Automatically adjust the volume based on content?

Adjusting sound level with a LADSPA plugin

To obtain a fairly normalized sound output level independent of the input level we may use a LADSPA-plugin to filter the sound output through PulseAudio.

• see also: How can I apply a LADSPA plugin to a PulseAudio stream?

As a minimum, we need a compressor plugin such as the dysonCompressor from the swh-plugins which need to be installed if not yet present.

After having found out the name of our default sink with

pacmd list-sinks

and the exact name of the plugin as it is stored in /usr/lib/ladspa/ (with my system here dyson_compress_1403) we can issue the following command

pacmd load-module module-ladspa-sink sink_name=ladspa_sink master=<alsa_output> plugin=dyson_compress_1403 label=dysonCompress control=0,1,0.5,0.99

Replace <alsa_output> with the exact name of the output sink (in my system this was alsa_output.pci-0000_00_14.2.analog-stereo).

The compressed output can now be heard on the newly created output sink ladspa_sink accessible from the Sound Settings menu.

Control settings for the compressor plugin are as follows: peak limit, release time, fast ratio, ratio. See in the plugin documentation for more details, defaults and minimal resp maximal values for these controls.

To avoid clipping of playback we may also combine this plugin with a limiter after compression. We may use the fast_lookahead_limiter for this with the master sink being now our just created lasdpa_sink from above:

pacmd load-module module-ladspa-sink sink_name=ladspa_normalized master=ladspa_sink plugin=fast_lookahead_limiter_1913 label=fastLookaheadLimiter control=10,0,0.8

^{Source: settings above were adapted to pulseaudio from brien's blog on miscfits}

Takkat's solution is good, but here's a variation which is simpler and permanent.

1. apt-get install swh-plugins

2. Cut and paste the following into a file called ~/.config/pulse/default.pa:

   .nofail
   .include /etc/pulse/default.pa
   load-module module-ladspa-sink  sink_name=ladspa_sink  plugin=dyson_compress_1403  label=dysonCompress  control=0,1,0.5,0.99
   load-module module-ladspa-sink  sink_name=ladspa_normalized  master=ladspa_sink  plugin=fast_lookahead_limiter_1913  label=fastLookaheadLimiter  control=10,0,0.8
   set-default-sink ladspa_normalized
   

3. Run pulseaudio -k or log out and back in again

Normalization will automatically be turned on for all subsequent logins.

Volume normalization is present in SMPlayer. Goto software center and download this awesome player, then enable volume normalization under audio options :)

Earlier I was also having audio normalization issues while playing movies on my VLC media player but few searches over Internet I was able to find a perfect solution for this and I have shared it below so that you can also benefit from it....

Audio Normalization VLC Fix / Audio Out of Sync VLC Fix

Along with an alternative, I have some comments to the solutions above that suggest using the dysoncompressor.

From the manual:

 2.37  Dyson compressor (dysonCompress, 1403)
Peak limit (dB)
Controls the desired limit of the output signal in dB's.
Release time (s)
Controls the time taken for the compressor to relax its gain control over the input signal.
Fast compression ratio
I have no clear idea what this controls.
Compression ratio
I have no clear idea what this controls. 

http://plugin.org.uk/ladspa-swh/docs/ladspa-swh.html#tth_sEc1.1

The author of the package doesn't know what the last two values control. So how could you all say what you should input as the last two values?

The plugin itself suggests control=0,0.25,0.5,0.5

$ analyseplugin /usr/lib/ladspa/dyson_compress_1403.so

Plugin Name: "Dyson compressor"
Plugin Label: "dysonCompress"
Plugin Unique ID: 1403
Maker: "Steve Harris <[email protected]>"
Copyright: "GPL"
Must Run Real-Time: No
Has activate() Function: Yes
Has deactivate() Function: No
Has run_adding() Function: Yes
Environment: Normal or Hard Real-Time
Ports:  "Peak limit (dB)" input, control, -30 to 0, default 0
    "Release time (s)" input, control, 0 to 1, default 0.25
    "Fast compression ratio" input, control, 0 to 1, default 0.5
    "Compression ratio" input, control, 0 to 1, default 0.5
    "Input" input, audio
    "Output" output, audio

I would even suggest that you try one of the other compressors, that seem better documented, like sc4.

load-module module-ladspa-sink  sink_name=ladspa_sink  plugin=sc4_1882 label=sc4  control=0,101.125,401,0,1,3.25,0