Align similar tracks exactly

[carl_aix]

Hi all,

I am using Audacity 2.3.3 as packaged in Debian Bullseye. To prepare my question I have to describe my editing process of a simple mono track:

1. I cut a part from the beginning of the track.
2. I moved the remaining part to the beginning.
3. I cut another part from the end of the track, leaving a part of about 35 seconds.

Now for a different project, I need nearly the same result, but with a later splitting point for (3.). I still have the original, un-cut file. My question therefore is: Is there any way to detect that tracks are the same except for an offset?

Thank you for your suggestions,

Carl

[steve]

I don't understand what you are asking. If both projects are simply different edits if the same file, then you already know that they are the same except for an offset, so why do you need to test?

[carl_aix]

Please excuse my bad explanation. I want to create a longer version of the track that I split before. This new version should start at the same point as my first edit.

For achieving this by working on the original, my thought was to align the original track and my first edited version at the edited version's start or end. Then I could delete the superfluous part at the beginning of the original track; and finally I could split this at a later time than my first edited version.

If there is any different possibility to achieve this, I am happy to learn about this. I am new to Audacity and this was my first idea about how this could work.

[steve]

If I understand correctly,
You have two audio files.

• File "A" is the original.
• File "B" is a copy of "A".
• File "B" has been trimmed at both the start and the end so that it is shorter than "A".

You want a new file / audio track ("C"), that:

• is a copy of "A",
• is trimmed at the start the same as "B",
• has less trimmed from the end than "B" had, so that it is longer than "B".

and the part that you want help with is:

• how to trim the start of "C" so that the start of the track is the same as "B"

If I've got that right, then it's not hard to do, but does require some careful, manual editing (there is no way to automatically / magically align the tracks).

The way to do it is to import both "A" and "B" into Audacity:

Tracks001.png (23.27 KiB) Viewed 113 times

Line them up approximately by eye, using the Time Shift Tool.

Tracks002.png (23.3 KiB) Viewed 113 times

Zoom in on track "B" and find a part that is easily recogniseable:

Tracks003.png (28.35 KiB) Viewed 113 times

Adjust the position of "B" so that it matches more closely with "A"

Tracks004.png (30.83 KiB) Viewed 113 times

Continue zooming and adjusting until the tracks are precisely aligned.
It can help to switch back to the normal selection tool (F1 key), click on the upper track, then press the "down" cursor key, so that you then have a vertical line spanning the two tracks like this:

Tracks005.png (34.62 KiB) Viewed 113 times

"F5" key to go back to the Time Shift Tool.
Note that you can move the vertical line left / right with the left / right cursor keys.

Tracks006.png (35.61 KiB) Viewed 113 times

When you have the position as accurate as required, zoom back out as necessary to see the start of track "B".
Switch to the normal selection tool ("F1") and double click on the audio clip in track "B" to select it:

Tracks007.png (40.46 KiB) Viewed 113 times

"Up" arrow, then "Enter" to add track "A" to the selection, then "Ctrl + i" to "split" the track:

Tracks008.png (40.67 KiB) Viewed 113 times

Click on the right hand split line to "join" the split, then double click in the left hand clip of track "A"

Tracks010.png (40.61 KiB) Viewed 113 times

You can now delete the selected start of track "A", and hopefully that has done what you wanted.

[carl_aix]

This is exactly what I wanted. Thank you for your detailed explanation!