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I would like to compress an mp3 file, and I see a lot of references when searching google, but it seems like by now someone must have found something easy and that is guaranteed to work.

Compressing a mp3 into a zip archive doesn't compress the file enough, but I am also concerned about too much loss of audio quality.

Does anyone have any experience in this? Could you share what you have found?

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5 Answers

up vote 18 down vote accepted

The archivers with the highest compression ratio would be KGB (which has been used to compress a 430 MB MS Office ISO to fit on a floppy disk) and Uharc (a high compression multimedia archiver), but they're not necessarily the fastest. The compression will be lossless.

If you want to reduce the size via the bitrate (and thus the quality), I recommend this program:

MP3 Quality Modifier makes it really easy to change the bitrate of your MP3 music collection so that the filesize can be dramatically reduced. With this advantage it's possible to put more music on your MP3-player or just to save some disk space. Even advanced tasks are possible: Downsampling, changing the used channels and so on. With the included presets it's simpler than ever before to manage all those settings. Best of all is that - unlike other software - the ID3 tags (title, album pictures etc.) will be completely retained without any effort!

Main features:

* Change MP3 quality with just a few clicks.
* Really easy and intuitive interface.
* Retain all ID3 tags with ease.
* Advanced options: detailed bitrate settings, sample frequency etc.
* Quality comparison: compare created files with original ones.
* Multilingual: English, French, German, Italian, Portuguese, Spanish.
* Portable: extremely small, just one executable, no installation.
* Free of charge!

screenshot

All programs are freeware and portable.

And if you want to learn more about audio ripping and MP3, here's a very comprehensive tutorial:

Radified Guide to Ripping CD audio & MP3 Encoding

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I don't believe it is possible to compress 430M to <1.40M. Source? –  Aaron Miller Jun 10 '13 at 20:02
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@AaronMiller Answered in 2009, user no longer exists... even links are broken now. Don't think he/she'll answer the source –  woliveirajr Jun 10 '13 at 20:14
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@woliveirajr A fair point which I hadn't noticed. Thanks! –  Aaron Miller Jun 10 '13 at 20:22
    
@AaronMiller I do know that it used the PAQ6 algorithm which is considered one of the very best to get the maximum compression ratio. The drawback is to get those ratios it can take GB of ram and potentially days to compress. A variant of PAQ consitantly wins the Calgary Challange with the current best compressing 3,141,622 of various types of files to 580,170 bytes of data (both payload and the program to decompress it). But that is still only a ratio of 18%, not the 0.2% the OP is claiming. –  Scott Chamberlain Mar 16 at 15:07
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As mp3s are already compressed - in much the same way that jpg images are compressed - simply adding it to a zip archive won't compress it any further as there is no redundant data to remove.

To reduce the size of an mp3 file you'll have to re-encode it at a lower bit rate using something like Media Monkey. This will result in a loss of quality, it you take the bit-rate too low. Media Monkey supports filtering and batch operations so you can select the files you want to re-encode and perform the operation in one go. This will also preserve any tagging you might have on the file. However, re-encoding an already lossy file will result in worse artefacts than you'd get by going back to the original source and encoding that at lower bit rate. You can demonstrate this effect by taking a jpg and re-save it several times reducing the quality each time.

Another thing to check is to ensure that any cover images are stored outside the mp3 file. Otherwise for an album of 12 tracks you'll have 12 copies of the same image.

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You may also use a different format such as AAC or WMA that can provide the same quality with a lower filesize. –  Badaro Dec 17 '09 at 13:20
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Thank you for explaining what I already stated in the question, but you really didn't answer my question. Especially not like Molly did. –  Geoffrey Chetwood Dec 17 '09 at 14:36
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@Rich B - sorry, I was just pointing out that simply adding an mp3 to a zip file won't compress the file any further. To do that you need to re-encode it, again as I pointed out. –  ChrisF Dec 17 '09 at 15:00
    
@ChrisF: Right. Which is what I had already said in my question. –  Geoffrey Chetwood Dec 17 '09 at 15:04
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Use lame from the command line (executable can be found here; there's also a tutorial on the command line options). Choose whatever settings you like best to reduce the size of your file; try using VBR (variable bitrate) and a bitrate of about 128 kbps. It should be more than enough to keep the audio quality to within normal limits. Listen to the mp3 and determine if it's ok.

Just try going as low as you can while still maintaining at least some audio quality (use 64 kbps and check the output). The sound volume of the mp3's will get lower and lower and you'll lose most of the richness of the sound.

Here's an example of how to use it:

lame -b 64 -h -V 6 input.mp3 output.mp3

This will encode it to 64 kbps (variable bitrate).

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"lame, which is used by most software for mp3 encoding." yeah, even Sony was stealing it, so it must be good! :) the-interweb.com/serendipity/index.php?/archives/… –  Molly7244 Dec 17 '09 at 13:39
    
As I said, used by most... –  alex Dec 17 '09 at 13:45
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SoundSlimmer can losslessly compress mp3 files by 15-20%. The software though not free can be obtained as a 14 days trial from here. I have tested this software personally and it works.

Another open source alternative which I found is packMP3. It can losslessly compress MP3 files by about 30%. It can be found here. The main program is a command line tool. GUI versions of the tool also exists and can also be found in the above link.

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Use MP3 Quality Modifier (freeware).

I managed to get some 11MB files down to 2MB. Minor quality loss due to me using 64-bit encoding but the choice to use higher is there as well so enjoy.

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