MP3 properties 'Stereo' versus 'Joint Stereo'

[T_Scheen]

Well, I am not really an mp3 expert but maybe someone knows the answer. I use Videredo and TMPGNC to rip the music from DVD-VOBs into wav-files. Then I use another program to convert that into mp3. Before encoding, that program asks me whether I want "Stereo" or "Joint Stereo". I don't know the difference.
When adding a background music in Ulead MF3.5 (mp3-format), I can see the properties of that file as well by clicking "Info". Some of my mp3s are "Stereo" and others are "Joint Stereo". Both work of course but does anybody know the difference ?

Thomas

[phd]

Joint Stereo: This option can convert the sound to mono in the lower frequency range. It enhances stereo quality in the mid to high frequency range. The setting is useful if the audio bitrate is below 200Kbps.

[T_Scheen]

OK - Thanks !

[Anonymous]

See http://harmsy.freeuk.com/mostync/ to understand how JS works.

It is even used in lossless compression codecs.