Framework/Application/SlateApplication.h"
#include "Modules/ModuleManager.h"
#include "RendererInterface.h"
#include "ScreenRendering.h"
#include "ShaderCore.h"
#include "PipelineStateCache.h"
#include "ProfilingDebugging/CsvProfiler.h"
#include "IbmLiveStreaming.h"

#include "VideoEncoderFactory.h"
#include "VideoEncoderInput.h"

#include "ClearQuad.h"
#include "CommonRenderResources.h"

#include "AudioEncoderFactory.h"

DEFINE_LOG_CATEGORY(GameplayMediaEncoder);
CSV_DEFINE_CATEGORY(GameplayMediaEncoder, true);

// right now we support only 48KHz audio sample rate as it's the only config UE seems to output
// WMF AAC encoder supports also 44100Hz so its support can be easily added
const uint32 HardcodedAudioSamplerate = 48000;
// for now we downsample to stereo. WMF AAC encoder also supports 6 (5.1) channels
// so it can be added too
const uint32 HardcodedAudioNumChannels = 2;
// currently neither IVideoRecordingSystem neither HighlightFeature APIs allow to configure
// audio stream parameters
const uint32 HardcodedAudioBitrate = 192000;

// currently neither IVideoRecordingSystem neither HighlightFeature APIs allow to configure
// video stream parameters
#if PLATFORM_WINDOWS
const uint32 HardcodedVideoFPS = 60;
#else
const uint32 HardcodedVideoFPS = 30;
#endif
const uint32 HardcodedVideoBitrate = 20000000;
const uint32 MinVideoBitrate = 1000000;
const uint32 MaxVideoBitrate = 20000000;
const uint32 MinVideoFPS = 10;
const uint32 MaxVideoFPS = 60;

const uint32 MaxWidth = 1920;
const uint32 MaxHeight = 1080;

FAutoConsoleCommand GameplayMediaEncoderInitialize(
	TEXT("GameplayMediaEncoder.Initialize"),
	TEXT("Constructs the audio/video encoding objects. Does not start encoding"),
	FConsoleCommandDelegate::CreateStatic(&FGameplayMediaEncoder::InitializeCmd)
);

FAutoConsoleCommand GameplayMediaEncoderStart(
	TEXT("GameplayMediaEncoder.Start"),
	TEXT("Starts encoding"),
	FConsoleCommandDelegate::CreateStatic(&FGameplayMediaEncoder::StartCmd)
);

FAutoConsoleCommand GameplayMediaEncoderStop(
	TEXT("GameplayMediaEncoder.Stop"),
	TEXT("Stops encoding"),
	FConsoleCommandDelegate::CreateStatic(&FGameplayMediaEncoder::StopCmd)
);

FAutoConsoleCommand GameplayMediaEncoderShutdown(
	TEXT("GameplayMediaEncoder.Shutdown"),
	TEXT("Releases all systems."),
	FConsoleCommandDelegate::CreateStatic(&FGameplayMediaEncoder::ShutdownCmd)
);

//////////////////////////////////////////////////////////////////////////
//
// FGameplayMediaEncoder
//
//////////////////////////////////////////////////////////////////////////

FGameplayMediaEncoder* FGameplayMediaEncoder::Singleton = nullptr;

FGameplayMediaEncoder* FGameplayMediaEncoder::Get()
{
	if (!Singleton)
	{
		Singleton = new FGameplayMediaEncoder();
	}
	return Singleton;
}

FGameplayMediaEncoder::FGameplayMediaEncoder()
{
}

FGameplayMediaEncoder::~FGameplayMediaEncoder()
{
	Shutdown();
}

bool FGameplayMediaEncoder::RegisterListener(IGameplayMediaEncoderListener* Listener)
{
	check(IsInGameThread());
	FScopeLock Lock(&ListenersCS);

	if (Listeners.Num() == 0)
	{
		UE_LOG(GameplayMediaEncoder, Log, TEXT("Registering the first listener"));
		if (!Start())
		{
			return false;
		}
	}

	Listeners.AddUnique(Listener);
	return true;
}

void FGameplayMediaEncoder::UnregisterListener(IGameplayMediaEncoderListener* Listener)
{
	check(IsInGameThread());

	ListenersCS.Lock();
	Listeners.Remove(Listener);
	bool bAnyListenersLeft = Listeners.Num() > 0;
	ListenersCS.Unlock();

	if (bAnyListenersLeft == false)
	{
		UE_LOG(GameplayMediaEncoder, Log, TEXT("Unregistered the last listener"));
		Stop();
	}
}

bool FGameplayMediaEncoder::Initialize()
{
	MemoryCheckpoint("Initial");

	if (VideoEncoder)
	{
		UE_LOG(GameplayMediaEncoder, Log, TEXT("Already initialized"));
		return true;
	}

