Alignment probem exporting and importing

I am exporting using export multiple into a mp4 format, several different tracks some that have been overdubbed. They sound fine before export but when I try and import them the are not lined up. I did a latency test before overdubbing and it was fine. But when I imported them back into audacity the overdubbed track would not line up. I’m trying to send this to a friend so he can add a part in Audacity. Any help will be appreciated.

I probably would not do that in a compressed format. The compressed formats, MP3, M4A, etc are Delivery Formats. That is, make an M4A out of the final show, Full Stop, not steps in the middle of production. You should avoid production in those formats because every time you overlay another instrument or voice, the compression distortion and damage is going to go up, too and probably destroy the show as you go. Those small files are not free.

You can Export all the layers as WAV to avoid those problems, but you might try Saving an Audacity Project instead. You will get an AUP Project Manager text file and a _DATA folder with all the pieces and clips in it to make up the show. The person at the other end opens up the Project and picks it right up where you stopped without having to reconstruct all the layers. Layers are automatic.

After you make your project, Zip it before shipping so the parts of the show don’t get damaged on the way. If the show is small enough, you might be able to do it via Drop Box for free or one of the other file sharing services.


Further to Koz’s answer, the following might help you for final export if the problem is that space between time zero and the start of the audio was removed in the export.

To solve that, select a little audio starting at time zero and Generate > Silence. The selection does not need to go all the way up to the start of the audio.

Or Edit > Select > All, click in the grey background underneath the last track, then Tracks > Add New > Audio Track and Generate > Silence. For straight export (mixdown), this ensures that silence before the audio starts will be preserved. If none of your tracks start at zero, then after Edit > Select > All, use SHIFT + HOME to extend the selection to start at zero.


Everybody wants to make this song into a fancy Skype-sync performance, but Josh posts that they all simply sung their own parts in their own cities and send the final files to him for integration into one song. He never said what they were using for a sync track, though. Is that where you’re stuck? I would not depend on the start points to match without juggling, but the Clip Duration should work.


I tried exporting them as wav files using export multiple, but when I imported them back into a new audacity window, the timing was still way off. I tried importing them all at once and then one at a time. Same result.

I also tried exporting as audacity project. When I import it back into audacity it is still messed up.

You cannot export and import Audacity projects. If you save and reopen an Audacity project, track alignment should not change, even if you save a “compressed copy” of the project which exports the tracks as slightly lossy OGG files. The OGG files themselves will always start at zero, though.

We cannot see your computer. In what way is the alignment “messed up”, exactly? Use plenty of words. Explain it as you would to a little child.

If the imported audio starts at time zero when it should start some time after that, then for Export Multiple or Export Selection you will need to follow the steps you were given to add some silence at the start of the tracks that don’t start at zero.

Or for straight export (mixdown), you can simply add a track containing silence which is the length of the entire project.


I don’t know if any of this will help…

There is ALWAYS recording latency plus playback latency.
The buffers (and associated delays) are required for “smooth” audio in-and-out when you have a multitasking operating system. Big buffers (and long latency) are generally good things, and a bigger buffer can often avoid or prevent “glitches” in the audio.

Latency is constant (assuming you don’t change the hardware or software setup). Normally latency can be compensated for automatically, but since it’s constant throughout the recording it’s no big deal if you have to adjust for it manually.

Sometimes there is several minutes, or days or weeks, of “latency” between the time you record and play back, so a few extra milliseconds are no problem! :smiley:

Latency can be a BIG problem if you are monitoring yourself through the computer with headphones and the delay makes it difficult to perform. If your “live monitoring” path goes through the computer, this is when users try all kinds of “tricks” and adjustments to minimize latency. If the performer doesn’t need to monitor himself/herself through the computer, latency is simply NOT an issue to worry about. (Again, the latency from a backing track coming from the computer can be compensated for.)

Some effects (such as reverb) will sometimes introduce a delay and you may run across something called “Plug-in Delay Compensation”. That’s used to keep tracks in sync when applying different effects to different tracks.

MP3, and MP4/AAC are “lossy” compression formats…
The audio data is altered… When you compress there is a small amount of silence added to the beginning (and maybe the end). That’s a side-effect of these formats.

