Re: [Audacity-nyquist] selection for analyzer plugs

[David R. S. <sk...@wa...>]

Domonkos,

Sorry, I do not understand yet, probably because I have not yet worked with 
individual samples in Nyquist. But it's something I want to learn about.

David




On Tue, 23 Nov 2004, Domonkos Nagy wrote:

> 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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>
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