Add initial project files and implement basic audio-visual recording functionality

Build/Mac/AudioVideoRecord.PackageVersionCounter

@@ -0,0 +1 @@
+0.3

Build/Mac/Resources/Info.Template.plist

@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>NSAppTransportSecurity</key>
+	<dict>
+		<key>NSAllowsArbitraryLoads</key>
+		<true/>
+	</dict>
+	<key>NSHighResolutionCapable</key>
+	<false/>
+	<key>ITSAppUsesNonExemptEncryption</key>
+	<false/>
+</dict>
+</plist>

Build/Mac/Resources/Sandbox.NoNet.entitlements

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>com.apple.security.app-sandbox</key>
+	<true/>
+</dict>
+</plist>

Build/Mac/Resources/Sandbox.Server.entitlements

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>com.apple.security.app-sandbox</key>
+	<true/>
+	<key>com.apple.security.network.client</key>
+	<true/>
+	<key>com.apple.security.network.server</key>
+	<true/>
+</dict>
+</plist>

Source/AudioVideoRecord/AudioVideoRecordGameMode.cpp

@@ -1,8 +1,23 @@
 // Copyright Epic Games, Inc. All Rights Reserved.
 
 #include "AudioVideoRecordGameMode.h"
+#include "Kismet/GameplayStatics.h"
+#include "Components/AudioComponent.h"
 
 AAudioVideoRecordGameMode::AAudioVideoRecordGameMode()
 {
-	// stub
+}
+
+void AAudioVideoRecordGameMode::BeginPlay()
+{
+	Super::BeginPlay();
+
+	if (BGMSound)
+	{
+		BGMAudioComponent = UGameplayStatics::SpawnSound2D(this, BGMSound, BGMVolume);
+		if (BGMAudioComponent)
+		{
+			BGMAudioComponent->bAutoDestroy = false;
+		}
+	}
 }

Source/AudioVideoRecord/AudioVideoRecordGameMode.h

@@ -6,6 +6,9 @@
 #include "GameFramework/GameModeBase.h"
 #include "AudioVideoRecordGameMode.generated.h"
 
+class USoundBase;
+class UAudioComponent;
+
 /**
  *  Simple GameMode for a first person game
  */
@@ -16,6 +19,21 @@ class AAudioVideoRecordGameMode : public AGameModeBase
 
 public:
 	AAudioVideoRecordGameMode();
+
+	/** Background music to play when the level starts. Assign in Blueprint. */
+	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Audio")
+	USoundBase* BGMSound = nullptr;
+
+	/** Volume multiplier for BGM (0.0 – 1.0). */
+	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Audio", meta = (ClampMin = "0.0", ClampMax = "1.0"))
+	float BGMVolume = 0.5f;
+
+protected:
+	virtual void BeginPlay() override;
+
+private:
+	UPROPERTY()
+	UAudioComponent* BGMAudioComponent = nullptr;
 };
 
 

Source/AudioVideoRecord/SimpleRecorder.cpp

@@ -118,81 +118,17 @@ void USimpleRecorder::StartRecording()
 
 	InitOutputPaths();
 	bIsRecording = true;
-
+	bFFmpegStarted = false;
-	// ─── 0. Auto-detect viewport size if not explicitly set ─────────
-	if (bAutoDetectResolution)
-	{
-		if (GEngine && GEngine->GameViewport)
-		{
-			FVector2D ViewportSize;
-			GEngine->GameViewport->GetViewportSize(ViewportSize);
-			if (ViewportSize.X > 0 && ViewportSize.Y > 0)
-			{
-				CaptureWidth  = FMath::RoundToInt32(ViewportSize.X);
-				CaptureHeight = FMath::RoundToInt32(ViewportSize.Y);
-				// Ensure even dimensions (required by most video encoders)
-				CaptureWidth  = CaptureWidth  & ~1;
-				CaptureHeight = CaptureHeight & ~1;
-			}
-		}
-	}
 
 	UE_LOG(LogAudioVideoRecord, Log, TEXT("SimpleRecorder: Starting recording..."));
-	UE_LOG(LogAudioVideoRecord, Log, TEXT("  Resolution: %dx%d @ %d FPS"), CaptureWidth, CaptureHeight, CaptureFPS);
 	UE_LOG(LogAudioVideoRecord, Log, TEXT("  Video → %s"), *VideoFilePath);
 	UE_LOG(LogAudioVideoRecord, Log, TEXT("  Audio → %s"), *AudioFilePath);
 	UE_LOG(LogAudioVideoRecord, Log, TEXT("  Final → %s"), *FinalFilePath);
+	UE_LOG(LogAudioVideoRecord, Log, TEXT("  FFmpeg pipe will start on first frame (actual back-buffer size)."));
 
