How can I convert stereo mp3 to mono WITHOUT reencoding?

[Paco M.]

Hi,

I have several stereo mp3 files with voice recordings. I need to convert them into mono in order to reduce their size. Original quality is not very good so that I would prefer not to reencode them.

Does anyone knows how can I mix both channels (or extract one of them) without mp3 reeconding?

Thank you in advance for your suggestions.

Paco

[mats.hogberg]

Nope. No can do.

/Mats

[Paco M.]

What a pity!

There are other operations, like audio normalization, that can be done without reencoding. I expected so for stereo to mono conversion but .....

[guns1inger]

I haven't normalisation done without re-encoding. MP3Gain can lift the gain of a file without re-encoding, but I don't believe it actually normalises the file. It can match the gain across a folder of tracks to give them a common volume - which is a type of normalising, I guess, but not in the manner you mean.

Regardless, what you are talking about is a structural change to the audio, so no dice

[ebenton]

Have you tried just using brute force, with a "y" adapter cable to connect both left and right to one cable, and then input into whatever mono recording device you want to use?

[mats.hogberg]

That wont make the MP3 files much smaller in size...
I think the only way is to reencode to mono MP3 - don't really think the quality will suffer that much.

/Mats

[ebenton]

I did not gather from the original post that reduced size was a goal.

[SingSing]

Too much sun shine for you.

[jagabo]

I did not gather from the original post that reduced size was a goal.

I need to convert them into mono in order to reduce their size.

[mats.hogberg]

No need rubbing it in, guys! I think ebenton got the point long ago... We're all guilty of not reading every word before replying once in a while...

/Mats

[moviebuff2]

Hi Paco M.:

If you still want to convert your stereo files to mono, without reducing the size, Audio Cleaning Lab (ACL) may be of your interest. Actually, ACL may even improve the quality of your files.

Cheers

[Paco M.]

Thanks moviebuff2. I will look into Audio Cleaning Lab (I do not know this application) although I am mainly interested in reducing the size of the files by converting them from stereo into mono ... without reeencoding.

[Enygma]

Since they are only voice recordings, have you bothered to check to see if the left and right channels are identical? Often times "stereo" sound clips are really mono but copied to both channels.

I'm not sure what software you could use to remove one of the channels and change it into a mono mp3.

For simplicity sake I would suggest re-encoding anyway. You won't lose that much quality for voice recordings.

[jman98]

I'm not sure what software you could use to remove one of the channels and change it into a mono mp3.

Cool Edit or a similar audio editor can easily remove one channel and change a file into mono. I find it easiest to do this with the batch converter in Cool Edit.

[Noahtuck]

Why even bother removing a channel ?
Open it and if it's a stereo file just save it as a mono file 8) 8)

[psx_pirate]

Sony Soundforge (not cheap) can do it .... just use the channel converter to convert from stereo to mono

NOTE: converting from stereo to mono will not reduce the file size ..... so save your money .... only by re-encoding to a lower bitrate will you reduce the filesize

[Noahtuck]

Hmmm...
Funny... i just opened a true stereo music file that was 977mb, changed absolutely Nothing, just opened it in Sound Forge 8.0, and saved it as a mono file and it is now 488mb 8)

[mats.hogberg]

The problem wasn't how to convert a stereo MP3 to mono MP3 - it is doing it without reencoding.

/Mats

[Noahtuck]

Yep, i knew that
I'm still wondering why you would not just do it and see how it sounded
Also i tested it with a wav and it did lower the file size but not with an MP3,
Even if one side of the MP3 is muted then saved as a mono MP3 it does not reduce the size.
Man i hate MP3's :P
Oh well 8)

[psx_pirate]

Using the channel converter in Sony Soundforge does not re-encode the mp3 .... and like i said previously it won't reduce the file size either .... converting mp3's from stereo to mono will make no difference to the file size

[Cornucopia]

The only apps that have been known to manipulate an mp3 stream WITHOUT re-encoding it have been: A-cut/join editors, B-ID3 tag editors, C-playback gain editors

Unless you have evidence to the contrary (and I'm sure we'd all like to see that), I don't believe it's possible for Soundforge to do what you say--WITHOUT reencoding the mp3.

Now, IN THEORY, it ought to be possible for an mp3 parser to see only the packets for each channel and reroute them to a new file, with new channel flags inserted. This would change the file, but not the payload data stream itself (at least for that channel). Problems would arise if using shared bitrate allocation, because then the remaining bitrate setting might not fit into one of the Legal choices.

Still, nobody has yet created such an app that I know of...(any takers?)

Scott

[moviebuff2]

Hi,

I have several stereo mp3 files with voice recordings. I need to convert them into mono in order to reduce their size. Original quality is not very good so that I would prefer not to reencode them.

Paco

I think the main concern is the audio quality that makes Paco M. to not want to re-encode.

Therefore, if an audio cleaning software can: 1) convert the stereo files to mono and 2) improve the quality of the original files (de-hiss, de-noise, de-clip, pitch correction, etc.), the re-encoding will not be an issue.

My vote: Audio Cleaning Lab. Ther current version is 11. But the earlier versions will do the job and I believe Magix (the maker of ACL) gives them free of charge.