diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9508ac193..b0fc3c808 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -20,16 +20,18 @@ include_directories(${CMAKE_SOURCE_DIR}/src/arm)
 include_directories(${CMAKE_SOURCE_DIR}/src/gba)
 include_directories(${CMAKE_SOURCE_DIR}/src)
 
+set(BUILD_PGO CACHE BOOL "Build with profiling-guided optimization")
+set(PGO_STAGE_2 CACHE BOOL "Rebuild for profiling-guided optimization after profiles have been generated")
 set(PGO_DIR "/tmp/gba-pgo/" CACHE PATH "Profiling-guided optimization profiles path")
-mark_as_advanced(PGO_DIR)
+mark_as_advanced(BUILD_PGO PGO_STAGE_2 PGO_DIR)
 set(PGO_PRE_FLAGS "-pg -fprofile-generate=${PGO_DIR}")
 set(PGO_POST_FLAGS "-fprofile-use=${PGO_DIR}")
 
-if(PGO_STAGE EQUAL 1)
+if(BUILD_PGO AND NOT PGO_STAGE_2)
 	set(CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE} ${PGO_PRE_FLAGS}")
 	set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${PGO_PRE_FLAGS}")
 	set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} ${PGO_PRE_FLAGS}")
-elseif(PGO_STAGE EQUAL 2)
+elseif(BUILD_PGO AND PGO_STAGE_2)
 	set(CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE} ${PGO_POST_FLAGS}")
 	set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${PGO_POST_FLAGS}")
 	set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} ${PGO_POST_FLAGS}")
diff --git a/src/gba/gba-rr.c b/src/gba/gba-rr.c
index f94a4da8e..3e8cd6b3d 100644
--- a/src/gba/gba-rr.c
+++ b/src/gba/gba-rr.c
@@ -41,7 +41,7 @@ void GBARRContextDestroy(struct GBA* gba) {
 	gba->rr = 0;
 }
 
-bool GBARRSetStream(struct GBARRContext* rr, struct VDir* stream) {
+bool GBARRInitStream(struct GBARRContext* rr, struct VDir* stream) {
 	if (rr->movieStream && !rr->movieStream->close(rr->movieStream)) {
 		return false;
 	}
@@ -54,13 +54,34 @@ bool GBARRSetStream(struct GBARRContext* rr, struct VDir* stream) {
 	rr->metadataFile = rr->streamDir->openFile(rr->streamDir, METADATA_FILENAME, O_CREAT | O_RDWR);
 	if (!_parseMetadata(rr, rr->metadataFile)) {
 		rr->metadataFile->close(rr->metadataFile);
-		rr->streamDir = 0;
 		rr->metadataFile = 0;
+		rr->maxStreamId = 1;
+	}
+	rr->streamId = 1;
+	rr->movieStream = 0;
+	return true;
+}
+
+bool GBARRReinitStream(struct GBARRContext* rr, enum GBARRInitFrom initFrom) {
+	if (!rr) {
 		return false;
 	}
-	rr->movieStream = 0;
+
+	if (rr->metadataFile) {
+		rr->metadataFile->truncate(rr->metadataFile, 0);
+	} else {
+		rr->metadataFile = rr->streamDir->openFile(rr->streamDir, METADATA_FILENAME, O_CREAT | O_TRUNC | O_RDWR);
+	}
+	_emitMagic(rr, rr->metadataFile);
+
+	rr->initFrom = initFrom;
+	rr->initFromOffset = rr->metadataFile->seek(rr->metadataFile, 0, SEEK_CUR);
+	_emitTag(rr, rr->metadataFile, TAG_INIT | initFrom);
+
 	rr->streamId = 1;
 	rr->maxStreamId = 1;
+	rr->maxStreamIdOffset = rr->metadataFile->seek(rr->metadataFile, 0, SEEK_CUR);
+	_emitTag(rr, rr->metadataFile, 1);
 	return true;
 }
 
@@ -315,9 +336,20 @@ enum GBARRTag _readTag(struct GBARRContext* rr, struct VFile* vf) {
 		vf->read(vf, &rr->lagFrames, sizeof(rr->lagFrames));
 		break;
 
+	case TAG_INIT_EX_NIHILO:
+		rr->initFrom = INIT_EX_NIHILO;
+		break;
+	case TAG_INIT_FROM_SAVEGAME:
+		rr->initFrom = INIT_FROM_SAVEGAME;
+		break;
+	case TAG_INIT_FROM_SAVESTATE:
+		rr->initFrom = INIT_FROM_SAVESTATE;
+	case TAG_INIT_FROM_BOTH:
+		rr->initFrom = INIT_FROM_BOTH;
+		break;
+
 	// To be spec'd
 	case TAG_RR_COUNT:
-	case TAG_INIT_TYPE:
 	case TAG_AUTHOR:
 	case TAG_COMMENT:
 		break;
@@ -362,9 +394,22 @@ bool _emitTag(struct GBARRContext* rr, struct VFile* vf, uint8_t tag) {
 }
 
