Re: Status report on Gnome Wave Cleaner, and possibility of plug-ins

[torben hohn <torbenh gmx de>]

On 18 Sep 2002 21:13:36 -0700, Jeff Welty wrote:
> There is a development release (0.17-2) of the Gnome Wave Cleaner at:
> 
> http://gwc.sourceforge.net/
> 
> Many people have asked for plugins of the declicking and denoising
> algorithms.  This is a complicated task -- LADSPA plugins will not
> be possible.  The algorithms do not operate on a window at a time,
> they must look ahead (or sometime behind) of the current window to
> repair the data.

how much behind and forward ?
is that a bounded value ? (assuming yes)

then you could delay the input signal.
the denoising algorithm could then use the delay buffer to
get the data from the future.

The plugin would have to tell the host how much delay it imposed on the
signal.

> 
> The strategy I am taking (slow, as it is ;-), is to
> start creating library functions for declicking and denoising.  The
> basic idea is that the algorithms will ask for input data from a
> function pointer passed to the algorithm, and once enough data
> has been processed, the algorithms will start sending cleaned data "out"
> via a different function pointer.

this is a viable path.



> Once library functions exist, then I hope that it will be easier to
> determine requirements for a pluggin API that would support these
> algorithms.  Probably then also, someone smarter than me could make
> the libraries into pluggins.  It would also be possible to code
> stand alone programs that would read from stdin, write to stdout...

i will make the galan plugins :)


> 
> I will once again caution that proper denoising requires a proper sampling
> of the noise -- applications could try to find "noise only" regions and
> pass that to the denoising algorithm, but with some chance of really mutilating
> the wanted audio portion of the signal.
> 
> Jeff Welty
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> http://mail.gnome.org/mailman/listinfo/gnome-multimedia
> 


Torben Hohn
http://galan.sourceforge.net