More "Media Info -application" on the source media might help. Then let people know the details of your project settings (screenshots), and what render template you are attempting to use. There should be no reason to use uncompressed for a wedding video.
The way I would handle that type of change is to use FFMPEG and extract the audio from source media. Then make changes you want to the audio. Then re-mux the audio track back to the video source, this will copy the video with no re-compression.