-	// ─── 1. Open FFmpeg video pipe ──────────────────────────────────
+	// ─── 1. Register back-buffer delegate (video frames) ────────────
-	{
+	// FFmpeg is NOT started here — it launches on the first frame
-		FString FFmpeg = GetFFmpegExecutable();
+	// so we can read the real back-buffer dimensions.
-
-		// Build command:
-		//   ffmpeg  -y  -f rawvideo -pix_fmt bgra
-		//           -video_size WxH -framerate FPS
-		//           -i -             (stdin)
-		//           -c:v <encoder> ...  -b:v BITRATE
-		//           output.mp4
-		//
-		// Encoder selection per platform:
-		//   Mac:     h264_videotoolbox (Apple HW encoder)
-		//   Windows: h264_nvenc / h264_amf / h264_qsv (detected at runtime)
-		//   Linux:   libx264 (software fallback)
-#if PLATFORM_MAC
-		FString EncoderFlags = FString::Printf(TEXT("-c:v h264_videotoolbox -b:v %s"), *VideoBitrate);
-#elif PLATFORM_WINDOWS
-		FString EncoderFlags = FString::Printf(TEXT("-c:v h264_nvenc -preset p5 -b:v %s"), *VideoBitrate);
-#else
-		FString EncoderFlags = FString::Printf(TEXT("-c:v libx264 -preset medium -b:v %s"), *VideoBitrate);
-#endif
-
-		FString Cmd = FString::Printf(
-			TEXT("\"%s\" -y -f rawvideo -pix_fmt bgra -video_size %dx%d -framerate %d ")
-			TEXT("-i - %s \"%s\""),
-			*FFmpeg,
-			CaptureWidth, CaptureHeight, CaptureFPS,
-			*EncoderFlags,
-			*VideoFilePath
-		);
-
-		UE_LOG(LogAudioVideoRecord, Log, TEXT("  FFmpeg cmd: %s"), *Cmd);
-
-		// popen opens a pipe — we write raw BGRA bytes into FFmpeg's stdin
-#if PLATFORM_WINDOWS
-		FFmpegVideoPipe = _popen(TCHAR_TO_ANSI(*Cmd), "wb");
-#else
-		FFmpegVideoPipe = popen(TCHAR_TO_ANSI(*Cmd), "w");
-#endif
-		if (!FFmpegVideoPipe)
-		{
-			UE_LOG(LogAudioVideoRecord, Error,
-				TEXT("SimpleRecorder: Failed to open FFmpeg pipe! Make sure ffmpeg.exe is on your PATH."));
-			bIsRecording = false;
-			return;
-		}
-	}
-
-	// ─── 2. Register back-buffer delegate (video frames) ────────────
 	if (FSlateApplication::IsInitialized())
 	{
 		BackBufferDelegateHandle =
@@ -200,7 +136,7 @@ void USimpleRecorder::StartRecording()
 			.AddUObject(this, &USimpleRecorder::OnBackBufferReady);
 	}
 
-	// ─── 3. Start audio submix recording ────────────────────────────
+	// ─── 2. Start audio submix recording ────────────────────────────
 	{
 		// Clear any leftover audio data
 		FScopeLock Lock(&AudioBufferCritSection);
@@ -302,32 +238,93 @@ void USimpleRecorder::StopRecording()
 	UE_LOG(LogAudioVideoRecord, Log, TEXT("SimpleRecorder: Recording stopped. All files saved."));
 }
 
+// =====================================================================
+// LaunchFFmpegVideoPipe — called once from first OnBackBufferReady
+// =====================================================================
+bool USimpleRecorder::LaunchFFmpegVideoPipe()
+{
+	FString FFmpeg = GetFFmpegExecutable();
+
+#if PLATFORM_MAC
+	FString EncoderFlags = FString::Printf(TEXT("-c:v h264_videotoolbox -b:v %s"), *VideoBitrate);
+#elif PLATFORM_WINDOWS
+	FString EncoderFlags = FString::Printf(TEXT("-c:v h264_nvenc -preset p5 -b:v %s"), *VideoBitrate);
+#else
+	FString EncoderFlags = FString::Printf(TEXT("-c:v libx264 -preset medium -b:v %s"), *VideoBitrate);
+#endif
+
+	// -movflags frag_keyframe+empty_moov writes fragmented MP4:
+	// each keyframe starts a new self-contained fragment, so the file
+	// is playable even if the process crashes mid-recording.
+	FString Cmd = FString::Printf(
+		TEXT("\"%s\" -y -f rawvideo -pix_fmt bgra -video_size %dx%d -framerate %d ")
+		TEXT("-i - %s -movflags frag_keyframe+empty_moov \"%s\""),
+		*FFmpeg,
+		CaptureWidth, CaptureHeight, CaptureFPS,
+		*EncoderFlags,
+		*VideoFilePath
+	);
+
+	UE_LOG(LogAudioVideoRecord, Log, TEXT("  Resolution: %dx%d @ %d FPS"), CaptureWidth, CaptureHeight, CaptureFPS);
+	UE_LOG(LogAudioVideoRecord, Log, TEXT("  FFmpeg cmd: %s"), *Cmd);
+
+#if PLATFORM_WINDOWS
+	FFmpegVideoPipe = _popen(TCHAR_TO_ANSI(*Cmd), "wb");
+#else
+	FFmpegVideoPipe = popen(TCHAR_TO_ANSI(*Cmd), "w");
+#endif
+	if (!FFmpegVideoPipe)
+	{
+		UE_LOG(LogAudioVideoRecord, Error,
+			TEXT("SimpleRecorder: Failed to open FFmpeg pipe!"));
+		return false;
+	}
+	return true;
+}
+
 // =====================================================================
 // OnBackBufferReady — called every presented frame on the RENDER thread
 // =====================================================================
 void USimpleRecorder::OnBackBufferReady(SWindow& SlateWindow, const FTextureRHIRef& BackBuffer)
 {
-	// Safety: if we already stopped, do nothing
+	if (!bIsRecording)
-	if (!bIsRecording || !FFmpegVideoPipe)
 	{
 		return;
 	}
 