	// If some error occurs, call Shutdown to cleanup
	bool bIsOk = false;
	ON_SCOPE_EXIT
	{
		if (!bIsOk)
		{
			Shutdown();
		}
	};

	//
	// Audio
	//
	AVEncoder::FAudioEncoderFactory* AudioEncoderFactory = AVEncoder::FAudioEncoderFactory::FindFactory("aac");
	if (!AudioEncoderFactory)
	{
		UE_LOG(GameplayMediaEncoder, Error, TEXT("No audio encoder for aac found"));
		return false;
	}

	AudioEncoder = AudioEncoderFactory->CreateEncoder("aac");
	if (!AudioEncoder)
	{
		UE_LOG(GameplayMediaEncoder, Error, TEXT("Could not create audio encoder"));
		return false;
	}

	AVEncoder::FAudioConfig AudioConfig;
	AudioConfig.Samplerate = HardcodedAudioSamplerate;
	AudioConfig.NumChannels = HardcodedAudioNumChannels;
	AudioConfig.Bitrate = HardcodedAudioBitrate;
	if (!AudioEncoder->Initialize(AudioConfig))
	{
		UE_LOG(GameplayMediaEncoder, Error, TEXT("Could not initialize audio encoder"));
		return false;
	}

	AudioEncoder->RegisterListener(*this);

	MemoryCheckpoint("Audio encoder initialized");

	//
	// Video
	//

	VideoConfig.Codec = "h264";
	VideoConfig.Height = VideoConfig.Width = VideoConfig.Framerate = VideoConfig.Bitrate = 0;
	FParse::Value(FCommandLine::Get(), TEXT("GameplayMediaEncoder.ResY="), VideoConfig.Height);
	UE_LOG(GameplayMediaEncoder, Log, TEXT("GameplayMediaEncoder.ResY = %d"), VideoConfig.Height);
	if (VideoConfig.Height == 0 || VideoConfig.Height == 720)
	{
		VideoConfig.Width = 1280;
		VideoConfig.Height = 720;
	}
	else if (VideoConfig.Height == 1080)
	{
		VideoConfig.Width = 1920;
		VideoConfig.Height = 1080;
	}
	else
	{
		UE_LOG(GameplayMediaEncoder, Fatal, TEXT("GameplayMediaEncoder.ResY can only have a value of 720 or 1080"));
		return false;
	}

	// Specifying 0 will completely disable frame skipping (therefore encoding as many frames as possible)
	FParse::Value(FCommandLine::Get(), TEXT("GameplayMediaEncoder.FPS="), VideoConfig.Framerate);
	if (VideoConfig.Framerate == 0)
	{
		// Note : When disabling frame skipping, we lie to the encoder when initializing.
		// We still specify a framerate, but then feed frames without skipping
		VideoConfig.Framerate = HardcodedVideoFPS;
		bDoFrameSkipping = false;
		UE_LOG(GameplayMediaEncoder, Log, TEXT("Uncapping FPS"));
	}
	else
	{
		VideoConfig.Framerate = FMath::Clamp(VideoConfig.Framerate, (uint32)MinVideoFPS, (uint32)MaxVideoFPS);
		bDoFrameSkipping = true;
		UE_LOG(GameplayMediaEncoder, Log, TEXT("Capping FPS %u"), VideoConfig.Framerate);
	}

	VideoConfig.Bitrate = HardcodedVideoBitrate;
	FParse::Value(FCommandLine::Get(), TEXT("GameplayMediaEncoder.Bitrate="), VideoConfig.Bitrate);
	VideoConfig.Bitrate = FMath::Clamp(VideoConfig.Bitrate, (uint32)MinVideoBitrate, (uint32)MaxVideoBitrate);

	AVEncoder::FVideoEncoder::FLayerConfig videoInit;
	videoInit.Width = VideoConfig.Width;
	videoInit.Height = VideoConfig.Height;
	videoInit.MaxBitrate = MaxVideoBitrate;
	videoInit.TargetBitrate = VideoConfig.Bitrate;
	videoInit.MaxFramerate = VideoConfig.Framerate;

	if (GDynamicRHI)
	{
		FString RHIName = GDynamicRHI->GetName();

