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TOPIC: Lightworks vs. ffmpeg same spot in same video have different timestamps

Lightworks vs. ffmpeg same spot in same video have different timestamps 9 months, 2 weeks ago #161113

  • kchoi01
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I want to cut out specific segments from a video using ffmpeg. I open the video in Lightworks and mark down the start and end times of the clips and use them as arguments to ffmpeg. The resulting clips' timings are way off. For example, a particular point in the video is 1:53 in Lightworks but I have to use a start time of 2:02 in ffmpeg to get the same spot.

Why do they have this discrepancy and what can I do to getting more accurate timings?
I notice that the frame rate is different. In Lightworks it is 30fps but ffmpeg shows 28.05 fps. Could this be the cause?

Re: Lightworks vs. ffmpeg same spot in same video have different timestamps 9 months, 2 weeks ago #161119

  • RWAV
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That'd do it every time. With a 28.05 fps rate it seems possibly your original clip has been made as a variable frame rate clip - to use it in LW it is best to transcode it into a fixed frame rate.

You might consider the following -

www.lwks.com/index.php?option=com_kunena&func=view&catid=23&id=66072&Itemid=81#66072

- for a description of basic requirements needed to give you more detailed advice.
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Re: Lightworks vs. ffmpeg same spot in same video have different timestamps 9 months, 2 weeks ago #161128

  • donkpow
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Why do they have this discrepancy...
Lightworks is assigning a standard frame rate to the video. Elapsed time will be based on that formula. ffmpeg will read the number of frames and other things then base the elapsed time on actual media.

Lightworks is designed as a professional tool and doesn't necessarily account for unusual stream parameters.
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Re: Lightworks vs. ffmpeg same spot in same video have different timestamps 9 months, 1 week ago #161142

  • kchoi01
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I checked with MediaInfo as suggested and saw that it has indeed a variable frame rate. Thanks for the quick replies!
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