-	// We're on the render thread here.
-	// Read the back-buffer pixels into a CPU-side array.
-
 	FRHICommandListImmediate& RHICmdList = FRHICommandListImmediate::Get();
-
-	// Determine actual back-buffer size (may differ from our target)
 	const FIntPoint BBSize = BackBuffer->GetSizeXY();
 
-	// We need a rect matching our capture resolution, clamped to back-buffer
+	// ─── First frame: read actual back-buffer size and start FFmpeg ──
+	if (!bFFmpegStarted)
+	{
+		// Use real back-buffer dimensions (not the DPI-scaled viewport size)
+		CaptureWidth  = (int32)BBSize.X & ~1;  // ensure even
+		CaptureHeight = (int32)BBSize.Y & ~1;
+
+		if (CaptureWidth <= 0 || CaptureHeight <= 0)
+		{
+			return; // back buffer not ready yet, try next frame
+		}
+
+		if (!LaunchFFmpegVideoPipe())
+		{
+			bIsRecording = false;
+			return;
+		}
+		bFFmpegStarted = true;
+	}
+
+	if (!FFmpegVideoPipe)
+	{
+		return;
+	}
+
+	// Read the full back-buffer at CaptureWidth x CaptureHeight
 	const int32 ReadW = FMath::Min(CaptureWidth,  (int32)BBSize.X);
 	const int32 ReadH = FMath::Min(CaptureHeight, (int32)BBSize.Y);
-
 	FIntRect ReadRect(0, 0, ReadW, ReadH);
 
-	// ReadSurfaceData puts pixels into a TArray<FColor> (BGRA, 8-bit per channel)
 	TArray<FColor> Pixels;
 	Pixels.SetNumUninitialized(ReadW * ReadH);
 
@@ -338,30 +335,7 @@ void USimpleRecorder::OnBackBufferReady(SWindow& SlateWindow, const FTextureRHIR
 		FReadSurfaceDataFlags(RCM_UNorm)
 	);
 
-	// If the back-buffer is smaller than our target, we still write the full
+	fwrite(Pixels.GetData(), sizeof(FColor), Pixels.Num(), FFmpegVideoPipe);
-	// frame size so FFmpeg doesn't choke. Pad with black if needed.
-	if (ReadW == CaptureWidth && ReadH == CaptureHeight)
-	{
-		// Fast path — dimensions match exactly
-		fwrite(Pixels.GetData(), sizeof(FColor), Pixels.Num(), FFmpegVideoPipe);
-	}
-	else
-	{
-		// Slow path — need to pad to CaptureWidth x CaptureHeight
-		// Allocate a black frame
-		TArray<FColor> PaddedFrame;
-		PaddedFrame.SetNumZeroed(CaptureWidth * CaptureHeight);
-
-		for (int32 Row = 0; Row < ReadH; ++Row)
-		{
-			FMemory::Memcpy(
-				&PaddedFrame[Row * CaptureWidth],
-				&Pixels[Row * ReadW],
-				ReadW * sizeof(FColor));
-		}
-
-		fwrite(PaddedFrame.GetData(), sizeof(FColor), PaddedFrame.Num(), FFmpegVideoPipe);
-	}
 }
 
 // =====================================================================

Source/AudioVideoRecord/SimpleRecorder.h

@@ -96,6 +96,9 @@ private:
 	/** Called every frame on the render thread when the back buffer is ready. */
 	void OnBackBufferReady(SWindow& SlateWindow, const FTextureRHIRef& BackBuffer);
 
+	/** Launches the FFmpeg video pipe with the actual back-buffer dimensions. */
+	bool LaunchFFmpegVideoPipe();
+
 	/** Writes the captured audio buffer to a .wav file. */
 	void SaveAudioToWav();
 
@@ -108,6 +111,7 @@ private:
 	// Video
 	FDelegateHandle            BackBufferDelegateHandle;
 	FILE*                      FFmpegVideoPipe = nullptr;
+	bool                       bFFmpegStarted = false;
 
 	// Audio — accumulated raw PCM data
 	TArray<float>              AudioBuffer;          // interleaved float samples

build-mac.sh

@@ -0,0 +1 @@
+"/Users/Shared/Epic Games/UE_5.6/Engine/Build/BatchFiles/Mac/Build.sh" AudioVideoRecordEditor Mac Development "/Users/johnjayasinghs/projects/axial/AudioVideoRecord/AudioVideoRecord.uproject"