Subject: Re: [linux-audio-dev] matrix model vs. memory
From: Karl MacMillan (karlmac_AT_peabody.jhu.edu)
Date: Sat May 19 2001 - 23:36:36 EEST
On Sat, 19 May 2001, Paul Davis wrote:
> >> >What seems easiest to me is a LADSPA like plugin to manipulate the gain.
> >> >By making it an independent element on the graph it allows the normal
> >> >graph sorting to optimize the buffer usage. It is also the most flexible.
> >>
> >> Karl, please see my reply to Abramo. The question is whether the most
> >> fundamental method of transferring data from one port to another
> >> includes a gain coefficient. If it doesn't, then precisely how gain is
> >> implemented is irrelevant.
> >>
> >
> >Right - I am suggesting that a gain coefficient should not be included -
> >it just seems too complex and not nearly as effifient as the alternatives.
>
> Well, I don't think it is complex. As I mentioned, there is already an
> either implicit or explicit matrix of all the port connections. You
> can either assume that there is an implicit gain of 1.0 when data is
> moved from port to port, or you can include an explicit gain.
>
I guess I am confused - are you referring to moving data between inputs
and outputs in a single plugin or between ports on two different plugins?
If the latter, then data is not really moved, right? The output of one
plugin _is_ the input of another, so when would all of this happen?
> Its also much more efficient, since otherwise, gain operations have to
> consist of:
>
> src *= gain;
> dst = src;
>
> (with these two operations not occuring directly after one another,
> since they occur in different parts of the system)
>
> rather than:
>
> dst = src * gain;
>
> which occurs in one place.
>
Why is this?
> of course, such a model does not stop there being other gain controls
> present - i'm not suggesting that this be the only way gain is
> controlled. i am just wondering whether making the gain between two
> ports be explicit is a good idea, and it seems to me that it is.
>
> --p
>
_____________________________________________________
| Karl W. MacMillan |
| Computer Music Department |
| Peabody Institute of the Johns Hopkins University |
| karlmac_AT_peabody.jhu.edu |
| mambo.peabody.jhu.edu/~karlmac |
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