🚀 go-pugleaf

In article <g9pj_8-.mcmahan@netcom.com> mcmahan@netcom.com (Dave Mc Mahan) writes:
>
> In a previous article, zong@imec.UUCP (Zong Liang WU) writes:
>>Hi net-landers,
>>
>>I am interested in removing voice from background 
>>accompagning music. The idea is that you have a CD of
>
>Here in the USA, they sell small boxes that claim to be able to accomplish
>this task.  My understanding of how they work follows.  I have no idea if
>
>When a song is recorded, the standard method is to create a stereo signal.
>The right channel has some instruments, the left channel has some others,
>but the voice is placed on both channels.  By inverting one channel and
>summing it with the other channel, a box will subtract out all signals common
>to both channels.  This can tend to remove some of the instrumental background,
>but it is supposed to do a fairly good job at removing all of the voice.

Some material deleted...

   I built one of those machines about four years ago and sold it as a stereo
enhancer. The stereo information is "difference" information so if you add to
each channel the "center" information you improve the stereo perception. This
device also tended to diminish or eventually eliminate the voice since it
subracted the centre information, however the quality of the outcoming music
was more an echo with a "space-like" quality than the original instruments
without music. It was a very nice add-on though when a reasonable amount of
"difference" signal is fed into the front loudspeakers or completely into some
"back" loudspeakers.
   It is very hard to extract ONLY the instruments. What karaoke companies do
is get tapes of the instrumental channels of a 16-channel tape of a performance
which has one,two or three channels ONLY for voice and not use them in the final
mix.

-- 
         -----> All opinions expressed here are my own, not IBM's <-----
Raul Izahi Lopez	IBM Bergen Environmental Sciences and Solutions Centre
izahi@bsc.no	        Izahi Engineering is here !!!