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Sorry, my question is not very well put out but I have trouble understanding my own problem.

I'm currently working on a music video project where I need to put green screened actors in a CGI scene. What I'm doing is using After Effects to color key the green screen out, then export each file with a transparent background before putting them in a 3D scene.

When I export the After Effects files, I choose to have them played at 24FPS. I then put them in a Blender file that is set at a 24FPS ratio. When I scroll the scene in Blender, the lip-syncing is on point and all the actors seem to be singing the song file imported in Blender. When the scene is done, i export the Blender file in order to put the scene in my Premiere Pro project. The Premiere project is also set at 24FPS.

The thing is, I export everything in a PNG sequence and when I place it in the Premiere timeline, its length doesn't match the song. It's the same song file that I've put in the Blender and Premiere projects. I did a test where I exported the Blender scene in a mp4 video file and, in this case, everything matches. There's a slight delay but nothing to be worry about.

So, to sum up the thing :

  • Everything from After Effects to Premiere is at 24FPS
  • Export in PNG sequence doesn't match
  • Export in MP4 does match (but looks awful)

How can there be two different 24FPS ? What am I missing ?

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Premiere and After Effects can default to import PNG files at different frames per second. Double check that they are definitely at 24 fps, and that your sequence in Premiere is set to 24 fps, and that your comp in After Effects is set to 24 fps. Was the original footage shot at 24 fps in the camera?

Another thought - where is the music originating from? Often video cameras record audio at 48kHz sample rate, but a lot of music is recorded at 44.1kHz sample rate. If you put a recording at 48kHz synced up with one at 44.1kHz that hasn't been sample rate converted, they won't play in sync.

Another thought: Blender defaults (or used to? can't remember) to play from frame zero, whereas Premiere/AE default to play from frame 1, so that may also cause you an issue.

In general, if your footage was shot at 24fps, and your whole pipeline is 24fps, your image sequence should be matching perfectly. If it isn't, it suggests to me that something is frame rate converting somewhere. If you in-camera settings were anything other than 24fps, I would work at your camera's frame rate throughout, otherwise you are more likely to have syncing issues. If you want to frame-rate convert to 24fps, do it after you have finished your visual effects.

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  • The footage is shot at 30fps but it shouldn't be a problem as after its conversion at 24fps in After Effects, it matches the 24fps of the Blender file, right ? I mean, how could Premiere possibly know that the footage was running originally at 30fps ? Regarding the music origin, it's an mp3 file that my project partner exported from Ableton or Audacity. It may not be up to certain kHz standards. And yes, Blender still defaults to play from frame zero but it's not the issue as it's a sliding problem that ends with a multiple frame delay.
    – the meedows
    Dec 12, 2022 at 8:17
  • If you've exported a new file from AE at 24fps, then you're right - Blender can't know the original file was 30. If you're converting from 30-24 in each application, then the way each app handles frame rate conversion may be different, and could cause some sync issues? I would work in 30fps throughout both projects., convert your mp3 to a 48kHz WAV, and see if you still get sync issues.
    – tomh
    Dec 13, 2022 at 9:23

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