Shaped files distorting/warping

[blerb]

Hi,

I've used Audacity for about two years but I'm now encountering a new problem that is absolutely baffling to me. I would really appreciate some help with it. I'm using Audacity 1.3.13 Windows Beta on a Windows 7 machine. While I've been able to figure out any little hiccups I've had with the program in the past, this new thing is driving me crazy and I just want an explanation of why it's happening.

I produce a podcast with music buffers. To create the fade in and out effect cleanly, I use the Envelope tool to lower the track's volume gradually as the hosts begin speaking. I then fade the track out, add some silence, and fade it back in, effectively mirroring the process. Here's what it looks like in Audacity.



So, here's what things look like when I've got them assembled for the podcast. I copy/paste a bunch of files together because it lets me keep the music files stock, so I don't have to edit them every episode. It saves me tons of time and has worked fine until today for some reason. Here is the voice track at the top with the music at the bottom. I've copy/pasted two music files into the bottom track and place them together.



So, the little divider bar appears between the music tracks (I don't know how to turn those off, or I absolutely would... any help with that would be appreciated as well!). Normally I click on the bar and it goes away. But today, getting rid of the divider causes my envelop-tool shaped track to distort in a way that I can't understand the rhyme or reason of.



...I have no idea why it does this. Additionally, another similar problem is that when I paste my files into the podcast, I then add silence as needed until the next transition. That also seems to shift my envelope tool markers on the music track, which is not a problem I had before today. I have absolutely no idea why this is happening. I've never changed my Audacity settings. I'm sure there's a good reason but I just don't know why it is.

It test things, I did the exact same copy/paste into a file without the voice track (just the music). It produces no problems at all when I get rid of the divider bar between the two songs.




What am I doing wrong here? Why are my markers for the Envelope Tool distorting so much? Sorry if this makes little/no sense, I have no real training on this program so I don't know if the terminology I'm using is correct. I mostly figured it out for myself in my free time. If any more information would be helpful just ask. Any help is greatly appreciated.

[steve]

I think you may have trodden on a bug.
I've occasionally noticed weird things happening with envelope control points, but not often enough to pin down whether it's actually a bug or something I've done (though I suspect it a bug).

What I've done in the past as a workaround for the problem is to select the track, then use "Tracks menu > Mix and Render" so that the envelope if applied to the track. CAUTION - once you do this the only way back is with "Undo" (Ctrl+Z).

I'll do some testing and see if I can work out what is happening. If you find a repeatable way to create the problem, please post a step-by-step method - this will greatly assist the developers in tracking down and squishing this bug (assuming it is a bug).

By the way there is now a "release candidate" for the new Audacity 2.0. This version contains all of the features and bug fixes from the 1.3.x series, so it may be better to test with that version in case the problem here is due to a bug that has already been fixed.
Audacity 2.0 rc2 is available here: http://code.google.com/p/audacity/downl ... an=2&q=2.0
Before installing Audacity 2.0 you should manually uninstall Audacity 1.3.11

[billw58]

I haven't been able to reproduce the moving of the envelope when joining clips, but while attempting to do that I came across another envelope error.

Steps
Preferences > Tracks: "Editing a clip can move other clips" checked
Import two songs
Put them back to back on one track
Delete empty track
Using the envelope tool, apply a fade in and fade out to each track

Tracks faded with envelope tool

Screen Shot 2012-02-21 at 2.36.31 PM.png (28.17 KiB) Viewed 1516 times

Switch to Selection Tool
Generate 60 sec silence in middle of first song
Generate 60 sec silence in middle of second song
- envelope is moved

Envelope error

Screen Shot 2012-02-21 at 2.39.14 PM.png (29.39 KiB) Viewed 1516 times

- the apparent glitch at end of inserted silence in the first song is not really there - seems to be a waveform painting error

-- Bill

[steve]

I haven't been able to reproduce the moving of the envelope when joining clips,

Try this:

• Generate a 30 second tone.
• Split at 10 seconds and 20 seconds.
• Use the Envelope Tool to fade in from 20 seconds to 25 seconds (leaving the audio clip 10 to 20 seconds at full amplitude).
• Add an envelope point at 15 seconds and pull the level down so that there is a fade-out from 10 to 15 seconds and a fade-in from 15 to 20 seconds.

