Thick line in Waveform with 3.1.0

Since I updated from 3.0.5 to 3.1.0 the waveform/signal line is thick, even when there is nor signal running into Audacity.
I already tried changing the dB range that audacity shows on top, but the waveform line is still thick.

This is how it used to be with all older Audacity versions:
audacity normal line.PNG
This is now with Audacity 3.1.0:
audacity thick line.PNG
Any Ideas on how to fix this?

It does not matter, if I denoise my mic to the point where no signal is produced when quiet, or if I mute it…the db Meter on Top is showing absolutely nothing (showing down to -60dB) but the waveform shows the constant line so thick as if there was a constant signal active with 3.1.0.

I have noticed the same. And in addition there is some black dots in the line as there is signal in the silence.

If you select part of that thick line and press “Ctrl + L”, does it become a thin line?

Yes it does.

Here a recording with short test voice, then mute and a small section at the beginning was marked and silenced with Ctrl+L
Same Recording in spectrogram view:
So it’s clear to see that even with absolutely no signal, the line is thicker than the area that has been silenced with Ctrl+L

The “thick line” is showing you that there is a low level signal (probably just a bit of noise). If you zoom in vertically you will be able to see that it is a waveform (see:

I also noted this, when passing from version 3.0.2 to 3.1.2.
May it have anything with the change on Audacity’s built in volume control?
(now it changes its own volume instead of system’s volume)
It happens when recording from system’s “stereo mix”. It used to be completly silent.

It’s more likely due to the slightly different track geometry. In other words, just a slight visual difference rather than an audio difference.

In the spectrogram view it’s clear to see that even no signal is producing the thick line in waveform view.
I’ll stick with the old audacity version, because I can easily identify if there is any noice on my mic signal with the visual behavior in waveform view of the older version.

That statement contradicts what was said earlier in this thread. Perhaps you could give step by step instructions so that I can reproduce the issue and try to work out what is actually occurring.

OK so I dis some testing - first three images are with 3.1.2 second two are with 3.0.5

  1. this is “silence” recorded with 3.1.2 - and yes the line is thick (thicker than 3.0.5 - see image #4 below)
    01 thick black line.png
  2. I thun used Ctrl+L to silence the section from 5-7 seconds - and yes that shows as true silence
    02 thick black line - silence 3-5 secs.png
  3. I then amplified the clip - and we can see it’s not silence at all
    03 thick black line - silence 3-5 secs - amplified.png
  4. so I switched to 3.0.5 to repeat thee experiment - and yes we see a nice thin “silent line”
    04 thin black line - with 3-0-5.png
  5. I then amplified this - and we can see the recorded sigan is not silence in 3.0.5 either
    05 thin black line - with 3-0-5 - amplified.png
  6. for completeness I undid the amplify, silenced from 305 secs and then redid amplify
    06 thin black line - with 3-0-5 - silenced 3-5 secs and then amplified.png
    So yes that appears to be a slight visual difference from 3.0.5 to 3.1.x - but it may be that 3.1.x is swing a truer pictur and when quiiescent recording either my sound could is making a little “noise” - or it’s picking up “room tone”.


Here is some noise with an RMS level of around -50 dB in Audacity 3.0.2

First Track000.png
Here is the same track with the track height reduced sightly:

First Track001.png
Here is the same audio (from 32-bit float WAV) in Audacity 3.1.2:

First Track003.png
and finally, the same audio in Audacity 3.1.2 with the track size slightly expanded.

First Track002.png

At around -45 dB peak / -50 dB RMS, with the default track height, the waveform is on the threshold between one pixel high and two pixels high.
Audacity does not currently have sub-pixel rendering, so audio at this level may display as 1 or 2 pixels, depending on whether the rendering considers it to be closer to one pixel or two.

If there is sufficient track height, then the vertical height becomes closer to three pixels, and displays like this:

First Track004.png

I have the same issue with the thick line in 3.1.2. Here are some of the things I tried.

Opening the same track in 3.0.5 and 3.1.2 look totally different in the beginning silence.
I then split a track and generated silence to fill the gap. I then exported the file in wav, flac, m4a, and mp3.

I then reopened each file in Audacity 3.1.2.
As you can see, they all are thick lined in the silenced area with the exception of the mp3 file. It is the thin line at the top.

I then took the exported wav file and used Ctrl+L to silence again a section of the original silence in the wav file and exported to wav again.
When I reopened that file, the entire silence was thick lined again.

I can reopen all of these files in 3.0.5 and all of the silence areas have a normal thin line.

Since there seems to be an issue with 3.1.2, I have retreated to 3.0.5 in the meantime.

You are looking at two slightly different track sizes, so it should be no surprise that the two are not pixel for pixel identical.


You are right, It is because the 3.1.2 is adding the title at the top. That makes the waveform from 3.1.2 slightly smaller so therefor should be less noticeable. And what is the difference on the other examples that are on the same screen? And why do those exported clips show up fine in 3.0.5?

And why does it not show up on the Mp3 file in 3.1.2?

The way that audio samples are translated to pixels is extremely complex. It is not just a simple mapping of “sample value => pixel position”. At normal zoom levels each pixels represents many samples, and if there is room to do so will display both the peak level (dark blue) and the RMS level (light blue). The code also needs to be as fast as possible so that you are not waiting longer than necessary while Audacity redraws the waveform. If you resize the track vertically, you may observe that Audacity redraws the waveform to the new scale extremely quickly, even when there are millions of samples within the view.

If you silence a selection of audio (Ctrl + L) then you should see it as a thin (1 px) line. Is that what you see?

Noise with a peak amplitude of around -40 dB may show as 1 px or 2 px - it’s a borderline case and may do either depending on the track height, though with a very big track height it may show as 2, 3 or even 4 px high.

The “steps” in this image are simply an artifact of the pixel display, the actual audio fade is completely smooth (same audio in both screenshots):

First Track000.png
First Track001.png

So, I uninstalled 3.1.2 and reinstalled 3.0.2.
After recording silence from stereo mix, and amplifying (with both versions), the difference seemed to be only visual, still not sure, but seems that I mistook by worrying about this.

I hate to keep harping on this, but it is an issue that did not show up until 3.1.0 and I think, no I believe it had to do with the addition of the clip handle and here’s why.

As I stated before I did not see the issue in 3.0.5 or the older 2.42 versions. So, in version 3.1.3 I grabbed the bottom of the wave form to enlarge it vertically and when it enlarged by (I assume) one grid level the thicker wave line disappeared or returned to normal. So, I pulled it down one more level and the thicker line reappeared. This kept repeating as I enlarged the vertical view by one grid level at a time.
If you look at the left track at 0.0 you will notice the thickness of the line beside it.

Same track enlarged vertically by one gid level.

When there is a track loaded, it distorts the look of the fade-in of the track.
But when you enlarge it vertically by one grid line, the wave line looks normal.
So back to my original comment about it being related to when the clip handles were added, it changed how the default wave landed on the grid. I went back to versions 3.0.5 and 2.4.2 that did not exhibit this issue and enlarge the same track by one grid level at a time, and the silent lead-in wave enlarged the same way in both of those versions. That is what led me to believe it was the addition of the clip handles in version 3.1.0 and later.

Now with all of that being said, is there a way I could set a new default vertical height for when Audacity is initially opened so I don’t have to adjust the vertical height every time I open Audacity or drop a new track on it.