Export Multiple and FFmpeg

I’ve twice tried using the Export Multiple feature to export multiple files with FFmpeg today, and the first time I did it, all of the files were successfully exported, but the first three had several minutes of blank audio at the end. The second time, I noticed that the same thing was happening for the first file I was trying to export (Audacity keeps exporting even after the progress bar fills up), so I stopped. Is anyone else having this problem? I’m running Audacity 2.1.1 on OS X 10.10.4 on an iMac from mid-2007.

Do I presume from your comment about the progress bar that you are exporting to M4A?

Where are you seeing or hearing the blank audio? Do the files look correct if you import them back into Audacity?

Do you have the same problem if you export multiple to WAV or AIFF?

What is the source of the audio before you export? A recording or imported files?


I just re-imported the first 4 files from my first attempt yesterday; the blank audio appears at the ends of the tracks (as I said before), which look normal apart from the said blank audio, and in one case exceeded 10 minutes in length, and after I edited the ones affected and copied and pasted the last three into the first one’s project, I tried exporting multiple to WAV, and the same thing happened to the first two files. I was exporting to M4A both times yesterday, and the ultimate source of all of these files was a recording.

What I was asking was - in what application you were seeing or hearing blank audio.

So you are saying that when you import the exported files back into Audacity that you see a section of flat line waveform?

So it is not a problem specific to FFmpeg.

Are you sure there are not silent parts in your recording or in your layout (for example, have you pasted so that there are silent parts in the project)?

If you need more help I suggest you show us a screenshot of the project you are trying to export from. To do that, View > Fit in Window, View > Fit Vertically, COMMAND + SHIFT + 4, then SPACE, then click the Audacity window, then attach the screenshot that is on the Desktop. Please see here for how to attach files: https://forum.audacityteam.org/t/how-to-attach-files-to-forum-posts/24026/1


A picture of the project with the re-imported files is attached. A picture of the first file I exported from that project with the export multiple feature is also attached; you’ll see that the flat line waveform at the end of the file is clearly not present in the original project. Since the blank audio appeared both there and in iTunes with files from my first attempt, the blank audio would almost certainly appear in any program you play the files in.
Screen Shot 2015-07-29 at 2.18.43 PM.png
Screen Shot 2015-07-29 at 2.19.24 PM.png

One possible explanation could be if there is a tiny fragment of audio at about 12:20 in the first track.
If you click on the first track somewhere near the beginning of the track and then press “Shift+K”, what happens?

If I do that, the track is highlighted from that point to the end at around 4:52. I did notice, however, that the blank audio ended precisely where the ‘Jailhouse Rock’ track began, so I did some experimenting, and I found that, at least when it is splitting tracks on the basis of labels created in a label track, the export multiple feature treats as part of the file being exported everything on one track between the label at the beginning of the file and the last break to audio on a different track that doesn’t have any audio before that on it. Thus, the export multiple feature finds nothing for considerable portions of such tracks and simply exports it as blank audio. I’m not a programmer, so I have no idea what to do from here.

Ah, I see what’s happening.

The way that one would normally use Export Multiple is either:

  • If you have a single track with multiple songs:
    Label each song and Export Multiple based on labels.
  • If you have multiple songs, each in their own track:
    Export Multiple based on tracks.

What you have is multiple songs, each in their own track AND each song labelled, and that is confusing Audacity.
I think it’s a bug that Audacity is confused in this way, but the simple solution is to use one of the above two methods rather than both.
(see: http://manual.audacityteam.org/o/man/export_multiple.html)

It is a bug; I’ve been using export multiple like that for a long time, and I never had this problem until now. Will it be fixed?

No doubt it can and will be fixed now that we know about it :wink:
Which version were you using where it worked ?

It was fine in 2.1.0; I don’t remember when I started using it like that.

I’m reviving this thread because although the issue of labels, multiple tracks, and export multiple appears in the ‘Known Issues’ section of the 2.1.2 release notes, it appears to have been fixed (by the way, I haven’t added my OS information because I’m running Audacity on two different computers that run on two different operating systems – you may want to add an option for that, and in this case, the OS is 10.10.5).

Probably not worth it for the few people that it affects. Just select the one that you use most, or like most, but if you’re posting about an issue on the other, mention it in your post.

Thanks but it is not fixed: http://bugzilla.audacityteam.org/show_bug.cgi?id=1199. The steps to reproduce still reproduce - I have just done so. Not necessarily all labels will be affected.


Exactly. I would need seven dropdowns to list all the OS’es I could run Audacity on.


You’re right, I’m sorry, I was using only two files on two tracks with two labels. By the way, would it e difficult to allow people to list more than one operating system at once? If it would be, perhaps you could just create a ‘Multiple’ option and leave it at that?

It is not difficult to add additional boxes for additional OS’es but it would be a pain for the overwhelming majority because if they did not select “None” in those additional boxes the registration form would be rejected. Without such a check there is no guarantee that the user with multiple OS’es has filled the form correctly.

“Multiple” would tell us less than if you filled in your main or most popular OS, which is what we recommend.

Also at this late stage we can’t add any extra items in the existing dropdown because it could change the already saved OS’es for some users.


Alright, and I see the instructions for the OS option say to select your main OS if you have more than one. If you ever do want to expand on it, I’m guessing the easiest thing to do would be to create a ‘Multiple’ option and have it trigger a text box that you would then manually enter your OSes into, but the current system seems to be generally alright the way it is.

So which is your “main” OS chrzaszcz ?

Yosemite, I’d have to say. I just added it.