Audio equalizer

[ion@office ~]$ garuda-inxi
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What audio equalizer can I use with mpg123?

It looks like it has a built-in equalizer, or do you mean something different?

fish❯ mpg123
You made some mistake in program usage... let me briefly remind you:

High Performance MPEG 1.0/2.0/2.5 Audio Player for Layers 1, 2 and 3
	version 1.31.3; written and copyright by Michael Hipp and others
	free software (LGPL) without any warranty but with best wishes

usage: mpg123 [option(s)] [file(s) | URL(s) | -]
supported options [defaults in brackets]:
   -v    increase verbosity level       -q    quiet (don't print title)
   -t    testmode (no output)           -s    write to stdout
   -w f  write output as WAV file
   -k n  skip first n frames [0]        -n n  decode only n frames [all]
   -c    check range violations         -y    DISABLE resync on errors
   -b n  output buffer: n Kbytes [0]    -f n  change scalefactor [32768]
   -r n  set/force samplerate [auto]
   -o m  select output module           -a d  set audio device
   -2    downsample 1:2 (22 kHz)        -4    downsample 1:4 (11 kHz)
   -d n  play every n'th frame only     -h n  play every frame n times
   -0    decode channel 0 (left) only   -1    decode channel 1 (right) only
   -m    mix both channels (mono)       -p p  use HTTP proxy p [$HTTP_PROXY]
   -@ f  read filenames/URLs from f     -T get realtime priority
   -z    shuffle play (with wildcards)  -Z    random play
   -u a  HTTP authentication string     -E f  Equalizer, data from file
   -C    enable control keys            --no-gapless  not skip junk/padding in mp3s
   -?    this help                      --version  print name + version
See the manpage mpg123(1) or call mpg123 with --longhelp for more parameters and information.
man mpg123
       -E file, --equalizer
              Enables  equalization,  taken from file.  The file needs to contain 32 lines of data, additional comment lines may be prefixed with #.  Each data line consists of two float‐
              ing-point entries, separated by whitespace.  They specify the multipliers for left and right channel of a certain frequency band, respectively.  The first  line  corresponds
              to  the  lowest, the 32nd to the highest frequency band.  Note that you can control the equalizer interactively with the generic control interface.  Also note that these are
              the 32 bands of the MPEG codec, not spaced like you would see for a usual graphic equalizer. The upside is that there is zero computational cost in addition to decoding. The
              downside is that you roughly have bass in band 0, (upper) mids in band 1, treble in all others.

It's not something you can tweak in real time, and has limitations as detailed above.

Other than that, you may use any "system level" equalizer, like EasyEffects or JamesDSP.
Mind their "autostart" feature, there has been reports of that causing problems (silent output, videos not starting until muting/unmuting, that sort of things).

There may be other options I'm not aware of.


Thank you for your response. I have tried both EasyEffects and JamesDSP without success. With both mgp123 and my default mp3 player mocp. The problem being that adjustment has to be done in real time. I have never understood the ever-changing and complicated methods of audio reproduction once it left the electronic/physical/analog world. Pipewire, ALSA, JACK, etc. Yes, I can buy a multiband hardware equalizer. Expensive, and one more large box to take up desk space.

Eh I feel you, I was born when analog electronics was a modern thing... my first amplifier was made of glass valves, and believe it or not, was built by my mom in her days. It still works by the way.
And it saturates without clipping, only even harmonics if I crank it up too much.
An analog hardware eq will likely give better sound quality without latency, whether it's worth it depends what you're listening to. In my opinion, it's wasted on the average mp3.
Still I think a software one should do, can you better explain "without success"?
Now that I think of it, perhaps mpg123 and the like use ALSA directly and bypass them.
I'll have a look at that later, now I'm too drunk.

So, I just tried mpg123 with EasyEffects and it does work, but gives me crackling sound while adjusting it (may be my laptop is just too slow). If I recall correctly, I also had to install a bunch of optional dependencies for EasyEffects (it was some time ago).

alsaequal (or rather, alsamixer) is giving me headache to set up, I'll get back.
(it doesn't find but it's there) <-- solved with export LADSPA_PATH=/usr/lib/ladspa
Now if I can get the .asoundrc right...

edit: @ionmich
Apparently the problem was not with the .asoundrc (the advised one works).
I was using mpg123 -a equal FILE.mp3, thinking it would either work or complain, but the equalizer was not affecting it. Looks like it falls back when it's not valid: -a null indeed does what expected, but -a crap plays audio to the sound card.
When I tried explicitly requesting ALSA output with mpg123 -o alsa -a equal FILE.mp3 I got this:

High Performance MPEG 1.0/2.0/2.5 Audio Player for Layers 1, 2 and 3
	version 1.31.3; written and copyright by Michael Hipp and others
	free software (LGPL) without any warranty but with best wishes
ALSA lib dlmisc.c:337:(snd_dlobj_cache_get0) Cannot open shared library (/usr/lib/alsa-lib/ undefined symbol: snd_config_iterator_next)
[src/libout123/modules/alsa.c:open_alsa():181] error: cannot open device equal
[src/libout123/libout123.c:check_output_module():947] error: Module 'alsa' device open failed.
[src/libout123/libout123.c:out123_open():439] error: Found no driver out of [alsa] working with device equal.
main: [src/mpg123.c:check_fatal_output():334] error: out123 error 3: failure loading driver module

Lame work-around: mpg123 --au - FILE.mp3 |aplay -Dequal.
Also, in case of more than one output device (in my case, HDMI output counts as a separate one), the default slave.pcm "plughw:0,0" can be changed to slave.pcm "default" so that audio goes to whatever the default currently is instead of the first device (internal laptop speakers in my case).

As for EasyEffects, looks like it requires this for the equalizer:

Optional Deps:  lsp-plugins-lv2: equalizer, compressor, delay, loudness

and then has to be added to the pipeline, under "𝅳𝅗𝅥𝅗𝅥𝅴Effects", "Add Effect".

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I get the best audio effects results with Pipewire, Wireplumber, and JamesDSP, however JamesDSP does distort if run minimized to the tray.


Thanks for all your efforts to solve my problem. Here is the crux of the matter. I have software (mocp) that does exactly what I want. It plays all my stored music very simply. Yes I use mpg123, an excellent application for online streaming, where I have no control over content. But mocp is ancient software and does not come with a realtime equalizer. I used a variety of simple equalizers (not 30+ bands, more like 8) . Many years ago they worked. Since recent enhancements I have not had any success. They are now much more complicated with all sorts of "effects". Just fine for a recording studio. Everything I have tried needed installing more software, that failed, and more new software that also failed. I have made a decision. I will buy a simple, physical, automotive equalizer and end months of frustration.

Thanks again.

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