#if PLATFORM_WINDOWS
		if (RHIName == TEXT("D3D11"))
			VideoEncoderInput = AVEncoder::FVideoEncoderInput::CreateForD3D11(GDynamicRHI->RHIGetNativeDevice(), VideoConfig.Width, VideoConfig.Height, true);
		else if (RHIName == TEXT("D3D12"))
			VideoEncoderInput = AVEncoder::FVideoEncoderInput::CreateForD3D12(GDynamicRHI->RHIGetNativeDevice(), VideoConfig.Width, VideoConfig.Height, true);
		else
#endif
#if WITH_CUDA
			VideoEncoderInput = AVEncoder::FVideoEncoderInput::CreateForCUDA(FModuleManager::GetModuleChecked<FCUDAModule>("CUDA").GetCudaContext(), VideoConfig.Width, VideoConfig.Height, true);
#else
			unimplemented();
#endif
	}

	auto& Available = AVEncoder::FVideoEncoderFactory::Get().GetAvailable();
	VideoEncoder = AVEncoder::FVideoEncoderFactory::Get().Create(Available[0].ID, VideoEncoderInput, videoInit);
	VideoEncoder->SetOnEncodedPacket([this](uint32 LayerIndex, const AVEncoder::FVideoEncoderInputFrame* Frame, const AVEncoder::FCodecPacket& Packet) {
		OnEncodedVideoFrame(LayerIndex, Frame, Packet);
	});
	
	if (!VideoEncoder)
	{
		UE_LOG(GameplayMediaEncoder, Error, TEXT("Could not create video encoder"));
		return false;
	}

	MemoryCheckpoint("Video encoder initialized");

	bIsOk = true; // So Shutdown is not called due to the ON_SCOPE_EXIT
	return true;
}

bool FGameplayMediaEncoder::Start()
{
	if (StartTime != 0)
	{
		UE_LOG(GameplayMediaEncoder, Log, TEXT("Already running"));
		return true;
	}

	if (!VideoEncoder)
	{
		UE_LOG(GameplayMediaEncoder, Log, TEXT("Not initialized yet , so also performing a Intialize()"));
		if (!Initialize())
		{
			return false;
		}
	}

	StartTime = FTimespan::FromSeconds(FPlatformTime::Seconds());
	AudioClock = 0;
	NumCapturedFrames = 0;
	
	//
	// subscribe to engine delegates for audio output and back buffer
	//

	FAudioDeviceHandle AudioDevice = GEngine->GetMainAudioDevice();
	if (AudioDevice)
	{
		bAudioFormatChecked = false;
		AudioDevice->RegisterSubmixBufferListener(this);
	}

	FSlateApplication::Get().GetRenderer()->OnBackBufferReadyToPresent().AddRaw(this, &FGameplayMediaEncoder::OnFrameBufferReady);

	return true;
}

void FGameplayMediaEncoder::Stop()
{
	check(IsInGameThread());

	if (StartTime == 0)
	{
		UE_LOG(GameplayMediaEncoder, Log, TEXT("Not running"));
		return;
	}

	if (UGameEngine* GameEngine = Cast<UGameEngine>(GEngine))
	{
		FAudioDevice* AudioDevice = GameEngine->GetMainAudioDeviceRaw();
		if (AudioDevice)
		{
			AudioDevice->UnregisterSubmixBufferListener(this);
		}

		if (FSlateApplication::IsInitialized())
		{
			FSlateApplication::Get().GetRenderer()->OnBackBufferReadyToPresent().RemoveAll(this);
		}
	}

	StartTime = 0;
	AudioClock = 0;
}

AVEncoder::FAudioConfig FGameplayMediaEncoder::GetAudioConfig() const
{
	if (AudioEncoder)
	{
		auto codec = AudioEncoder->GetType();
		auto config = AudioEncoder->GetConfig();
		return { codec, config.Samplerate, config.NumChannels, config.Bitrate };
	}
	else
	{
		return {};
	}
}

void FGameplayMediaEncoder::Shutdown()
{
	if (StartTime != 0)
	{
		UE_LOG(GameplayMediaEncoder, Log, TEXT("Currently running, so also performing a Stop()"));
		Stop();
	}

	{
		FScopeLock Lock(&AudioProcessingCS);
		if (AudioEncoder)
		{
			//AudioEncoder->Reset();
			AudioEncoder->Shutdown();
			AudioEncoder.Reset();
		}
	}
	{
		FScopeLock Lock(&VideoProcessingCS);
		if (VideoEncoder)
		{
			VideoEncoder->Shutdown();
			VideoEncoder.Reset();

