i need to increase the loudness of a movie

i am using vlc player on my laptop to watch movies and i watch movies at volume level 200%. my laptop has windows 10. i have some movies in which i am having problems in understanding the dialogue because its volume is low so i want to increase the loudness of the movie. i was using clever ffmpeg gui to do that by using the dynaudnorm algorithm or the loudnorm algorithm in order to increase the loudness. i did that for a couple of movies and there was no problem and then i noticed that in one movie the background music volume suddenly became low when the volume level is 200% and the problem didn’t happen if the volume level is 100%. https://www.youtube.com/watch?v=UNhswFHLCDw is a screen recording that i made of the issue. the same thing happened in another movie that i made louder by using the loudnorm algorithm

after that i made the first movie louder by using audacity 3.1.3. first i used the normalize effect by setting -0.1 for the compress to peak value and i ticked the remove dc offset checkbox. after that i used the compressor effect with compress based on peaks ticked and then i used the compressor effect again. i got the same problem like when i used the dynaudnorm algorithm in clever ffmpeg gui. if i used the compressor effect once and not twice then the problem didn’t happen in the first movie but i am worried that problems will happen in other movies

another way to increase the loudness by using audacity is by using the amplification effect with allow clipping not ticked. for the first movie i am only allowed to amplify by using 0.89db. that’s too low. i did some tests by adding gain. if i add +10db gain then the problem doesn’t happen, if i add +15db gain then the problem is not that noticeable and if i add +18db gain then the problem happens. i want to increase the gain by +10db but i am hearing that i am not supposed to do that because it exceeds the peak value

i want to be able to increase the loudness and be able to play the movie properly by using volume level 200% without having to worry about sudden drops in volume. i have been watching movies for more than 15 years by using vlc player at volume level 200% and there were no problems and the problems started when i am trying to make movies louder

So I can see your issue when I capture your audio from your video. I can see 1/2 second of clearly reduced audio in the second clip here:

Unfortunately, I am not able to reproduce your issue when trying to follow your normalize/compress instructions. Perhaps there is a setting difference in one of the parameters you did not specify.

Can you post a short clip along with clear instructions on exactly how to duplicate this issue in Audacity?

Normalize or Amplify first. That will “maximize” the volume linearly, based on the loudest part of the file.

Then try the Limiter effect with make-up gain and use hard limit or soft limit option. Since you have a “drastic” problem you might need to use the maximum -10dB setting. (With make-up gain this should boost the quiet parts by 10dB.)