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Topic: Making MP3's sound more stereo (Read 2856 times)
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## Re: Making MP3's sound more stereo

##### Reply #25 – 2024-07-31 08:54:58
Use special VST effects such as MSED Voxengo on foobar2000
Read the thread – the OP was hoping for a way to manipulate the original MP3 (similar to setting gain).  He's already been told it can't be done, and either has to use facilities in the player or has to process the original audio and re-encode.
It's your privilege to disagree, but that doesn't make you right and me wrong.

## Re: Making MP3's sound more stereo

##### Reply #26 – 2024-07-31 12:43:07
Frequency domain. It's mathematically equivalent to time domain if you're doing the same mid/side transform on all frequencies, but MP3 allows switching between mid/side and intensity stereo.

Not sure If I worded my doubt clear enough.

I mean given an MP3 decoder, seeing a M/S encoded frame, which one of these will do:

- decode the MID to time domain, decode the SIDE to time domain, then calculate samples as L=MID+SIDE, R=MID-SIDE
- calculate frequency bins as L=MID+SIDE, R=MID-SIDE, decode L to time domain, decode R to time domain.

You might be right that the calculation might give the same results, but of course that would mean that the calculation in the frequency domain has to be done with Real numbers, (So taking into account the angle).

## Re: Making MP3's sound more stereo

##### Reply #27 – 2024-07-31 15:48:18
- There is a foobar component called foo_dsp_midside which is able convert stereo to mid/side. It's interesting to hear, but otherwise not very useful.
- Another foobar component called Channel Mixer (foo_channel_mixer) can expand the stereo image width. I presume mid/side is used for this effect.

I'm sure there are more components which can expand the stereo image, but Channel Mixer is the one i already had installed.

## Re: Making MP3's sound more stereo

##### Reply #28 – 2024-08-01 23:42:18
- decode the MID to time domain, decode the SIDE to time domain, then calculate samples as L=MID+SIDE, R=MID-SIDE
- calculate frequency bins as L=MID+SIDE, R=MID-SIDE, decode L to time domain, decode R to time domain.
The second one.

You might be right that the calculation might give the same results, but of course that would mean that the calculation in the frequency domain has to be done with Real numbers, (So taking into account the angle).
Real numbers don't have an angle. Are you thinking of complex numbers? MP3 doesn't use complex numbers in the frequency domain.

## Re: Making MP3's sound more stereo

##### Reply #29 – 2024-08-02 04:11:31
You might be right that the calculation might give the same results, but of course that would mean that the calculation in the frequency domain has to be done with Real numbers, (So taking into account the angle).
Real numbers don't have an angle. Are you thinking of complex numbers? MP3 doesn't use complex numbers in the frequency domain.
Actually, most lossy formats including MP3 and AAC use MDCT (modified discrete cosine transform) in which real-valued frequency-domain data is returned and unlike magnitude FFT (which is hypotenuse of re(x) and im(x) values of complex spectrum), the MDCT can have negative values, instead of good old FFT (which returns complex values)