Stereo to Mono -Sound Forge - PC - MAGIX Community Forums Archive

Subject:Stereo to Mono Posted by: mark_960 Date:10/14/2002 7:45:53 AM I am in the process of converting MP3 music tracks from Stereo to Mono. To my surprise, the resulting file essentially the same size is the same as the original. I was expecting the mono files to be half the size of the original. What's happening??? The only way I've been able to reduce the MP3 file size is to reduce the Kbps from 128 to 96. Unfortunetly, my MP3 player does not support 64Kbps.
Subject:RE: Stereo to Mono Reply by: Ted_H Date:10/14/2002 11:26:59 AM I was expecting the mono files to be half the size of the original. This is true with WAV files, but not mp3's unfortunately. I don't know enough about mp3 compression to tell you why, but I do know that much. Ted
Subject:RE: Stereo to Mono Reply by: Chienworks Date:10/14/2002 3:39:12 PM From what little i've read on the subject, my understanding is that MP3 Stereo (and other compression methods as well) make the assumption that the two channels are often very similar most of the time, so the majority of the compressed signal is mono with a small bit of information that describes the difference between the channels. The decoder then uses this difference information to generate the left & right channels from the mono signal. I might be completely off on this, but it would explain why the mono & stereo versions are similar in size. One other thing to consider: when you render to MP3 you specify a bitrate for the file. If you normally render your stereo files to, say, 128Kbps, then to get a file half that size you would need to render to 64Kbps whether you're using stereo or mono. The average bitrate multiplied by time defines the size of the file, not the number of channels.

Subject:Stereo to Mono

Posted by: mark_960

Date:10/14/2002 7:45:53 AM

I am in the process of converting MP3 music tracks from Stereo to Mono. To my surprise, the resulting file essentially the same size is the same as the original. I was expecting the mono files to be half the size of the original.

What's happening???

The only way I've been able to reduce the MP3 file size is to reduce the Kbps from 128 to 96. Unfortunetly, my MP3 player does not support 64Kbps.

Subject:RE: Stereo to Mono

Reply by: Ted_H

Date:10/14/2002 11:26:59 AM

I was expecting the mono files to be half the size of the original.

This is true with WAV files, but not mp3's unfortunately. I don't know enough about mp3 compression to tell you why, but I do know that much.

Ted

Subject:RE: Stereo to Mono

Reply by: Chienworks

Date:10/14/2002 3:39:12 PM

From what little i've read on the subject, my understanding is that MP3 Stereo (and other compression methods as well) make the assumption that the two channels are often very similar most of the time, so the majority of the compressed signal is mono with a small bit of information that describes the difference between the channels. The decoder then uses this difference information to generate the left & right channels from the mono signal.

I might be completely off on this, but it would explain why the mono & stereo versions are similar in size.

One other thing to consider: when you render to MP3 you specify a bitrate for the file. If you normally render your stereo files to, say, 128Kbps, then to get a file half that size you would need to render to 64Kbps whether you're using stereo or mono. The average bitrate multiplied by time defines the size of the file, not the number of channels.