Strange behaviour with audio overlay

I am currently trying to put an audio overlay (English audio) over a video in a different language.

I am trying to position the audio so that the English translation audio is more or less aligned with what is being said in the video. It doesn’t need to be perfect, simultaneous translation is always slightly delayed, but that is not my problem.

When I drag the audio file to the right position of the video, where it should start, it looks like everything worked well, the audio visualization is the same. But somehow the audio suddenly doesn’t start with the beginning, but somewhere in the way. I have the impression, that the audio track actually stays in the same position, only the “window” moves along. My guess is, this is a bug, but it might also be some error or misunderstanding on my side. I am using the latest release as available today, 21.10.31.

I am not sure if I expressed myself well. Trying to make clear what my problem is.

  1. So I put the video track into the timeline (zoom video conference), cut what is not needed at the beginning. There is a foreign language audio included.
  2. Then I add a audio file of the simultaneous translation of this interview.
  3. Of course, these two files are not perfectly aligned. The start of the video conference and the start of the audio recording made by the simultaneous translator are not starting 100% at the same time. No problem, I have solved this before, also in Shotcut.
  4. Now I am trying to drag the start of the audio track to the right position, where what is being said in both tracks (The original video/audio and the translation audio) match.

However, instead of moving the beginning of the audio track, it seems to just move the start of the audio track, as if I am not moving the audio file, but only move a “window” along.

Is this a bug, am I doing it wrong, how to solve my problem?

In English the “beginning” of something is the “start” of it. These 2 words are synonymous, so the sentence above does not make sense.

A screen shot of the whole Shotcut window may help to explain what is happening.

So a little update. I thought I am being intelligent and if the audio is causing problems, why not just moving the video to the right position and leave the audio where it is. But, what is weird, when I move the video, it just behaves as I would expect. It starts at a later point in the timeline.

The weird part: Despite me having only moved the video track and the additional auditrack still seeming to be at it’s right position (there is a short part that is almost silent at the beginning, so you can see it in the graph), the audio suddenly starts at a different position in the track… I am really confused. What was supposed to be a quick fix for doing language overlay on a video, is really confusing me.

Hi! Thank you for your quick answer and sorry for not being very clear. I am not a very experienced video editor, and I usually just do simple stuff (but looking into getting a bit more experience in the next couple of months to improve my skills).

So here a screenshot of what I have. There is the video file from zoom with the original audio embedded (which I will delete or silence later, once the translation is in place).

Then there is the audio with the English translation. So you see that the audio is basically starting a little later, with some “silence” (in the original file you can actually hear the original audio ever so slightly in the background). So this “gap” is basically the time lack in between the meeting starting and the simultaneous translator starting her translation. Normal stuff. But in the language overlay, I would like to get rid of this gap as much as possible, but just moving the audio file so that what is said in the video is more or less what is said in the translation.

The actual video has a lot more stuff at the beginning, but in an attempt to solve my problem (I can’t move the start of the audio to the right position of the video), I was cutting these parts out, so that the text in the video basically starts at the same point as the audio.

My problem is, that when I move the translation audio file, it visually moves to the correct position. But when I play it back, suddenly the English audio doesn’t start with the beginning as it should, because the audio track starts at this very position, but it starts somewhere in the middle of the actual audio.

However, somehow I have the impression, that it has to do with the play back. While the video plays back correctly, the additional audio file seems to continue where it had left off before, and doesn’t start where I put the marker.

Hmmm, so as my last suspicion was that the replay of the additional audio didn’t “reset” when I positioned the marker somewhere else on the timeline but rather played that audio track from where it had previously stopped, I did a restart of Shotcut and this seemed to have solved the problem.

I will observe this further, I still have to do this 2 more times with other videos and translation. I am not sure if this is a glitch in Shotcut, or if this was a temporary glitch on my computer. All in all, very weird and it drove me nuts, because I know that have done this before the same way I did it now.

If it happens again then it is unable to seek properly with your file. Not all formats and files can seek well under all conditions. Generally mp4a works well, but WAV is probably most reliable.

Let me go back to something you said earlier:

I wonder if you are referring to moving the left-hand edge of the clip rather than moving the whole clip. If you drag just the left hand edge towards the right, you are basically just trimming the start of the clip without actually moving it. In the clip below, note the double-arrow mouse cursor, indicating that I am dragging the edge; note also that the audio waveform is “covered up” as I move the edge, but the peaks and valleys stay in the same place:


Rather than pointing to the start of the clip and dragging it, point to somewhere in the “body” of the clip, and drag from there. In the example below, notice that the mouse cursor is a hand rather than the double-arrow - the hand indicates that I am going to move the whole clip. Note also that as I move the clip, the peaks and valleys in the waveform move - contrast that with the previous example above:


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That is what I thought first, but no. I was moving the whole track so that the starting and the end point would move (like in the second video).

The valleys and peaks of the sound wave would not disappear, they would still be the same, so you could still see the “silence” at the beginning of the track at the new position, but when you play it back it would give you the sound from somewhere in the middle of this track, rather than playing from the point where the marker line is put (and where the audio from the video was playing).

I closed Shotcut and the behaviour was gone. So for the second track everything worked “normal”. I assume it was just a temporary glitch.

That does sound like some sort of transient glitch. Glad it is working correctly now!

Yeah, I am glad too. Because Davinci Resolve was somehow too heavy for my computer and in my previous version it couldn’t handle the audio on Zoom videos (but Shotcut could). For the newest version I couldn’t even test it, because Resolve would just freeze on my.

Well, I have to admit, Shotcut did too at the beginning, but then I managed to open the video and the audio and edit without to many issues.

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