Tools for converting left channel only of MP3 to mono

[Dinosaur Punk]

I've got a bunch of instructional recordings. For example, "Building Walking Basslines" These are mixed with bass on the right and the backing track on the left. However, my playback system is an iPod + Monitor speakers - there's no easy way to adjust the balance.

Anyone know of an easy way to create mono MP3's from stereo. I have Goldwave and Audacity on my PC, and Audacity, Garage Band, and Sonic Pro on my Mac.

I tried Audacity but couldn't seem to delete a single track.

I'd like not to have to re-encode anything. Even better would be batch conversion. Seems to me there ought to be a way to edit the MP3 metadata to create a mono file without re-encoding.

The purpose of this is to have only the backing track, without bass playing.

I also bought some hardware jacks to do this, but they won't get here for about a week.

[Alvaro Martín Gómez A.]

Originally Posted by Dinosaur Punk

I tried Audacity but couldn't seem to delete a single track.

I haven't tried Audacity, but I think that any audio editor should allow you to perform such a simple task like selecting either the L or R channel and delete it with your keyboard's "Del" key. Then you can copy the other channel and paste it into the empty one. Have you tried that?

[Dinosaur Punk]

Originally Posted by Alvaro Martín Gómez A.

I haven't tried Audacity, but I think that any audio editor should allow you to perform such a simple task like selecting either the L or R channel and delete it with your keyboard's "Del" key. Then you can copy the other channel and paste it into the empty one. Have you tried that?

I tried the steps described here, but audacity just deletes everything.

I know I can do this with Goldwave, but it involves manually opening all the files and pasting one track to the other. I am trying to be as lazy -- er -- efficient as possible.

[Stev187]

For many years, I have been a big fan of Polderbits, an audio capture/editing program.

PolderbitS Software - Easy to use Audio and Video recording software

I'm sure you can do this with other software, but you could simply pan hard L or R and then save the file as mono. One great feature of this software is track detection when converting LP records or tapes. Works great for capturing audio from your sound card (e.g. those tunes you can't find anywhere but a YouTube video, etc.).

--Steve

[Alvaro Martín Gómez A.]

Transcribe! converts the audio file to mono with just one click. Then you can export it in .wav or .aiff format.

[lunarpollen]

Usually, in most stereo file editing programs, to select only one channel and not the other, you have to click in the half of the waveform that is not adjacent to the other channel. Typically, the left channel will be the top waveform and the right channel the bottom one. To select ony part or all of the left/top channel, you have to click in the top half of the waveform and then drag to select the length you want (or typically, you'd double click to select all of it). To select part or all of the right/bottom channel, you have to click in the bottom half of the waveform...

If using an editor that allows you to select any part of the waveform in only one channel and not the other:

1. Select the whole waveform only for the backing track (probably double click)

2. Copy it (probably Ctrl+C)

3. Select the entire waveform of the other (bass) channel (probably double click)

4. Paste (probably Ctrl+V) the copied backing channel over it.

Then you should have both channels being the backing track.


If you must use Audacity, I think it won't allow for such editing, so you'd have to split the stereo track into two mono tracks via the Track pop-down menu. Then you should be able to save the backing track as a mono sound file. Click in the track's title and it should drop the menu down that will give an option to Split Stereo Track.

[JohnMCA72]

Goldwave lets you pick which channel to work with (default is both). You should be able to pick L channel only, select entire selection, copy, set R channel only, & paste.

Disclosure: I've never tried it, but I may do so later tonight just out of curiosity.

[Dinosaur Punk]

Thanks for the replies everyone.

Answering my own question:

I did wind up using Goldwave. I wasn't able to avoid re-encoding entirely, but it wasn't too bad.

1. Rip CD to WAV with Exact Audio Copy
2. Open first WAV with Goldwave
3. Shift-Ctrl-R Select Right Channel
4. Ctrl-C Copies
5. Shift-Ctrl-L Select Left Channel
6. Ctrl-K Pastes as over-write (note Ctrl-V pastes as append - not what we want)
7. Ctrl-F4 to Close
8. Repeat as necessary
9. Then Use Goldwave batch converter to convert to MP3

I did 43 tracks in 10 minutes with this method.

[Spectrum]

If you're only planning on playing it through one particular set of speakers, you might be able to save yourself a lot of trouble by getting a stereo-mono adaptor from Radio Shack. Might have to modify it so that it takes only the desired channel from the mp3 player and sends it to both the left and right speakers. I'm handier with a soldering iron than I am with software, so this is the first thing I thought of...

[Dinosaur Punk]

Originally Posted by Spectrum

If you're only planning on playing it through one particular set of speakers, you might be able to save yourself a lot of trouble by getting a stereo-mono adaptor from Radio Shack. Might have to modify it so that it takes only the desired channel from the mp3 player and sends it to both the left and right speakers. I'm handier with a soldering iron than I am with software, so this is the first thing I thought of...

Funny, I went down both of those paths as well. I'm a programmer by trade so the first thing I tried was software conversion.

Then it occurred to me I could do this with a couple of converter jacks. Came to about $3.75 on eBay, shipped. But they won't be here for about a week.

But today I was antsy and figured out a way to do it with software anyway.