What is "Merge," exactly?

I’ve been digitizing some old cassettes. It’s been going well. But there’s one where I want to copy a section of audio and paste it at the end of the track.

When I do this, a thick black vertical line shows up on the waveform at the joining point where I paste the repeated section. If I click on it, it goes away, and in the “edit” menu, I have the option to “undo merge,” implying that the clicking of the black line enacted the “merge” function.

Is this necessary? The wav file I export seems to play the same whether or not I click the black line to make it disappear.

When you paste at the end of a track (as opposed to in the middle of it), you are creating a “clip” within the track which can be manipulated separately from the audio to left of it. For example you could drag the clip to right to create space to left of it, or double-click in it to select all of it but not any audio or space to side of the clip.

The boundary of the clip with other audio is marked by a black vertical split line. “Merge” removes the split line and joins the two clips into one.

Please see this link for more details http://manual.audacityteam.org/o/man/audacity_tracks_and_clips.html .


Thank you. When you say “as opposed to the middle of it,” how would that be different? I ask because I may end up moving the end of the recording to the middle of it, rather than moving a middle part to the end. And am I correct in assuming that the exported wav is the same regardless if I make the black merge lines disappear or not?

Because pasting in the middle of a track does not create a separate clip, hence there are no black vertical split lines. But if you paste at the end of a track, that paste is regarded as a separate clip and that clip’s border with the existing audio is then shown by a split line.

Yes, the same. Exporting or any render operation (see Tracks > Mix and Render) merges the audio into one piece. Any white space between clips is rendered as silence. Many of the effects underneath the divider in the Effect menu also render white space as silence, but that is a bug rather than a feature.


Though it is possible to paste in the middle of a track as a separate audio clip if you want to.
If you have copied some audio, click in the middle of a track and paste, the pasted audio will not be separate - it will be part of the same audio clip (no split line), but;
If you click in the middle of a track and then press Ctrl+i (which creates a split line) and then paste, it will be a separate audio clip (split lines at the start and end of the pasted audio).

There’s also a “join” option at the Edit dropdown, (2.0.3), under the “cut” or “delete” (don’t have the Program open right now) that does the same thing. The whole track is highlighted, then the black separation lines disappear.