How can I merge webm and wav file without using FFMpeg lib in PHP shared hosting?

I want to merge webm video with a WAV audio file. Is there any way to do that in shared php hosting?

My final target is:

I have two files (Webm & WAV). I want to upload a video into youtube programmatically. But my audio & video file are different. I have only shared PHP server so I can't use FFMpeg or node.js to merge. So Is there any way to do this?

Please advice me.