			BackBuffers.Empty();
		}
	}

}

FTimespan FGameplayMediaEncoder::GetMediaTimestamp() const
{
	return FTimespan::FromSeconds(FPlatformTime::Seconds()) - StartTime;
}

void FGameplayMediaEncoder::OnNewSubmixBuffer(const USoundSubmix* OwningSubmix, float* AudioData, int32 NumSamples, int32 NumChannels, const int32 SampleRate, double /*AudioClock*/)
{
	CSV_SCOPED_TIMING_STAT(GameplayMediaEncoder, OnNewSubmixBuffer);
	if (SampleRate != HardcodedAudioSamplerate)
	{
		// Only report the problem once
		if (!bAudioFormatChecked)
		{
			bAudioFormatChecked = true;
			UE_LOG(GameplayMediaEncoder, Error, TEXT("Audio SampleRate needs to be %d HZ, current value is %d. VideoRecordingSystem won't record audio"), HardcodedAudioSamplerate, SampleRate);
		}
		return;
	}

	ProcessAudioFrame(AudioData, NumSamples, NumChannels, SampleRate);
}

void FGameplayMediaEncoder::OnFrameBufferReady(SWindow& SlateWindow, const FTexture2DRHIRef& FrameBuffer)
{
	CSV_SCOPED_TIMING_STAT(GameplayMediaEncoder, OnBackBufferReady);
	check(IsInRenderingThread());
	ProcessVideoFrame(FrameBuffer);
}

void FGameplayMediaEncoder::FloatToPCM16(float const* floatSamples, int32 numSamples, TArray<int16>& out) const
{
	out.Reset(numSamples);
	out.AddZeroed(numSamples);

	float const* ptr = floatSamples;
	for (auto&& sample : out)
	{
		int32 N = *ptr >= 0 ? *ptr * int32(MAX_int16) : *ptr * (int32(MAX_int16) + 1);
		sample = static_cast<int16>(FMath::Clamp(N, int32(MIN_int16), int32(MAX_int16)));
		ptr++;
	}
}

void FGameplayMediaEncoder::ProcessAudioFrame(const float* AudioData, int32 NumSamples, int32 NumChannels, int32 SampleRate)
{
	//// convert to PCM data
	//TArray<int16> conversionBuffer;
	//FloatToPCM16(AudioData, NumSamples, conversionBuffer);

	//// add to any remainder data
	//PCM16.Append(conversionBuffer);

	//// encode the 10ms blocks
	//size_t const encodeBlockSize = AudioConfig.Samplerate / 100 * AudioConfig.NumChannels;
	//int32 bufferSize = PCM16.Num();
	//auto timestamp = GetMediaTimestamp().GetTicks();
	//auto bufferStart = PCM16.GetData();

	//while (bufferSize >= encodeBlockSize)
	//{
	//	rtc::Buffer encoded;
	//	auto encodedInfo = AudioEncoder->Encode(timestamp, { bufferStart, encodeBlockSize }, &encoded);
	//	if (encodedInfo.encoded_bytes > 0 || encodedInfo.send_even_if_empty)
	//		OnEncodedAudioFrame(encodedInfo, &encoded);
	//	timestamp += 10 * ETimespan::TicksPerMillisecond;
	//	bufferStart += encodeBlockSize;
	//	bufferSize -= encodeBlockSize;
	//}

	//// move the remainder to the start of the buffer
	//int32 const remainderIdx = bufferStart - PCM16.GetData();
	//for (int32 i = 0; i < bufferSize; ++i)
	//{
	//	PCM16[i] = PCM16[remainderIdx + i];
	//}
	//PCM16.SetNum(bufferSize, false);
	
	Audio::AlignedFloatBuffer InData;
	InData.Append(AudioData, NumSamples);
	Audio::TSampleBuffer<float> FloatBuffer(InData, NumChannels, SampleRate);

	// Mix to stereo if required, since PixelStreaming only accept stereo at the moment
	if (FloatBuffer.GetNumChannels() != HardcodedAudioNumChannels)
	{
		FloatBuffer.MixBufferToChannels(HardcodedAudioNumChannels);
	}

	// Adjust the AudioClock if for some reason it falls behind real time. This can happen if the game spikes, or if we break into the debugger.
	FTimespan Now = GetMediaTimestamp();
	if (AudioClock < Now.GetTotalSeconds())
	{
		UE_LOG(GameplayMediaEncoder, Warning, TEXT("Audio clock falling behind real time clock by %.3f seconds. Ajusting audio clock"), Now.GetTotalSeconds()-AudioClock);
		// Put it slightly ahead of the real time clock
		AudioClock = Now.GetTotalSeconds() + (FloatBuffer.GetSampleDuration() / 2);
	}