WAV is lossless. If you open/import a WAV file into Audacity and export to WAV (with the same settings), NOTHING WILL CHANGE and you’ll have an exact copy of the original. Even if you change the WAV settings or make some editing changes to the file, the timing will NOT change unless your edits involve timing, or cuts & splicing, etc., that can change the timing or length of the file.

Lossless compression (FLAC, etc.) results in the exact original data after decompression.


I’m trying to send this to a friend so he can add a part in Audacity.

There is another potential issue that can come-up when mixing-and-matching different hardware. The clocks (oscillators) in two different soundcards are always slightly different… Just like two clocks on the wall will always run at slightly different speeds.

You can end-up with a situation where the two tracks start-out in sync, but slowly drift apart. Sometimes “consumer” soundcards can be quite bad, causing the pitch to be off and/or causing the tracks to be out-of-sync by the end of a song. Sometimes you’ll see this problem when someone is recording with a good quality USB mic while monitoring a backing track on a consumer soundcard. The USB mic has it’s own clock, and when mixed the two tracks can be mis-matched.

Good audio interfaces usually have more precise clocks, and some regular soundards are just fine (or plenty good enough). Again like clocks on the wall, you shouldn’t get a noticable time difference during a 3-minute song… But some cheap soundcards are that horrible!

Pros use a “master clock” (and interfaces with master clock inputs). With everything running off the same clock, everything stays exactly synchronized.

Thanks for all the input.
for more clarification i’m on pc. We are recording live music, keyboard stereo, guitar, bass and vocal. My soundcard only has line in and mike input so we can only record two channels at a time into audacity. We are using a 12 channel mackie and we could try and mix it before it goes into audacity, but we would rather have it on separate tracks so we can overdub as needed. So we will put two tracks in usually keys and guitar. and will overdub the rest in audacity one track at a time. I followed the latency adjustment in the manual and found the latency to be 201 milliseconds. Under recording preferences I set it to that and it seems to work fine. Audacity adjusts for the delay and the tracks line up though the added tracks have little arrows at the beginning that are not on the first tracks. We then add bass and vocals the same way and it sounds fine. The problem is that I need to send them to the keyboard player who runs Mac and has audacity as well. When I try and export them and send them to him, when he loads it into his audacity program, the added tracks are way out of sync. Two or three seconds at least. The same thing happens when I export them from my Audacity in any format including wav, mp4, ogg, etc. When I bring them back into Audacity they are out of sync. They have not even left my computer. How can I send my friend the project we are working on so that he can add his part to it in Audacity. Evidently lots of folks are doing this successfully. I have been using export multiple which I think should work.

Gale, so what you are telling me is that if two people have Audacity in different locations they cannot work on a project together. If that’s the case, this program is not as great as I thought and is very limited. How then did they do that 4 part harmony that is referred to earlier in this post?

No that’s not what he is saying.
Working in different locations adds a bit of complexity to the task of multi-track recording, but it is perfectly possible.

The easiest way is to send the entire project to your collaborator rather than the individual tracks.
The downside of this method is that Audacity projects tend to be very large, but it is possible, either by using a file sharing service such as “dropbox”, or by copying the entire project onto a disk and posting it to them (“snail mail”).

Note that to send an Audacity project they will need both the AUP file and the _data folder.
A convenient way to do that is:

  • Before you start, create a folder on your computer.
  • Open Audacity, then “File > Save As” and save it into the folder that you have just made.
  • Do your recording and whatever editing that you want to do.
  • “File > Save”

You now have the entire project within the folder that you created in step 1.
Make a Zip file copy of that folder (you could use WinZip or similar)
Upload the Zip file to a file sharing service or burn it to a disk and send it by post.

When your collaborator receives the project, they will need to “unzip” (extract) the project from the Zip file onto their computer, then they can work on it.
To send it back to you they can use the same process.

Note that if you are working on different operating systems, you need to be careful about file naming. Windows in particular has a long list of naming conventions that you must stick to. The safest policy is to use only lower case “a to z”, “0 to 9” and underscore “_” in file names. Those characters are universally safe on all platforms.

