diff --git a/transcoder/handler.go b/transcoder/handler.go
--- a/transcoder/handler.go
+++ b/transcoder/handler.go
@@ -37,6 +37,14 @@ func NewHandler(c *Config) *Handler {
 }
 
 func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Access-Control-Allow-Origin", "*")
+	w.Header().Set("Access-Control-Allow-Methods", "GET, HEAD, OPTIONS")
+	w.Header().Set("Access-Control-Allow-Headers", "Range, Content-Type")
+	if r.Method == http.MethodOptions {
+		w.WriteHeader(http.StatusNoContent)
+		return
+	}
+
 	// Check version if monitoring is enabled
 	if h.c.VersionMonitor && !h.versionOk(w, r) {
 		return
@@ -55,15 +63,15 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}
 
 	// Serve actual file from manager
-	if len(parts) < 3 {
+	if len(parts) < 5 || parts[0] != "vod" {
 		log.Println("Invalid URL", url)
 		w.WriteHeader(http.StatusBadRequest)
 		return
 	}
 
 	// Get streamid and chunk
-	streamid := parts[0]
-	path := "/" + strings.Join(parts[1:len(parts)-1], "/")
+	streamid := parts[1]
+	path := "/" + strings.Join(parts[2:len(parts)-1], "/")
 	chunk := parts[len(parts)-1]
 
 	// Check if POST request to create temp file
@@ -133,10 +141,7 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}
 
 	// Get existing manager or create new one
-	manager := h.getManager(path, streamid)
-	if manager == nil {
-		manager = h.createManager(path, streamid)
-	}
+	manager := h.getOrCreateManager(path, streamid)
 
 	// Failed to create manager
 	if manager == nil {
@@ -166,33 +172,29 @@ func (h *Handler) versionOk(w http.ResponseWriter, r *http.Request) bool {
 	return true
 }
 
-func (h *Handler) getManager(path string, streamid string) *Manager {
-	h.mutex.RLock()
-	defer h.mutex.RUnlock()
-
-	m := h.managers[streamid]
-	if m == nil || m.path != path {
-		return nil
-	}
-	return m
-}
-
-func (h *Handler) createManager(path string, streamid string) *Manager {
+func (h *Handler) getOrCreateManager(path string, streamid string) *Manager {
+	// Lookup and creation must be atomic. Master, variant, and segment requests
+	// commonly arrive together; concurrent creators share a tempDir, and the
+	// losing manager's Destroy would delete the winner's active segment files.
+	h.mutex.Lock()
+	defer h.mutex.Unlock()
+
+	old := h.managers[streamid]
+	if old != nil && old.path == path {
+		return old
+	}
+
 	manager, err := NewManager(h.c, path, streamid, h.close)
 	if err != nil {
 		log.Println("Error creating manager", err)
 		freeIfTemp(path)
 		return nil
 	}
 
-	h.mutex.Lock()
-	defer h.mutex.Unlock()
-
-	old := h.managers[streamid]
 	if old != nil {
 		old.Destroy()
 	}
 
 	h.managers[streamid] = manager
 	return manager
 }
diff --git a/transcoder/stream.go b/transcoder/stream.go
--- a/transcoder/stream.go
+++ b/transcoder/stream.go
@@ -370,8 +370,12 @@ func (s *Stream) transcodeArgs(startAt float64, isHls bool) []string {
 	// Check whether hwaccel should be used
 	if s.c.VAAPI {
 		CV = ENCODER_VAAPI
-		extra := "-hwaccel vaapi -hwaccel_device /dev/dri/renderD128 -hwaccel_output_format vaapi -init_hw_device vaapi=memories:/dev/dri/renderD128 -filter_hw_device memories"
+		extra := "-init_hw_device vaapi=memories:/dev/dri/renderD128 -filter_hw_device memories"
 		args = append(args, strings.Split(extra, " ")...)
+		if s.m.probe.CodecName == CODEC_H264 {
+			extra = "-hwaccel vaapi -hwaccel_device /dev/dri/renderD128 -hwaccel_output_format vaapi"
+			args = append(args, strings.Split(extra, " ")...)
+		}
 	} else if s.c.NVENC {
 		CV = ENCODER_NVENC
 		extra := "-hwaccel cuda"
@@ -397,7 +401,11 @@ func (s *Stream) transcodeArgs(startAt float64, isHls bool) []string {
 	scalerArgs = append(scalerArgs, "force_original_aspect_ratio=decrease")
 
 	if CV == ENCODER_VAAPI {
-		format = "format=nv12|vaapi,hwupload"
+		if s.m.probe.CodecName == CODEC_H264 {
+			format = "format=nv12|vaapi,hwupload"
+		} else {
+			format = "format=nv12,hwupload"
+		}
 		scaler = "scale_vaapi"
 		scalerArgs = append(scalerArgs, "format=nv12")
 	} else if CV == ENCODER_NVENC {