	// Convert to signed PCM 16-bits
	//PCM16.Reset(FloatBuffer.GetNumSamples());
	//PCM16.AddZeroed(FloatBuffer.GetNumSamples());
	//int blockSize = AudioConfig.Samplerate / 100 * AudioConfig.NumChannels;
	//PCM16.Reset(blockSize);
	//PCM16.AddZeroed(blockSize);
	//const float* Ptr = reinterpret_cast<const float*>(FloatBuffer.GetData());
	//auto timestamp = GetMediaTimestamp().GetTotalMilliseconds();
	//for (int i = 0; i < NumSamples * NumChannels; ++i)
	//{
	//	int u;
	//	for (u = 0; u < blockSize && i < NumSamples; ++u, ++i, ++Ptr)
	//	{
	//		int32 N = *Ptr >= 0 ? *Ptr * int32(MAX_int16) : *Ptr * (int32(MAX_int16) + 1);
	//		PCM16[u] = static_cast<int16>(FMath::Clamp(N, int32(MIN_int16), int32(MAX_int16)));
	//	}

	//	rtc::Buffer encoded;
	//	auto encodedInfo = AudioEncoder->Encode(timestamp, { PCM16.GetData(), static_cast<size_t>(u) }, &encoded);
	//	OnEncodedAudioFrame(encodedInfo, &encoded);
	//	timestamp += 10;
	//}

	//for (int16& S : PCM16)
	//{
	//	int32 N = *Ptr >= 0 ? *Ptr * int32(MAX_int16) : *Ptr * (int32(MAX_int16) + 1);
	//	S = static_cast<int16>(FMath::Clamp(N, int32(MIN_int16), int32(MAX_int16)));
	//	Ptr++;
	//}

	////rtc::ArrayView<const int16_t> audio(PCM16.GetData(), FloatBuffer.GetNumSamples());
	//rtc::ArrayView<const int16_t> audio(PCM16.GetData(), blockSize);
	//auto testSampleRate = AudioEncoder->SampleRateHz();
	//auto testNumChannels = AudioEncoder->NumChannels();
	//check(testSampleRate == AudioConfig.Samplerate);
	//check(testNumChannels == AudioConfig.NumChannels);
	//auto timestamp = GetMediaTimestamp().GetTotalMilliseconds();
	//auto encodedInfo = AudioEncoder->Encode(timestamp, audio, &encoded);
	//OnEncodedAudioFrame(encodedInfo, &encoded);

	AVEncoder::FAudioFrame Frame;
	Frame.Timestamp = FTimespan::FromSeconds(AudioClock);
	Frame.Duration = FTimespan::FromSeconds(FloatBuffer.GetSampleDuration());
	FloatBuffer.Clamp();
	Frame.Data = FloatBuffer;
	AudioEncoder->Encode(Frame);

	AudioClock += FloatBuffer.GetSampleDuration();
}

void FGameplayMediaEncoder::ProcessVideoFrame(const FTexture2DRHIRef& FrameBuffer)
{
	FScopeLock Lock(&VideoProcessingCS);

	FTimespan Now = GetMediaTimestamp();

	if (bDoFrameSkipping)
	{
		uint64 NumExpectedFrames = static_cast<uint64>(Now.GetTotalSeconds() * VideoConfig.Framerate);
		UE_LOG(GameplayMediaEncoder, VeryVerbose, TEXT("time %.3f: captured %d, expected %d"), Now.GetTotalSeconds(), NumCapturedFrames + 1, NumExpectedFrames);
		if (NumCapturedFrames + 1 > NumExpectedFrames)
		{
			UE_LOG(GameplayMediaEncoder, Verbose, TEXT("Framerate control dropped captured frame"));
			return;
		}
	}

	UpdateVideoConfig();

	AVEncoder::FVideoEncoderInputFrame* InputFrame = ObtainInputFrame();
	const int32 FrameId = InputFrame->GetFrameID();
	InputFrame->SetTimestampUs(Now.GetTicks());

	CopyTexture(FrameBuffer, BackBuffers[InputFrame]);

	AVEncoder::FVideoEncoder::FEncodeOptions EncodeOptions;
	VideoEncoder->Encode(InputFrame, EncodeOptions);

