I don’t recall this happening in the 1.x version of Audacity, but maybe I never tried it with such a quiet clip.
I took a clip out of a strummed guitar recording I made. I copied/pasted the clip and reversed the copy, then dragged it up against the original. I expected there to be a smooth transition, because the ending of the original is also the beginning of the copy. But that is not the case, as there is a popping noise at the transition between the two clips. Clicking the gap with the selection tool visually removes the gap, but the popping noise remains.
Attached is a pic of the clips at normal view and one zoomed in. In the latter you can see the gap, which I cannot close and is the apparent cause of the popping noise.
- Why is there a gap/pop between two identical end points?
- Why can’t I close this gap?
- Why is such a tiny gap producing a pop?
If you click on the vertical dark line so that it joins the clips, do you still get a pop?
Try putting them in their own tracks. You can align by using the tools that lets you slide a track forward or backward.
Did you use Edit > Find Zero Crossings where you made the split or selection, Gene?
Split Lines have always seemed to create energy differences in the spectrogram which I am not sure they should. Here is a spectrogram showing a split line created with CTRL + I at a zero crossing:
And here is the spectrogram after clicking to remove (merge) the split:
Is that a concern?
Steve: I guess you missed that in my post. Joining the clips makes no difference in the popping noise.
Gale: I didn’t know about Zero Crossings. That helped a lot. Thanks.
Themickster: Putting the 2 clips in separate tracks helped a little bit more. Thanks. (Though that is quite a pain )
Once I exported the tracks to mpg, the pop was even less noticeable. In fact I could hardly tell the difference between the single-track and two-track methods.
So from now on, if Zero crossings doesn’t work well enough in stereo, I will
- split the stereo into 2 mono tracks,
- cut with Zero Crossings,
- and if that’s still not enough, put the clips in separate tracks to slide them closer,
- put the 2 mono tracks back together as a stereo track. (Whew!)
However, I’m hoping there will be a way to eliminated the noise completely at some point in another version.
Thanks for all your help folks.
If you apply a short crossfade, that should eliminate the pop. See: Audacity Manual (in particular, the final example on that page).
If you mean step 2 cuts the two tracks separately, that could lead to different lengths in each channel and so desynchronisation.
As far as I can see, if you find zero crossings on two tracks starting from a given cursor point or selection, you may not get the same result as if you found zero crossings on a stereo pair starting from the same cursor or selection.
Also there is no guarantee with two tracks that the cursor or edges will be at zero crossings in both tracks, any more than that is guaranteed with a stereo pair.