Fades applied

firsttrack000.png (8.85 KiB) Viewed 1499 times

• Click on the split line at 20 seconds to join the last two audio clips. The envelope goes wrong.

Join clips

firsttrack001.png (8.95 KiB) Viewed 1499 times

There's at least one bug here. It's been reported.

[billw58]

It looks confusing, but if you look at the AUP file before and after the join you can see what's happening, then looking at the wave it make sense.

Before the join there are two clips each with separate envelopes:

Code: Select all

 ... [clip starting at 10 seconds]
			<envelope numpoints="3">
				<controlpoint t="0.000000000000" val="1.000000000000"/>
				<controlpoint t="4.986251145738" val="0.184210538864"/>
				<controlpoint t="9.999977324263" val="1.000000000000"/>
			</envelope>
... [clip starting at 20 seconds]
			<envelope numpoints="2">
				<controlpoint t="0.109985834097" val="0.416666686535"/>
				<controlpoint t="4.894592117324" val="1.000000000000"/>
			</envelope>

After the join there is one clip with one envelope, 5 controls points:

Code: Select all

 ... [clip starting at 10 seconds]
			<envelope numpoints="5">
				<controlpoint t="0.109985834097" val="0.416666686535"/>
				<controlpoint t="4.894592117324" val="1.000000000000"/>
				<controlpoint t="10.000005000000" val="1.000000000000"/>
				<controlpoint t="14.986251145738" val="0.184210538864"/>
				<controlpoint t="19.999977324263" val="1.000000000000"/>
			</envelope>

What appears to have happened is this. 10 seconds should have been added to the times of the controlpoints in the second clip. Instead, 10 seconds has been added to the times of the controlpoints in the first clip.

-- Bill

[steve]

then looking at the wave it make sense.

It's still wrong, but yes it makes sense.
Good detective work Bill. Perhaps you could add a note to bug 474.

[billw58]

"Stretching" of an envelope when generating inside a clip.
New project
Generate tone, 300 seconds
Split at 150 seconds
Add 4 control points in the second clip to make a "U"-shaped envelope.

Select at 225 seconds
Generate 10 seconds silence or tone

Result: the envelope is distorted.

Before generating into the clip, the envelope control points in the second clip are:

Code: Select all

			<envelope numpoints="5">
				<controlpoint t="0.000000000000" val="1.000000000000"/>
				<controlpoint t="14.986251145738" val="1.000000000000"/>
				<controlpoint t="30.384967919340" val="0.111111104488"/>
				<controlpoint t="120.302474793767" val="0.097222208977"/>
				<controlpoint t="135.976168652612" val="1.000000000000"/>
			</envelope>

After generating into the clip, they are:

Code: Select all

			<envelope numpoints="4">
				<controlpoint t="24.986251145738" val="1.000000000000"/>
				<controlpoint t="40.384967919340" val="0.111111104488"/>
				<controlpoint t="130.302474793767" val="0.097222208977"/>
				<controlpoint t="145.976168652612" val="1.000000000000"/>
			</envelope>

Note that:
1) the control point at the start of the clip has been removed (why?)
2) 10 seconds has been added to all the control points in the clip, when in fact 10 seconds should have been added only to clips after the selection point.

Note that this does not happen when generating into the first clip when the first clip has envelope control points.

While both cases I've investigated involve errors in recalculating envelope control points, they are "different" errors.
1) In the case of joining clips, time is added to the control points in the wrong clip
2) In the case of generating inside a clip, time is added to all control points instead of only those control points after the selection.

-- Bill

[steve]

The plot thickens.
I'm glad that I mentioned in the bug report that there may be more than one bug here.

[Gale Andrews]

I think this is is probably fixed as of the 27th February, thanks to everyone who tested. @Blerb, if you want to test, you can download:
http://audacity.googlecode.com/files/au ... 2.0rc5.exe

or if you prefer a zip file that does not have to be installed:
http://audacity.googlecode.com/files/au ... 2.0rc5.zip .


Thanks,


Gale