TimeLine Overshoot

[kozikowski]

Mac Audacity 1.3.5b. I'm trying to rapidly edit a half-hour stereo show and I noticed that when I selected a portion at the end, the cursor, although it snaps to the end of the waveform, will keep going into virgin territory if I keep pushing by accident. Why does it do that and can I get into trouble applying effects that "spill over?" Just deleting unneeded sound from the end doesn't seem to make any difference.

Koz

[steve]

Let me check that I understand the question.

Say you have a show that is exactly 30 minutes duration.
You select a region that starts at 28 minutes, and extends to 31 minutes.
Question 1 - why is that possible when there is nothing after 30 minutes?
Question 2 - is this ever a problem?

If I've got that right;
There are a few circumstances when being able to select beyond the end of a track can be useful. Examples include:
Using the "Generate" functions.
If you want to apply a partial fade out (not down to silence).
If you want to set labels that go beyond the current audio in your project.
If you want to paste an audio clip beyond the end of the existing track.

I've not noticed any problems with this.

[kozikowski]

<<<Using the "Generate" functions.>>>

Since as far as I know all the generate functions are "flat" and don't change over time, you wouldn't need timeline overshoot. Some filters take information from the timeline before they act and extending the selection into blank timeline would create unstable sampling.

<<<If you want to apply a partial fade out (not down to silence).>>>

I know it's bad form to compare packages, but Cool Edit gets around that by allowing you to pick the beginning and end fade points as well as pre-packaged fades. Back in Audacity, that effect can be accomplished with great stability and control in the envelope tool.

<<<If you want to set labels that go beyond the current audio in your project.>>>

Since we know that labels are beginning markers, not separators, why would you possibly want that? As far as creating trailing silence where none had been before, that's insanely dangerous unless you actually add or paste silence. "Silence" and blank track are different.

<<<If you want to paste an audio clip beyond the end of the existing track.>>>

You can't just press "End" and "Paste" whatever those keys are on your machine? All the editors I've ever used just extend the existing track when I do that.

My concern is what happens if I accidentally Do Something beyond the natural End Point. I can see programming mistakes where the show and the blank timeline are in different audio standards. Think of how much fun that would be to troubleshoot. And no I'm not making that up. Think of how much fun extending the timeline into negative numbers was further up the forum. Rather than try to fix either of those problems in code, I would totally make it so you simply couldn't do it.

Koz

[steve]

Since as far as I know all the generate functions are "flat" and don't change over time, you wouldn't need timeline overshoot

Taking the example of a 30 minute track, if you want to generate "Chirp" from 29 minutes to 31 minutes (overwriting the last 1 minute of the original track), the quickest and easiest way to do it is to select with the mouse the region from 29 minutes to 31 minutes, then generate the chirp. There is no need to enter the duration in the "Chirp" interface.

In the case of "Chirp", the interface offers an alternative to selecting the desired region, but what if we were wanting to use a Nyquist function such as the example below? In this case the sound generated will be of the length of the selection and there is no alternative way of defining the selection.

Code: Select all

(mult 
(lowpass4 (highpass4 (scale 0.3 (comb (noise) 256 140)) 30) 400) 
(env 0.1 0.1 1.0 3.0 1.0 0.3 1.0))

To try this out, select part of a track, then select the Nyquist Prompt from the effects menu, and paste that code in the box.

Back in Audacity, that effect can be accomplished with great stability and control in the envelope tool.

Creating the same kind (shape) of fade as the cross-fade effects using the envelope tool requires entering multiple control points and is very fiddly to do. Even with multiple control points the shape of the fade is still an approximation to the effect that is attained using the cross-fade effect.

In the example below, the desired fade was created in the lower track by selecting the region from 1.548 seconds to 1.888 seconds and applying the cross fade effect. This took about 5 seconds to achieve. The upper track achieves a similar effect by carefully placing 5 control points to create the envelope - this took a lot longer.

cross-fade.png (8.66 KiB) Viewed 1176 times

Since we know that labels are beginning markers, not separators, why would you possibly want that?

You are assuming that we are adding labels after we have finished out recording/editing.
If I am part way through a project, I may know in advance that I want a particular section of my music in the region 3 minutes 20 seconds to 3 minutes 40 seconds. I can label this section in advance (with a meaningful name) even though I do not yet have any audio in that section. When I am ready to add some audio to that section, I can quickly select that region by clicking on the name of the label.

There are many other times when selecting "dead space" can be useful. I guess that it is not common when Audacity is being used for transfering cassettes to CD, but they can be quite common when creating music, and removing this feature would be unpopular among many users that use it (including myself).

Since you mentioned Cool Edit, the Pro version (and Audition) will allow you to select "dead space" when in the multi-track view, just as you can with Audacity (which always uses a multi-track view).

I am unsure why this is an issue - have you found some situation where this causes a problem?

[kozikowski]

<<<have you found some situation where this causes a problem?>>>

Not yet. Regard the comedy routine where a performer leans on a desk and he's off by about six inches. When I'm rapidly editing and selecting it's a little unnerving when I get to the end of a performance...and the cursor doesn't stop. There is the unmistakable impression that the program is expecting me to stop long enough to accurately hit the sticky End Of Performance point.

Koz