diff --git a/lib/BigBlueButton/Presentation.php b/lib/BigBlueButton/Presentation.php
index b473def..1efaaa0 100644
--- a/lib/BigBlueButton/Presentation.php
+++ b/lib/BigBlueButton/Presentation.php
@@ -2,37 +2,49 @@
 
 namespace OCA\BigBlueButton\BigBlueButton;
 
+use OCP\Files\IRootFolder;
+use OCP\Files\File;
 use OCP\Files\Storage\IStorage;
 
-class Presentation {
+class Presentation
+{
 	private $url;
 
-	private $filename;
+	/** @var File*/
+	private $file;
 
-	private $path;
+	/** @var IRootFolder */
+	private $userFolder;
 
 	/** @var IStorage */
 	private $storage;
 
-	public function __construct(string $path, IStorage $storage) {
-		$this->storage = $storage;
-		$this->path = preg_replace('/^\//', '', $path);
-		$this->filename = preg_replace('/[^\x20-\x7E]+/','#', $path);
+	public function __construct(string $path, string $userID, IRootFolder $iRootFolder)
+	{
+		$userFolder = $iRootFolder->getUserFolder($userID);
+		$this->file = $userFolder->get($path);
+		$this->storage = $this->file->getStorage();
 	}
 
-	public function generateUrl(): string {
-		return $this->storage->getDirectDownload($this->path);
+	public function generateUrl(): string
+	{
+		$filePath = $this->file->getInternalPath();
+		[$url] = $this->storage->getDirectDownload($filePath);
+		return $url;
 	}
 
-	public function getUrl(): string {
+	public function getUrl(): string
+	{
 		return $this->url;
 	}
 
-	public function getFilename(): string {
-		return $this->filename;
+	public function getFilename(): string
+	{
+		return $this->file->getName();
 	}
 
-	public function isValid(): bool {
-		return !empty($this->filename);
+	public function isValid(): bool
+	{
+		return !empty($this->file->getContent());
 	}
 }
diff --git a/lib/Controller/JoinController.php b/lib/Controller/JoinController.php
index 4e5387d..6115e29 100644
--- a/lib/Controller/JoinController.php
+++ b/lib/Controller/JoinController.php
@@ -14,7 +14,7 @@ use OCP\AppFramework\Controller;
 use OCP\AppFramework\Http\RedirectResponse;
 use OCP\AppFramework\Http\TemplateResponse;
 use OCP\BackgroundJob\IJobList;
-use OCP\Files\Storage\IStorage;
+use OCP\Files\IRootFolder;
 use OCP\IRequest;
 use OCP\IURLGenerator;
 use OCP\IUserSession;
@@ -45,8 +45,8 @@ class JoinController extends Controller
 	/** @var IJobList */
 	private $jobList;
 
-	/** @var IStorage */
-	private $storage;
+	/** @var IRootFolder */
+	private $iRootFolder;
 
 	public function __construct(
 		string $appName,
@@ -57,7 +57,7 @@ class JoinController extends Controller
 		API $api,
 		Permission $permission,
 		IJobList $jobList,
-		IStorage $storage
+		IRootFolder $iRootFolder
 	) {
 		parent::__construct($appName, $request);
 
@@ -67,7 +67,7 @@ class JoinController extends Controller
 		$this->api = $api;
 		$this->permission = $permission;
 		$this->jobList = $jobList;
-		$this->storage = $storage;
+		$this->iRootFolder = $iRootFolder;
 	}
 
 	public function setToken(string $token): void
@@ -117,13 +117,12 @@ class JoinController extends Controller
 				throw new NoPermissionException();
 			}
 
-			if ($this->permission->isAdmin($room, $userId)) {
-				$presentation = new Presentation($filename, $this->storage);
-			}
-
-			if (!$room->running && $presentation === null) {
-				$presentation = new Presentation($room->presentationPath, $this->storage);
+			if ($this->permission->isAdmin($room, $userId) && !empty($filename)) {
+				$presentation = new Presentation($filename, $userId, $this->iRootFolder);
+			} else if (!$room->running && !empty($room->presentationPath)) {
+				$presentation = new Presentation($room->presentationPath, $room->presentationUserId, $this->iRootFolder);
 			}
+			
 		} elseif ($room->access === Room::ACCESS_INTERNAL || $room->access === Room::ACCESS_INTERNAL_RESTRICTED) {
 			return new RedirectResponse($this->getLoginUrl());
 		} elseif (empty($displayname) || strlen($displayname) < 3 || ($room->access === Room::ACCESS_PASSWORD && $password !== $room->password)) {