This short video tutorial (5 minutes) shows how to prepare a video lecture for upload by normalising the audio level and applying fade-in/out to the start and end.
The Shotcut software (Windows, MacOS, Linux) can be downloaded from: shotcut.org
Summary of steps:
Open Shotcut.
Drag the original video file onto the Playlist.
Drag the video from the Playlist onto the Timeline.
Select the clip in the timeline and in the Filters panel add Normalize: Two Pass.
Click Analyze.
Set the desired target volume, e.g., -19 LUFS (Loudness Units relative to Full Scale).
In the Filters panel add: Fade In Audio, Fade Out Audio, Fade Out Video.