Export Multiple and FFmpeg

[chrzaszcz]

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.

[Gale Andrews]

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?


Gale

[chrzaszcz]

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.

[Gale Andrews]

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

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?

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.

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: http://forum.audacityteam.org/viewtopic ... 49&t=64936.


Gale

[chrzaszcz]

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 (191.25 KiB) Viewed 634 times

Screen Shot 2015-07-29 at 2.19.24 PM.png (136.08 KiB) Viewed 634 times

[steve]

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?

[chrzaszcz]

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.

[steve]

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/ex ... tiple.html)

[chrzaszcz]

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?

[steve]

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
Which version were you using where it worked ?