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
ok
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
right.
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.
_J
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 <kaiv@wakkanet.fi> -------- CS, University of Turku, Finland
> . http://www.wakkanet.fi/ecasound/ - linux audio processing
> . http://www.wakkanet.fi/sculpscape/ - ambient-idm-rock-... mp3/ra/wav
>
>
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