can you convert music from mono to stereo?

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Level 1

25 points

can you convert music from mono to stereo?

Here's what i just did:

I noticed that a lot of my music in itunes had been imported into AIFF format, and in order to open up space on my hard drive, i decided to convert these files into MP3 format, by going into preferences>importing>import using, MP3 encoder, then converted the files (advanced>convert selection to MP3).
i naively neglected to check the bitrate setting, and ended up converting all of those files at a 32 kbps bitrate. so to rectify this, i changed the bitrate setting in preferences to 192 and then reselected all these files, and performed the convert to MP3 function again. by the time i next looked at the files, they had been converted to 96 kbps in mono. needless to say the sound quality is subpar.
how did they end up in a mono format?
i don't suppose there's a way to undo what i did, and restore these files to stereo?

thanks for your input.

PBG4, Mac OS X (10.3.8)

Posted on Dec 28, 2005 4:00 PM

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Answer 1

Dec 28, 2005 4:49 PM in response to Scott Fetzer

No. MP3 is a lossy encoding method, meaning that it permanently throws away data in the encoding process. The stereo information has already been lost. If you want MP3s with a bitrate of 192 kbps and preserved stereo information, then you need to go back to the original AIFF files or the original CDs and encode from there.

Double-check your importing settings. In the custom MP3 encoding settings, make sure that "Channels" is set to "Auto" and "Stereo Mode" is set to "Joint Stereo."

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Answer 2

Scott Fetzer Author

Level 1

25 points

Dec 28, 2005 10:06 PM in response to SpaceMonkey

now i'm importing, making sure i have the bitrate set at "higher quality" (192 kbps). after importing, the file info shows the channel as "stereo", as opposed to "joint stereo".
what is the difference?
also, when i have the importing setting configured as "higher quality" from the drop down menu, and not "custom", i would think that the settings as to the bitrate and channel information within the custom tab would be irrelevant. am i correct?

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Answer 3

Dec 28, 2005 10:28 PM in response to Scott Fetzer

You're right--I see now that the "Higher quality" option automatically selects normal stereo as opposed to joint stereo.

I guess if that is the default for that encoder at that bitrate then you should just leave it at that. Other MP3 encoders favor joint stereo for almost every bitrate.

Basically, whereas normal stereo always reserves half the bitrate for the Left and Right channels, joint stereo is a way to try to conserve bits that would ordinarily be wasted on one channel or the other at any given frame in the song. You can read more about it here. Like I said, other MP3 encoding programs prefer to use it at almost every bitrate because when intelligently implemented, it usually results at an increase in audio quality for any given bitrate. However, the iTunes encoder may implement joint stereo such a way that it isn't beneficial at 192 kbps--I don't know any of its inner workings. So best to just leave it at its default 192 kbps settings, I guess.

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Answer 4

Jan 1, 2006 8:41 AM in response to Scott Fetzer

Can't go back from mono. When you're importing to mp3, use the highest setting iTunes allows, and select the VBR option. It intelligently will compress each track to the best compression the track will merit. In my experience, this allows for reasonably decent compression without sacrificing much quality.

to do this though, you have to use the original AIFF files.

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