Poor Stereo Separation with MP3 encoding

Audacity Help Forum GNU/Linux
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1

I’ve been using Audacity since a long time. Now, I’m using the 3.6.1 version inside computers with Ubuntu Studio 22.04.4 LTS (64 bit GNU/Linux), with Jack, Alsa, PulseAudio and partially PipeWire.
I’m not sure about when exactly this behaviour started but… I can notice a very poor stereo separation (too narrow stereo image compared with the original source) when I save any audio file with MP3 format.
After a while, thank an app called “Media Info”, I could know each MP3 audio file saved with Audacity, this year, has the following audio parameters (this is just a sample random song):

Audio
Format : MPEG Audio
Format version : Version 1
Format profile : Layer 3
Format settings : Joint stereo
Duration : 2 min 46 s
Bit rate mode : Constant
Bit rate : 320 kb/s
Channel(s) : 2 channels
Sampling rate : 44.1 kHz
Frame rate : 38.281 FPS (1152 SPF)
Compression mode : Lossy
Stream size : 6.34 MiB (100%)
Writing library : LAME3.100
Encoding settings : -m j -V 4 -q 3 -lowpass 20.5

The great difference with files saved before this year is about the last line:

Encoding settings : -m s -V 4 -q 3 -lowpass 20.5

SO… I guess the problem is with the characters “-m j”

If I’m right, How can I fix it and change those characters to get the full original stereo wide separation? ???

Or, If we can’t to change this… Is there a way to avoid that parameters was “read” when we play the songs with, let’s say, MPV Player (or whatever)? ???

BTW, When I use another editing software (whatever) to create MP3 files and I look for the same audio parameters with the same “Media Info” app, I can clearly see that last line is not there. In other words, it seems like Audacity is the only one software that add that parameter. Why? ???

2

Joint stereo uses L/R audio when applicable, it essentially means “auto”. Forced M/S audio is encoded with -m f.

3

You may need to export as WAV or FLAC and then use a 3rd party MP3 encoder. (I’m a Windows guy so I can’t recommend one.)

And here are the Lame Command Line Settings.

Those settings shouldn’t affect stereo separation. That particular processing is lossless/reversible (assuming it’s done right).

You might want to experiment with a left-only or right-only track. You’ll need to Split Stereo Track, mute one side, and export.

4

Thanks a lot!!!
But, your answer put a great doubt in my mind: If that parameter SHOULDN’T affect the stereo separation, Why I can hear a noticeable narrowing effect when I listen those files with MPV Player, or others sound playback apps? ???
Is there something related with the playback apps? ???
If it is that way, How can I fix it? ???

5

I think I found out the reason because I have this problem.
I’d have been experimented with all the resources I have and I think I discovered the problem starting point.
It isn’t audio Audacity files problem, it is something related with PipeWire and PulseAudio.
As Ubuntu Studio 22.04 doesn’t have a full PipeWire installation (it is just partially activated), there is a very weird dual existence between PipeWire and PulseAudio.
For some reason I can’t know (because I’m not a programmer), in some point of the process there is a weird combination between the Front Center channel (from hardware surround channels) with the both standard Front Left and Front Right channels (standard stereo computer output).
When I use an editing audio software with not surround audio output (like Audacity), I can hear the full stereo separation). But, when I use apps with surround sound capabilities, then I get the poor stereo separation.
I think some of the last Linux system upgrading changed something with the PipeWire sound server and this behaviour started to be this way.
Unfortunately, I cannot see some solution.
SO… It isn’t something related with Audacity.
The problem to me is I don’t have any clue about how to fix this. Sorry!
Thank you so much for your time!!!

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