Fixed more issues with the synchronous option

Signed-off-by: Andrew Welch <andrew@nystudio107.com>

Author: khalwat

src/services/Transcode.php

@@ -425,7 +425,7 @@ public function getAudioUrl($filePath, $audioOptions): string
                 $result = Craft::getAlias($url).$destAudioFile;
             } else {
                 // Kick off the transcoding
-                $this->executeShellCommand($ffmpegCmd);
+                $pid = $this->executeShellCommand($ffmpegCmd);
 
                 if ($synchronous) {
                     Craft::info($ffmpegCmd, __METHOD__);