Re: [Audacity-nyquist] selection for analyzer plugs

[Domonkos N. <na...@ya...>]

David,

I am afraid you misunderstood me. The problem is not with extracting audio.
That is fine, I wrote quite a few plug-ins for my use that work with that.

The problem that I described is a "visual one" indeed, and briefly it is
due to the following. Let's say you have 4 samples in your waveform. If the
whole waveform is selected then the selection tool selects on the screen
from sample 0 all the way through till sample 4. Selection indicator starting 
exactly from sample 0. So when nyquist returns a list of values (for the label
track), 0.0 refers to the position of the first sample on the screen.

Now when you select a few samples, let's say sample 2 and 3, then the selection
tool's left edge is not above sample 2 but in between 1 and 2, hence nyquist 
returns 0.0 for the label track (as the sound passed in to nyquist still starts at 0.0)
which will refer to the start of the selection and not the position of the sample.

I hope this was clearer.

best,
Domonkos

On Tue, Nov 23, 2004 at 09:54:11AM -0800, David R. Sky wrote:
> Domonkos,
> 
> Since I'm using a screen reader, I cannot look at your images. However, I 
> have a suggestion. Based on what you wrote, it sounds like "zooming out" 
> will fix the visual problem.  Or you could use either the Nyquist extract 
> or extract-abs function to temporarily extract a portion of audio to work 
> with, and then undo it. I've posted an "extract by percent plug-in", let me 
> know if you'd like it.
> 
> Extract and extract-abs work like this
> 
> (extract start end sound) {extracting by percentage}
> (extract 0.0 1.0 sound) 'extracts' all the audio, there's no difference in 
> duration after the extraction
> (extract-abs {starttime} {endtime} sound} {extracting by time}
> 
> Extract literally removes just what you've defined from the rest of the 
> audio.
> 
> Dominic' asked that Nyquist-related issues only be postedd to the 
> development list if your Nyquist code crashes Audacity.
> 
> David
> 
> On Tue, 23 Nov 2004, Domonkos Nagy wrote:
> 
> >Hi,
> >
> >I started writing some analyzer plug-ins that work on individual sample
> >level and it seems that there is an annoying "shift" of sample start
> >times when the plug works on a selection and not the whole sample.
> >
> >To illustrate it I have attached the following files:
> > 1. i.wav - short sound (few samples) for the illustration
> > 2. mark_individual_samples.ny - nyquist plug to mark samples
> > 3. all_selected.png - illustrates when all is selected (how it should 
> > work)
> > 4. some_selected.png - illustrates the problem
> >
> >it seems that the start time of the sound object that nyquist gets is
> >not that of the first sample, but at the "graphical" start of the 
> >selection.
> >
> >It is quite annoying. Anyone knows where/how to report it as a bug?
> >
> >cheers,
> >Domonkos
> >
> 
> -- 
> 
> 
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