	LastVideoInputTimestamp = Now;
	NumCapturedFrames++;
}

AVEncoder::FVideoEncoderInputFrame* FGameplayMediaEncoder::ObtainInputFrame()
{
	AVEncoder::FVideoEncoderInputFrame* InputFrame = VideoEncoderInput->ObtainInputFrame();

	if (!BackBuffers.Contains(InputFrame))
	{
#if PLATFORM_WINDOWS
		FString RHIName = GDynamicRHI->GetName();
		if (RHIName == TEXT("D3D11"))
		{
			FRHIResourceCreateInfo CreateInfo(TEXT("VideoCapturerBackBuffer"));
			FTexture2DRHIRef Texture = GDynamicRHI->RHICreateTexture2D(VideoConfig.Width, VideoConfig.Height, EPixelFormat::PF_B8G8R8A8, 1, 1, TexCreate_Shared | TexCreate_RenderTargetable | TexCreate_UAV, ERHIAccess::CopyDest, CreateInfo);
			InputFrame->SetTexture((ID3D11Texture2D*)Texture->GetNativeResource(), [&, InputFrame](ID3D11Texture2D* NativeTexture) { BackBuffers.Remove(InputFrame); });
			BackBuffers.Add(InputFrame, Texture);
		}
		else if (RHIName == TEXT("D3D12"))
		{
			FRHIResourceCreateInfo CreateInfo(TEXT("VideoCapturerBackBuffer"));
			FTexture2DRHIRef Texture = GDynamicRHI->RHICreateTexture2D(VideoConfig.Width, VideoConfig.Height, EPixelFormat::PF_B8G8R8A8, 1, 1, TexCreate_Shared | TexCreate_RenderTargetable | TexCreate_UAV, ERHIAccess::CopyDest, CreateInfo);
			InputFrame->SetTexture((ID3D12Resource*)Texture->GetNativeResource(), [&, InputFrame](ID3D12Resource* NativeTexture) { BackBuffers.Remove(InputFrame); });
			BackBuffers.Add(InputFrame, Texture);
		}
#endif // PLATFORM_WINDOWS
#if WITH_CUDA
#if PLATFORM_WINDOWS
		else if (RHIName == TEXT("Vulkan"))
#endif // PLATFORM_WINDOWS
		{
			FRHIResourceCreateInfo CreateInfo(TEXT("VideoCapturerBackBuffer"));

			// TODO (M84FIX) Replace with CUDA texture
			// Create a texture that can be exposed to external memory
			FTexture2DRHIRef Texture = GDynamicRHI->RHICreateTexture2D(VideoConfig.Width, VideoConfig.Height, EPixelFormat::PF_B8G8R8A8, 1, 1, TexCreate_Shared | TexCreate_RenderTargetable | TexCreate_UAV, ERHIAccess::CopyDest, CreateInfo);

			FVulkanTexture2D* VulkanTexture = static_cast<FVulkanTexture2D*>(Texture.GetReference());

			FVulkanDynamicRHI* device = static_cast<FVulkanDynamicRHI*>(GDynamicRHI)->GetDevice()->GetInstanceHandle();

			// Get the CUarray to that textures memory making sure the clear it when done
			int fd;

			{    // Generate VkMemoryGetFdInfoKHR
				VkMemoryGetFdInfoKHR vkMemoryGetFdInfoKHR = {};
				vkMemoryGetFdInfoKHR.sType = VK_STRUCTURE_TYPE_MEMORY_GET_FD_INFO_KHR;
				vkMemoryGetFdInfoKHR.pNext = NULL;
				vkMemoryGetFdInfoKHR.memory = VulkanTexture->Surface.GetAllocationHandle();
				vkMemoryGetFdInfoKHR.handleType =
					VK_EXTERNAL_MEMORY_HANDLE_TYPE_OPAQUE_FD_BIT_KHR;

				auto fpGetMemoryFdKHR = (PFN_vkGetMemoryFdKHR)VulkanRHI::vkGetDeviceProcAddr(device, "vkGetMemoryFdKHR");
				VERIFYVULKANRESULT(fpGetMemoryFdKHR(device, &vkMemoryGetFdInfoKHR, &fd));
			}

			cuCtxPushCurrent(FModuleManager::GetModuleChecked<FCUDAModule>("CUDA").GetCudaContext());

			CUexternalMemory mappedExternalMemory = nullptr;

			{
				// generate a cudaExternalMemoryHandleDesc
				CUDA_EXTERNAL_MEMORY_HANDLE_DESC cudaExtMemHandleDesc = {};
				cudaExtMemHandleDesc.type = CU_EXTERNAL_MEMORY_HANDLE_TYPE_OPAQUE_FD;
				cudaExtMemHandleDesc.handle.fd = fd;
				cudaExtMemHandleDesc.size = VulkanTexture->Surface.GetAllocationOffset() + VulkanTexture->Surface.GetMemorySize();

