shooting 50/25 cannot match audio

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Emilian Dechev

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shooting 50/25 cannot match audio

PostWed Aug 14, 2019 10:51 pm

So I shot a scene at 50fps slowmo for 25fps timeline - that is, the video playback is 50/25 so it plays slow in-camera.

Ok seems normal.

Then I realize, that I need to sync the audio. Of course, 50fps is exactly 2 times as much as 25fps, so one would think, that just speeding up the video twice (to 200% in Premiere) will match exactly with the audio that is 25fps anyway.

Wrong.

The audio always comes a bit shorter, like a few frames, or more than a second, for longer takes. Any thoughts?

P.S.
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John Paines

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Re: shooting 50/25 cannot match audio

PostWed Aug 14, 2019 11:02 pm

You won't get proportionally sync sound with off-speed frames rates, even when the off-speed rate is the same as the project rate. The manual makes this clear. Off-speed is for picture only.
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Emilian Dechev

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Re: shooting 50/25 cannot match audio

PostWed Aug 14, 2019 11:12 pm

I understand that, but I cant get the mathematics.

If the audio records at 25fps and the picture records at 50fps, why would not speeding up the picture by 200% get it in sync?

Sp the audio does not record at 25fps at off-speed rates. The difference in the timeline is so small, you can almost match it, but not quite perfect.
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javier forza

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Re: shooting 50/25 cannot match audio

PostThu Aug 15, 2019 12:53 am

Try 24 fps.
If this coincide exactly, the audio was recording at 24 and is a bug.
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CaptainHook

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Re: shooting 50/25 cannot match audio

PostThu Aug 15, 2019 4:48 am

Emilian Dechev wrote:I understand that, but I cant get the mathematics.

If the audio records at 25fps and the picture records at 50fps, why would not speeding up the picture by 200% get it in sync?

Sp the audio does not record at 25fps at off-speed rates. The difference in the timeline is so small, you can almost match it, but not quite perfect.

In off speed the video and audio are not running from the same clock, so they will drift. It may be close, but the longer the clip the more it will likely drift.
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