A project was created in an older version of audacity.
It contains click tracks and a few sample chords played on a piano, recorded in stereo.
I opened it in Audacity 2.0, running on Windows 7, 64 bit, and used “Export Multiple” to save the individual tracks.
The time from the click track to the chord presses is greater in the exported files.
Here is an example:
Audacity ® 2.0.0 (Unicode)
Header: AU (Sun/NeXT)
Encoding: 32 bit float
Split files based on Tracks
Numbering after File name prefix
overwrite existing files
Measurments from click onset to tones onset
Audacity project:
selection start at click onset 113393
Tones start at end of selection, 6076 samples
Results of export multiple
selection start at click onset 113393
tones start at end of selection, of length 14651
I would appreciate advice on how to get export multiple to generate files with the correct phase, or alternatively, advice on how to correct the exported files.
This screen shot shows:
At the top, notes in emacs.
At right, a measurement from onset of a click track to onset of a chord in another track, using the project file opened in Audacity 2.0.
At left, a measurement from onset from the same click to the onset of the same chord, using the exported files in another Audacity 2.0 session.
Procedure to generate left panel:
Export multiple from audacity project.
Open click track in a second audacity 2.0 session.
Import chord track into the second audacity session.
In each Audacity 2.0 session, the selection measures from click onset to chord onset.
The measurements in samples are visible at the bottom of the screen.
[Moderator note: Images cut down to fit forum page]
Additional info:
The last sample in the chord track measured in the original project file is sample 821,905
The last sample in the chord track, measured in the exported file, is sample 830,464
The last sample of the click track is sample 4,838,400 in both the project file and the exported file.
In the project file, the click track is a mono file, generated in Audacity. The click track is exported as a stereo file.
The number of samples in the first track of the project is 251,295
The number of samples in the exported version of the first track of the projec tis 260,096
So the number of additional samples in exported tracks is not a constant, and it is not proportional to the duration of the track.
I’ve edited the screen shots so that the fit better on the forum page. I may have got “before” and “after” the wrong way round.
When tracks are exported any “white space” at the beginning of the track is ignored.
If that is the cause of the issue you can get round it by adding a little silence at the beginning of any tracks that start after time zero.
OK, I’ve reversed them and added a comment to each.
The selection in both images start at 113,393 so it is the “chord” track that has moved or stretched by just under 0.2 seconds.
Check the track carefully. Is the discrepancy a constant 8575 samples or does it vary through the track?
Check at the beginning of the tracks - do you see any little arrows like this on any of the tracks?
What they signify is that the audio extends beyond (earlier) than time = 0.0.
Although the start of the audio is hidden behind the track start, it still exists and your exported tracks include that additional “pre-zero” audio.
The easiest solution is to trim off the pre-zero audio before exporting.
A quick way to do this:
Ctrl+A (select All)
shift+Home (adjust the start of the selection to the “start” t=0.0)
Ctrl+T (Trim)
You will notice that the arrows disappear when the pre-zero audio is trimmed off.
I’m trying this, but it somehow isn’t working. I’m using Windows 8, and Audacity 2.3
“The easiest solution is to trim off the pre-zero audio before exporting.
A quick way to do this:
Ctrl+A (select All)
shift+Home (adjust the start of the selection to the “start” t=0.0)
Ctrl+T (Trim)”
After Ctl+A;shift+Home;Ctl+T
Leftward arrows DO INDEED disappear.
Select all, followed by a time-shift to peak DOES INDEED show no data before the zero time point on any track.
HOWEVER -
Ctl+A (Select All) STILL begins the selection at a negative sample point.
Export multiple exports .wav files with the same number of samples as before the trim operation.
Saving as a new project and re-opening the project does not help either.
What do you mean by a “time-shift to peak”, with steps to perform that?
How are you finding this “negative sample point”, with steps to perform that?
We cannot see your project.
Perhaps you have clips lined up with the end of each track in which case the white space between the clips is rendered as silence and each exported track will have the same length.
Perhaps you did not really select all the tracks.
If you want to discuss this further I suggest you upload a project somewhere (AUP file and _data folder, copy the imported files in at File > Check Dependencies…) that demonstrates the issue.
