Realtime volume normalization

Question

I don't like having to adjust the volume when I'm steaming a movie, but it always seems like the dialogue is too low and the action scenes are too loud. So I'm looking for a solution.

Some background: I'm currently running arch and would like to first develop a solution that will work there. The end goal is to have a solution running on a raspberry pi. I'll split the audio from an HDMI input, run an analogue signal to the pi and send the output to a speaker.

Replacing /etc/asound.conf with the following is the only thing I've been able to find online.

pcm.!default {
    type asym
    playback.pcm "plug:ladcomp_compressor"
    capture.pcm "plug:dsnoop" 
}

pcm.ladcomp_compressor {
    type ladspa
    slave.pcm "ladcomp_limiter";
    path "/usr/lib/ladspa";
    plugins [
    {
        label dysonCompress
        input {
            #peak limit, release time, fast ratio, ratio
            controls [0 1 0.5 0.99]
        }
    }
    ]
}

pcm.ladcomp_limiter {
    type ladspa
    slave.pcm "plug:dmix"
    path "/usr/lib/ladspa";
    plugins [
    {
        label fastLookaheadLimiter
        input {
            #InputGain(Db) -20 -> +20 ; Limit (db) -20 -> 0 ; Release time (s) 0.01 -> 2
            controls [ 20 0 0.8  ]
        }
    }
    ]
}

(From a Reddit post https://www.reddit.com/r/linux/comments/of6bh/realtime_volume_normalization/) But I'm not sure it is working. Can someone explain how this config is working or share better ideas.

Answer 1

I'm not sure that the config you have there is really aiming to solve your problem, even though you aren't the only person complaining about the legibility of dialogue.

This config, though, is for averaging out the volume of generally separate sound sources, such as switching between songs, or when louder adverts start. It runs the sound firstly through a limiter to keep the volume within set bounds, then a compressor to average out the sound, leveling off the peaks and raising up other bits.

Whether this is a good idea on audio sources that will already have been mastered to within an inch of their lives is probably not for me to say..

Admittedly this isn't much help for you, but the only suggestions I can think of are:

1. firstly playing around with eq settings in the video player you choose, as dialogue is mostly limited to a smallish frequency range. You may be able to find advice somewhere online.
2. If you can access surround sound from a DVD etc. you could adjust the centre front speaker volume, as often this is where the dialogue is mixed to. Then there should be a way to mix down to stereo for audio output.

Unhelpfully, I don't know how to do either of those, but this may give you a few pointers on possible ways of dealing with things.