Re: [ecasound] I think this has been asked before ... but ...

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Subject: Re: [ecasound] I think this has been asked before ... but ...
From: Jeremy Hall (jhall@UU.NET )
Date: Thu Jan 13 2000 - 09:33:59 EET


If you right-shift the left channel by a factor of say 50%, then move it
back, you end up with zeros on the "right" side of the left channel.

I am probably not making sense to you because you are thinking in terms of
DSP and I am just thinking. :) (I do not understand DSP well and would
like to know how it works)

so what I am trying to do is delete the center channel, meaning, if a
person is talking, his voice is on center, meaning, if you listen to him
talk, he is appearing to be in center focus rather than off to the left or

I want to remove his signal, yet preserve the rest with a band filter,
except the band is not frequency related, rather it is a scale between 0
and 100, 0 being left, and 100 being right. so on this scale, if something
represents a 50, I want to remove it. With a center freq of 50, and a
width of 50, the user wishes to delete all signal that registers between
25 and 75.


In the new year, Kai Vehmanen wrote:
> On Tue, 11 Jan 2000, Jeremy Hall wrote:
> > I want to supply negative numbers to -epp, as well as supplying numbers
> > greater than 100.
> Hmm, I don't think you do. ;) Currently ... -epp:0 does the same
> as -eac:0,1 ... -epp:100 is same as -eac:0,0 ... So if -epp is isn't
> enough, channel-amplify should do it.
> > ecasound -a:1,2 -i /tmp/in.raw -o /tmp/out.raw -a:1 -epp:-20 -a:2 -epp:70
> [...]
> > This has the fortunate effect of chopping a center channel out when
> > combined.
> Hmm, can you explain this some more...?
> > Ideally, we could have two new effects that would be similar to a band
> > pass and band reject filter, except these are ban-pan-pass and
> > band-pan-reject filters. In a pan reject filter, supplying a center of
> > say 75 and a width of 50 would dump the right channel. A more
> > constructive use would be to try to mute a center channel, or accentuate
> Now I'm confused. ;) If you want to find the common parts (= center
> channel) between different channels, I'd suggest using
> a combination of -eac:-100,channel (invert phase) and various filters.
> Panning won't do you much good. Hope I understood what you meant to say.
> --
> Kai Vehmanen <> -------- CS, University of Turku, Finland
> . - linux audio processing
> . - ambient-idm-rock-... mp3/ra/wav

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