If the above is not practical due to file size, please say so and we can describe alternative methods.

I was pointing out merely that your terminology was incorrect, which might confuse others reading this.

You said:

I also tried exporting as audacity project

but Audacity either “saves” projects in a format only Audacity can understand, or “exports” files in various common audio formats like WAV or MP3 that other audio programs can understand.

If Audacity saves a project, it does so as an AUP file and a _data folder. The _data folder contains many uncompressed audio files a few seconds long in an “AU” format that only Audacity understands.

Saving a compressed copy of a project is a “hybrid” - it saves an AUP file and _data folder but the _data folder does not contain uncompressed AU files. Instead, the _data folder contains compressed files in the common “OGG” format which Audacity exports there. If you don’t mind the project audio being very slightly lossy, saving a compressed copy of a project makes the project very much smaller than saving a standard project.

The only rational explanation that after Export Multiple, tracks are misaligned by a few seconds is that you have some tracks which begin at the start of the song and other tracks that start a few seconds later. To avoid Export Multiple ignoring the space at the start of the tracks that start later, you have to generate a little silence at the start of those tracks, as I described.

Or you can save a project instead which should preserve all track alignments.

It is also worth pointing out that you should File > Close the project before making the zip file of the AUP file and the _data folder.

If you just File > Save Project then make the zip, the _data folder will contain “extra” AU files that are there so you can undo and redo edits if you want to. However the AUP file will not list these extra files because they are not necessary for the currently saved state of the project. Therefore if you reopen a project that was zipped up while the project was open, Audacity will complain about these extra files, calling them “orphan block files”.

If that happens it should be OK to delete the orphans if everything is working as it should, but it is safest to tell Audacity to “continue without deleting” when it complains.


Oops. Good point, I forgot to list that step, but it can make a huge difference to the size of the Zip file as well as the “orphan file” warning that you mention.

For clarity I’ll give those steps again:

  • Before you start, create a folder on your computer.
  • Open Audacity, then “File > Save As” and save it into the folder that you have just made.
  • Do your recording and whatever editing that you want to do.
  • “File > Save”
    You now have the entire project within the folder that you created in step 1.
  • Close Audacity.
    This allows Audacity to clear up the “undo history”.
  • Make a Zip file copy of that folder (you could use WinZip or similar)

Thanks all, I think you’ve solved my problem I really appreciate the advise. I have one more question, is there any way we can get audacity tracks individually into Logic for eq mixing etc.? I’m guessing export muliple won’t work.

True, but only File > Close (leaving Audacity open) is necessary.


As we’ve said many times there is no known reason that export multiple should not preserve the alignment of each track if you generate silence at the start of each track that starts after time zero.

Isn’t that the problem, that some tracks start after time zero? Unfortunately, Audacity currently requires the extra step to generate silence at the start in order to preserve starting space.


Yes you can use Export Multiple (based on tracks), but in order to maintain synchronisation between tracks you need to ensure that all tracks start at time=0.0

I think Gale may have already given steps for that, but I can’t see them while I’m typing, so in case he hasn’t here’s a step-by-step way to ensure that all tracks start at time=0.0.

Writing in bold indicate keyboard shortcuts.

  • Home
    Cursor moves to the start of the project.
  • Shift + End
    Highlights to the end of the project.
  • Ctrl+Shift + K
    Extends the selection to all tracks.
  • Ctrl + T
    Trims to the selection.
    The above steps ensures that any “before zero” audio has been removed.
  • Home
    Returns the cursor to the start (time=0)
  • Generate menu > Silence. Generate 1 second of silence.
    It does not have to be 1 second, any convenient amount will do. This ensures that all tracks have some audio starting at time=0.0

Thanks, you guys are the best!

A slightly quicker “recipe” for deleting “behind zero” audio from all tracks:

  1. Ctrl+A
  2. Shift+Home
  3. Ctrl+T

Note that if any tracks start after time=0.0 you will still need to add silence to the start of all tracks by pressing Home, then generate some silence.

That was my problem, I had some tracks the started before zero.

Thanks, again