Envelope tool not affecting playback

Sometime between last night and today, audacity started having trouble with the envelope tool in one of my audacity projects.

New audio segments that I try to use the envelope tool on will visually look like the envelope was applied correctly, but the reduction in volume will not be applied during playback, or will be applied for a split second and then jump back to full volume. Old segments in that same project that already had the envelope tool applied appear to be playing back at the intended volume. Copying the whole track (where some segments play at their intended volume and some don’t) into a fresh project leads to the same undesired behavior. If I start a completely fresh project, the envelope tool seems to work properly again.

Left segment is new and plays back significantly louder than right segment, which had had the envelope applied before this issue showed up
Same two segments after a lossless export:
I just now remembered that audacity crashed earlier today when I tried to apply the “change pitch…” effect with “use high quality stretching” checked, but I can’t remember if that was before or after this problem first showed up, so I’ve included the debug report generated then too.

Linux version: Ubuntu 18.04.5 LTS
Audacity version: 2.4.2
Installation method: Snap I think? Happy to follow instructions to find more details if necessary
Audacity_dbgrpt-8109-20210109T114851.zip (15.2 KB)
Audacity_dbgrpt-29793-20210109T171341.zip (16.1 KB)

  • I meant to name this topic “Envelope tool not affecting playback” rather than note affecting playback. Whoops

That’s a known problem in Audacity 2.4.2. It has been fixed for the next Audacity release.

The crash only occurs with the HQ setting, and only on Stereo tracks, so the workaround is to either use “standard quality” (HQ stretching turned off), or split stereo tracks before stretching and then join back into a stereo track after (see: Splitting and Joining Stereo Tracks - Audacity Manual)

This bug affects: Change Pitch, Change Tempo, and Sliding Stretch.

What if you copy part of a track to a new project rather than the whole track?

I’m still getting the same playback issue where the envelope tool on the first segment is applying only to part of the segment or not at all. The new project is now small enough (1.8 MB) and feels anonymized enough that I’d be willing to upload and share the whole thing if that would help. Please let me know what the recommended way to do that is if you would like me to do it.

Side note: I was reading around last night and saw that the Snap install of audacity isn’t recommended, so I uninstalled it, added the unofficial PPA, and then re-installed Audacity via the command line, so that’s the version of Audacity 2.4.2 that I’m running now.
Audacity_dbgrpt-26125-20210110T110139.zip (7.92 KB)

Please do.

Oh, it looks like I can just attach it here. Done.
mirror-partial.zip (1.55 MB)

Interesting. I can see the problem, and can see how to fix it, but it’s very strange.
I think it is very likely that it occurred when Audacity crashed with the “change pitch” effect.

That little project has a “phantom” audio clip between the two visible clips.

To fix it:

  1. Select the Time Shift Tool.
  2. Drag the right hand clip a little way to the right
  3. Switch back to the normal Selection Tool
  4. Click on the right hand edge of the first clip. You will probably see the edge change from a thick black line to a thin black line.
  5. Switch back to the Time Shift Tool.
  6. Drag the second clip back to where it started.

Step 4 joins the “phantom” clip to the first clip, so now there are just two normal audio clips.

Huh. That is in fact bizarre and the fix does in fact work.

I guess my problem is fixed, but the fact that “phantom” audio segments can exist and affect the playback of some other segment seems problematic

A few strange properties of the “phantom” audio segment, determined experimentally (I was not particularly scientific about this, so this might not apply in all cases):

  • If I move the left segment instead of the right one, the thick line you described does not appear, and clicking the right side of the first segment does not change anything

  • The phantom audio seems to be tied to a particular time stamp and linked to that particular segment, so moving the linked segment (1) doesn’t fix the playback issue and (2) means you know don’t know where the phantom audio segment is to get rid of it

  • The phantom audio does seem to exist enough to prevent you from using the time shift tool to move something over that spot, so I guess that’s one way to find them

  • It looks like if you can get any segment aligned to the phantom segment such that a thick black line appears, you can join it out of existence

  • Also I think if you move both segments away from that spot and then delete the empty space between them, that seems to be able to get rid of the phantom segment too

One of Audacity’s “advanced” features can locate the “phantom” clip.

  1. Enable the “Extra” menu with the option near the bottom of the “View” menu.
    Observe that a new main menu item appears.

  2. “Extra menu > Scriptables II > GetInfo”

  3. Set “Type” = “Clips”

The output:

  { "track":0, "start":3.1891, "end":4.83771, "color":0 },
  { "track":0, "start":4.83771, "end":8.0769, "color":0 },
  { "track":0, "start":4.83771, "end":4.83771, "color":0 } ]

Observe that the third clip has zero length, and has the exact same time as the end of the first clip.