				// import external memory
				auto result = cuImportExternalMemory(&mappedExternalMemory, &cudaExtMemHandleDesc);
				if (result != CUDA_SUCCESS)
				{
					UE_LOG(PixelStreamer, Error, TEXT("Failed to import external memory from vulkan error: %d"), result);
				}
			}

			CUmipmappedArray mappedMipArray = nullptr;
			CUarray mappedArray = nullptr;

			{
				CUDA_EXTERNAL_MEMORY_MIPMAPPED_ARRAY_DESC mipmapDesc = {};
				mipmapDesc.numLevels = 1;
				mipmapDesc.offset = VulkanTexture->Surface.GetAllocationOffset();
				mipmapDesc.arrayDesc.Width = Texture->GetSizeX();
				mipmapDesc.arrayDesc.Height = Texture->GetSizeY();
				mipmapDesc.arrayDesc.Depth = 0;
				mipmapDesc.arrayDesc.NumChannels = 4;
				mipmapDesc.arrayDesc.Format = CU_AD_FORMAT_UNSIGNED_INT8;
				mipmapDesc.arrayDesc.Flags = CUDA_ARRAY3D_SURFACE_LDST | CUDA_ARRAY3D_COLOR_ATTACHMENT;

				// get the CUarray from the external memory
				auto result = cuExternalMemoryGetMappedMipmappedArray(&mappedMipArray, mappedExternalMemory, &mipmapDesc);
				if (result != CUDA_SUCCESS)
				{
					UE_LOG(PixelStreamer, Error, TEXT("Failed to bind mipmappedArray error: %d"), result);
				}
			}

			// get the CUarray from the external memory
			CUresult mipMapArrGetLevelErr = cuMipmappedArrayGetLevel(&mappedArray, mappedMipArray, 0);
			if (mipMapArrGetLevelErr != CUDA_SUCCESS)
			{
				UE_LOG(PixelStreamer, Error, TEXT("Failed to bind to mip 0."));
			}

			cuCtxPopCurrent(NULL);

			InputFrame->SetTexture(mappedArray, [&, InputFrame](CUarray NativeTexture)
				{
					// free the cuda types
					cuCtxPushCurrent(FModuleManager::GetModuleChecked<FCUDAModule>("CUDA").GetCudaContext());

					if (mappedArray)
					{
						cuArrayDestroy(mappedArray);
					}
					if (mappedMipArray)
					{
						cuMipmappedArrayDestroy(mappedMipArray);
					}
					if (mappedExternalMemory)
					{
						cuDestroyExternalMemory(mappedExternalMemory);
					}

					cuCtxPopCurrent(NULL);

					// finally remove the input frame
					BackBuffers.Remove(InputFrame);
				});
			BackBuffers.Add(InputFrame, Texture);
		}
#endif // WITH_CUDA

		UE_LOG(LogTemp, Log, TEXT("%d backbuffers currently allocated"), BackBuffers.Num());
	}

	return InputFrame;
}

void FGameplayMediaEncoder::SetVideoBitrate(uint32 Bitrate)
{
	NewVideoBitrate = Bitrate;
	bChangeBitrate = true;
}

void FGameplayMediaEncoder::SetVideoFramerate(uint32 Framerate)
{
	NewVideoFramerate = FMath::Clamp(Framerate, MinVideoFPS, MaxVideoFPS);
	bChangeFramerate = true;
}

void FGameplayMediaEncoder::UpdateVideoConfig()
{
	if (bChangeBitrate || bChangeFramerate)
	{
		auto config = VideoEncoder->GetLayerConfig(0);

		if (bChangeBitrate)
		{
			config.MaxBitrate = MaxVideoBitrate;
			config.TargetBitrate = NewVideoBitrate;
		}

		if (bChangeFramerate)
		{
			config.MaxFramerate = NewVideoFramerate;
			NumCapturedFrames = 0;
		}

		VideoEncoder->UpdateLayerConfig(0, config);
		bChangeFramerate = false;
		bChangeBitrate = false;
	}
}

void FGameplayMediaEncoder::OnEncodedAudioFrame(const AVEncoder::FMediaPacket& Packet)
{

