Audacity Forum

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.

Koz

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.


Gale

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.

http://www.youtube.com/watch?v=PU8hXDim-1s

Koz

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.

kojac11 wrote: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.


Gale

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!

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.


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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.


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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?