 bool _parseMetadata(struct GBARRContext* rr, struct VFile* vf) {
+	if (!_verifyMagic(rr, vf)) {
+		return false;
+	}
 	while (_readTag(rr, vf) != TAG_EOF) {
-		if (rr->peekedTag == TAG_MAX_STREAM) {
+		switch (rr->peekedTag) {
+		case TAG_MAX_STREAM:
 			rr->maxStreamIdOffset = vf->seek(vf, 0, SEEK_CUR);
+			break;
+		case TAG_INIT_EX_NIHILO:
+		case TAG_INIT_FROM_SAVEGAME:
+		case TAG_INIT_FROM_SAVESTATE:
+		case TAG_INIT_FROM_BOTH:
+			rr->initFromOffset = vf->seek(vf, 0, SEEK_CUR);
+			break;
+		default:
+			break;
 		}
 	}
 	rr->maxStreamIdOffset = vf->seek(vf, 0, SEEK_SET);
diff --git a/src/gba/gba-rr.h b/src/gba/gba-rr.h
index 2817de569..0fe96caff 100644
--- a/src/gba/gba-rr.h
+++ b/src/gba/gba-rr.h
@@ -7,6 +7,13 @@ struct GBA;
 struct VDir;
 struct VFile;
 
+enum GBARRInitFrom {
+	INIT_EX_NIHILO = 0,
+	INIT_FROM_SAVEGAME = 1,
+	INIT_FROM_SAVESTATE = 2,
+	INIT_FROM_BOTH = 3,
+};
+
 enum GBARRTag {
 	// Playback tags
 	TAG_INVALID = 0x00,
@@ -25,7 +32,11 @@ enum GBARRTag {
 	TAG_FRAME_COUNT = 0x20,
 	TAG_LAG_COUNT = 0x21,
 	TAG_RR_COUNT = 0x22,
-	TAG_INIT_TYPE = 0x23,
+	TAG_INIT = 0x24,
+	TAG_INIT_EX_NIHILO = 0x24 | INIT_EX_NIHILO,
+	TAG_INIT_FROM_SAVEGAME = 0x24 | INIT_FROM_SAVEGAME,
+	TAG_INIT_FROM_SAVESTATE = 0x24 | INIT_FROM_SAVESTATE,
+	TAG_INIT_FROM_BOTH = 0x24 | INIT_FROM_BOTH,
 
 	// User metadata tags
 	TAG_AUTHOR = 0x30,
@@ -47,9 +58,13 @@ struct GBARRContext {
 	uint32_t frames;
 	uint32_t lagFrames;
 	uint32_t streamId;
+
 	uint32_t maxStreamId;
 	off_t maxStreamIdOffset;
 
+	enum GBARRInitFrom initFrom;
+	off_t initFromOffset;
+
 	// Streaming state
 	struct VDir* streamDir;
 	struct VFile* metadataFile;
@@ -63,7 +78,8 @@ struct GBARRContext {
 void GBARRContextCreate(struct GBA*);
 void GBARRContextDestroy(struct GBA*);
 
-bool GBARRSetStream(struct GBARRContext*, struct VDir*);
+bool GBARRInitStream(struct GBARRContext*, struct VDir*);
+bool GBARRReinitStream(struct GBARRContext*, enum GBARRInitFrom);
 bool GBARRLoadStream(struct GBARRContext*, uint32_t streamId);
 bool GBARRIncrementStream(struct GBARRContext*);
 bool GBARRSkipSegment(struct GBARRContext*);
diff --git a/src/platform/sdl/sdl-events.c b/src/platform/sdl/sdl-events.c
index 5fbbb88e7..d13e82493 100644
--- a/src/platform/sdl/sdl-events.c
+++ b/src/platform/sdl/sdl-events.c
@@ -127,7 +127,8 @@ static void _GBASDLHandleKeypress(struct GBAThread* context, struct GBASDLEvents
 						GBAThreadInterrupt(context);
 						GBARRContextCreate(context->gba);
 						if (!GBARRIsRecording(context->gba->rr)) {
-							GBARRSetStream(context->gba->rr, context->stateDir);
+							GBARRInitStream(context->gba->rr, context->stateDir);
+							GBARRReinitStream(context->gba->rr, INIT_FROM_SAVEGAME);
 							GBARRStopPlaying(context->gba->rr);
 							GBARRStartRecording(context->gba->rr);
 						}
@@ -139,7 +140,7 @@ static void _GBASDLHandleKeypress(struct GBAThread* context, struct GBASDLEvents
 						GBAThreadReset(context);
 						GBAThreadInterrupt(context);
 						GBARRContextCreate(context->gba);
-						GBARRSetStream(context->gba->rr, context->stateDir);
+						GBARRInitStream(context->gba->rr, context->stateDir);
 						GBARRStopRecording(context->gba->rr);
 						GBARRStartPlaying(context->gba->rr, event->keysym.mod & KMOD_SHIFT);
 						GBAThreadContinue(context);