Is there a FOSS alternative to PluralEyes?

Software
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I’m looking for something that will allow me to sync the audio from my camera to audio recorded with an external device.

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I’ll have to try kdenlive, although at first sight I wasn’t able to find how to do the sync automatically.

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Right click on the reference clip, click “set audio reference”, right click on clip to be aligned, click “align to audio reference”. Worked >90% of the time for me.

You may have to wait a bit for the audio to be analysed, there’s a progress message in the status line.

2 Likes
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I’ve done this with ImageMagick. (Yes, honestly!) It is simple, automated, and fast.

The process for filming is: start cameras and digital recorder. Clap my hands where all devices can hear me. (A clapper-board would also work.)

In post, a script converts the audio recordings to images. Using image-processing techniques, it isolates the clap, and aligns the images using the clap. This gives the offsets to align all audio sources together. For convenience, the script adds silence to all tracks after the first so, using Audacity or similar, I can simply left-align the tracks.

EDIT to add: the images made from the audio are N pixels wide and one pixel high, where N is a large number. Pixel “brightness” is audio sample amplitude, mono not stereo. Theses are not waveform images. See Sound and vision.

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I can’t understand half of what you’re talking about.

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Do you mean me? If so, then I’m sorry.

I am more comfortable with images than I am with sound. For me, the key insight is that images and sound can be processed in identical ways. The terminology differs, but not the actual techniques.

However, if you are not familiar with image processing techniques, then my post won’t help you. Sorry.

1 Like
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@snibgo, yes you, but it’s entirely my fault.

Actually I have background in sound design and production (been a dj/producer for 10 years) and I’m also familiar with image/video processing techniques, however I am at a loss when it comes to the inner workings of these software, and coding/engineering jargon.

That said, I do appreciate your trying to help and I wanna reiterate that you need not apologize, it is I who is lacking.

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It is more about @snibgo’s approach to solving the problem. IM is his means for getting there.

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Oh man, I think you just blew my mind a little. It never occurred to me to approach this problem in this way and now I kinda want to run out and record some stuff just to play with it. :smiley:

1 Like
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I have used the clap to sync audio in Shotcut:

  1. Open the video
  2. Add the externally recorded audio to the timeline as another audio track
  3. Magnify the timeline to see the waveforms clearly. Align the clap in the external audio with the clap in the camera video (drag with mouse)
  4. Detach audio from the camera video and delete

It is a manual process but I found it quite easy.