This script does the following:
1. Extracts audio from all .mp4 files using ffmpeg.
2. Takes the first second of the first extracted audio file as a noise sample using SoX.
3. Applies noise reduction and normalization filters to each audio file using SoX.
4. Re-insertes the cleaned audio back into the corresponding videos using ffmpeg.
5. Removes the original audio files and the noise profile file.
