The Ghost in the MP3

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The Ghost in the MP3

Postby Sunbeam » Fri Jan 08, 2016 5:31 am

As most folks are aware, the MP3 music format uses "lossy compression" to achieve small file sizes, and lower bit-rates, useful for portable players or streaming.

This means that, using a "perceptual coding" technique, parts of the music signal are discarded.

Have you ever wondered what the discarded parts might sound like? I have, and so has composer Ryan Maguire, who is releasing compositions using what he calls "The Ghost in the MP3".

I discovered this (and was fascinated by the sounds I heard) listening to Spark, on CBC Radio on my way to work Wednesday afternoon. Here's a link to the Spark segment podcast (only 6:42, well worth the listen) and a bit more background:
http://www.cbc.ca/radio/spark/best-of-s ... -1.3378656

Here's a link to Ryan Maguire's web-page:
http://theghostinthemp3.com/theghostinthemp3.html

He has (uncompressed) music files you can listen to (free) on bandcamp:
https://rpm7.bandcamp.com/album/the-ghost-in-the-mp3

And here's a link to his paper which gives a deeper background on the whole subject:
http://ryanmaguiremusic.com/media_files ... stICMC.pdf

Fascinating stuff. I know I'm a weird techie, but it's still fascinating stuff.
David, I think Igor will like this :) Definitely spend the 7 minutes to check out the CBC Spark segment, then check out the rest if it grabs your attention .
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Re: The Ghost in the MP3

Postby Sunbeam » Sun Jan 31, 2016 2:03 am

When I get a chance, I just *have* to try an experiment with this.

The basic procedure is:

1-Take a .WAV file of a song of interest.

2-Convert it to mp3.

3-Load the original .WAV version into an audio editor, like Audacity.

4-Load in the .mp3 converted version of the file as another stereo track.

5-Make sure the two tracks are in sync.

6-Create a "Difference" file, i.e, subtract the mp3 content from the WAV content.

The resulting file contains only the audio that was "thrown away" in the mp3 conversion process. From the examples I've heard, these mp3 'discard' files can sound quite ethereal and stunning. These are the sounds you don't hear when you play an mp3.

Maybe the appreciation of this requires the perceptual enhancements championed by Timothy Leary. Maybe it's a new art-form created as a by-product of technology. Maybe it's a new DJ tool. Just thinking...and listening... and thinking...
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Re: The Ghost in the MP3

Postby Sunbeam » Sat Nov 04, 2017 11:34 pm

bump
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Re: The Ghost in the MP3

Postby Krynoid » Sun Nov 05, 2017 6:09 pm

I gave it a go with a MP3 and a FLAC (just to prove it was lossless) and it worked!

The FLAC produced complete silence and the 320k MP3 produced quite a lot.

My first go was with an electronic song. I plan to try it with an acoustic song at another time.

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