Ghost of the mp3

[crackinkid]

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I was trying to use a technique Ryan Maguire used to create what he called the ghost of the mp3:
https://pdfs.semanticscholar.org/5997/b ... 876cad.pdf (https://pdfs.semanticscholar.org/5997/b358206f894f3a1571e1c4a8af68f9876cad.pdf)

Basically you can take a loseless audio file and subtract (phase invert) the compressed file (mp3) render that to a new file and your left with the frequencies that usually get lost during compression.
There are two methods he used to achieve this:

1.Take a wav and a mp3 (same file), phase invert the mp3 and render to a new file.
2. And "zero the corresponding bins in the original uncompressed file where the difference is null or near-null, i.e.- using the MP3 as a mask on the original file".

The First method is very easy to recreate with any daw, but I want to try the second one for different sonical results. But I have absolutely no idea how to achieve this and almost no coding experience at all (except visual programming).
He mentioned python and some libs for that, but sadly I have no details of that process
Anyone got an idea?

[antto]

you should watch out for delay
this probably strongly depends on the mp3 encoder, but i have noticed that many times the stuff i encode to mp3 get some delay added before the start
so if you expect them to "null-out" with the input - they won't even if they were sonically perfect

as for the second method, it smells like instructions for FFT (i haven't read the pdf)

[andrewbrewer]

LoHI by Goodhertz seems like it can do things like this. It does more than mp3 imitations, I’m pretty sure it has a setting to only pass on the residue of its pseudo-mp3 imitation. Whatever it’s doing I can tell you it can easily sound ghostly on some settings

[crackinkid]

@antto you're right they have to perfectly align. but that's no so hard to accomplish, but the results are not as interesting as i hoped.
but i think the second method might produce a more echoy ghostly sound.
@andrewbrewer
Do you mean Lossy? Thank you for the hint. I'm gonna try that, I've also noticed that specops by unfiltered audio seems to have a mp3fiy setting.

But I'm still really interested in the 2nd process, and yes it's some kind of fft method but with coding in python :I

Edit: O wow, Lossy has a preset called "ghost in the mp3" I think it's not exactly the same as the fft method but sounds kinda similar.

[andrewbrewer]

@andrewbrewer
Do you mean Lossy?

Oops! Yes Lossy! SpecOps is also great and just flat out cool and over the top with features.