	FScopeLock Lock(&ListenersCS);
	for (auto&& Listener : Listeners)
	{
		Listener->OnMediaSample(Packet);
	}
}

void FGameplayMediaEncoder::OnEncodedVideoFrame(uint32 LayerIndex, const AVEncoder::FVideoEncoderInputFrame* InputFrame, const AVEncoder::FCodecPacket& Packet)
{
	AVEncoder::FMediaPacket packet(AVEncoder::EPacketType::Video);

	packet.Timestamp = InputFrame->GetTimestampUs();
	packet.Duration = 0; // This should probably be 1.0f / fps in ms
	packet.Data = TArray<uint8>(Packet.Data, Packet.DataSize);
	packet.Video.bKeyFrame = Packet.IsKeyFrame;
	packet.Video.Width = InputFrame->GetWidth();
	packet.Video.Height = InputFrame->GetHeight();
	packet.Video.FrameAvgQP = Packet.VideoQP;
	packet.Video.Framerate = VideoConfig.Framerate;

	FScopeLock Lock(&ListenersCS);
	for (auto&& Listener : Listeners)
	{
		Listener->OnMediaSample(packet);
	}

	InputFrame->Release();
}

void FGameplayMediaEncoder::CopyTexture(const FTexture2DRHIRef& SourceTexture, FTexture2DRHIRef& DestinationTexture) const
{
	FRHICommandListImmediate& RHICmdList = FRHICommandListExecutor::GetImmediateCommandList();

	if (SourceTexture->GetFormat() == DestinationTexture->GetFormat() &&
		SourceTexture->GetSizeXY() == DestinationTexture->GetSizeXY())
	{
		RHICmdList.CopyToResolveTarget(SourceTexture, DestinationTexture, FResolveParams{});
	}
	else // Texture format mismatch, use a shader to do the copy.
	{
		IRendererModule* RendererModule = &FModuleManager::GetModuleChecked<IRendererModule>("Renderer");

		// #todo-renderpasses there's no explicit resolve here? Do we need one?
		FRHIRenderPassInfo RPInfo(DestinationTexture, ERenderTargetActions::Load_Store);

		RHICmdList.BeginRenderPass(RPInfo, TEXT("CopyBackbuffer"));

		{
			RHICmdList.SetViewport(0, 0, 0.0f, DestinationTexture->GetSizeX(), DestinationTexture->GetSizeY(), 1.0f);

			FGraphicsPipelineStateInitializer GraphicsPSOInit;
			RHICmdList.ApplyCachedRenderTargets(GraphicsPSOInit);
			GraphicsPSOInit.BlendState = TStaticBlendState<>::GetRHI();
			GraphicsPSOInit.RasterizerState = TStaticRasterizerState<>::GetRHI();
			GraphicsPSOInit.DepthStencilState = TStaticDepthStencilState<false, CF_Always>::GetRHI();

			// New engine version...
			FGlobalShaderMap* ShaderMap = GetGlobalShaderMap(GMaxRHIFeatureLevel);
			TShaderMapRef<FScreenVS> VertexShader(ShaderMap);
			TShaderMapRef<FScreenPS> PixelShader(ShaderMap);

			GraphicsPSOInit.BoundShaderState.VertexDeclarationRHI = GFilterVertexDeclaration.VertexDeclarationRHI;
			GraphicsPSOInit.BoundShaderState.VertexShaderRHI = VertexShader.GetVertexShader();
			GraphicsPSOInit.BoundShaderState.PixelShaderRHI = PixelShader.GetPixelShader();

			GraphicsPSOInit.PrimitiveType = PT_TriangleList;

			SetGraphicsPipelineState(RHICmdList, GraphicsPSOInit, 0);

			if (DestinationTexture->GetSizeX() != SourceTexture->GetSizeX() || DestinationTexture->GetSizeY() != SourceTexture->GetSizeY())
			{
				PixelShader->SetParameters(RHICmdList, TStaticSamplerState<SF_Bilinear>::GetRHI(), SourceTexture);
			}
			else
			{
				PixelShader->SetParameters(RHICmdList, TStaticSamplerState<SF_Point>::GetRHI(), SourceTexture);
			}

			RendererModule->DrawRectangle(
				RHICmdList,
				0, 0,									// Dest X, Y
				DestinationTexture->GetSizeX(),			// Dest Width
				DestinationTexture->GetSizeY(),			// Dest Height
				0, 0,									// Source U, V
				1, 1,									// Source USize, VSize
				DestinationTexture->GetSizeXY(),		// Target buffer size
				FIntPoint(1, 1),						// Source texture size
				VertexShader,
				EDRF_Default);
		}

		RHICmdList.EndRenderPass();
	}
}